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Highway andHighway and
TrafficTraffic
EngineeringEngineering
INTRODUCTIONINTRODUCTION
OverviewOverview
• This course aims at providing the
student an introduction to
Transportation Engineering. The
course is organized under five
modules. These are:
2
• Introduction to Transporation
Systems Engineering
• Transportation Planning
• Geometric Design
• Pavement Design
• Traffic Engineering
3
ObjectivesObjectives
• Introduction to Transportation
Systems Engineering
• Objective of this module is to give an overview of
the transportaion engineering.
• The focus will be to present a systems approach
where the interaction of humans and the vehicles
and their impact on the society and
transportation.
4
ObjectivesObjectives
• Transportation Planning plays an
important role in a region's strategy
to improve the performance of the
transportation system.
• Objective of this module is to
describe the basic characteristics of
transportation planning and of the
models used by transportation
planners.
5
ObjectivesObjectives
• Geometric Design of highways deals with the
dimensions and layout visible features such as,
alignment, sight distances and intersections.
• Objective of this module is to describe highway
design objectives, constraints and controlling
factors, also to describe the criteria, standards
and engineering procedures used to design
principal elements of the highway alignment, and
highway cross sections.
6
ObjectivesObjectives
• Pavement Design based on empirical and
mechanistic relations between materials,
geometry and performance.
• Objective of this module is to understand the
process of collecting information necessary for
successful design of flexible and rigid pavements,
including traffic data, material properties and
other environmental factors.
7
ObjectivesObjectives
• Traffic Engineering includes traffic signs,
markings, traffic signals, islands etc.
• Objective of this module is to understand
the basic parameter of traffic engineering
and the methods to estimate those
parameters.
• It examines ways to promote operational
efficiency and safety through the use of
traffic control devices.
8
9
S. # TOPICS
Lecture
Required
01 Transportation system: Introduction 1
02 Evolution of Transportation /Highway Development in Pakistan 1
03 Highway planning 1
04 Geometric design: Introduction/ Design controls 1
05 Design vehicle 1
06 Functional classification of roads and Design speed 1
07 Design Driver 1
08 Design Volume 1
09 Sight Distances 3
10
Cross section elements (with of travel lane, shoulders, medians
……)
2
MEHRAN UNIUVERSITY OF ENGINEERING AND TECHNOLOGY
RM-001/00QSP-004 Dec.01.2001
TENTATIVE TEACHING PLAN
DEPARTMENT/INSTITUTE/DIRECTORATE: CIVIL ENGINEERING
Name of Teacher: Prof. Dr. Abdul Sami Qureshi
Subject: Highway & Traffic Engineering Batch: 08CE- Year: Final Term: 1st
Term Starting Date: 03-01-2011 Term Suspension Date: 24-04-2011
10
09 Cross slopes 1
10 Horizontal Alignments: Introduction 1
11 Horizontal curves 2
12 Transition, curves 2
13 Super-elevation 2
14 Curve widening 1
15 Vertical Alignments: Introduction 1
16 Grades 1
17 Vertical curves 2
18 Pavement Design: Introduction 1
19 Early road construction methods 1
20 Design of flexible design 4
21. Design of rigid pavement 4
22. Maintenance of pavement 2
23. Traffic Engineering: Introduction 2
24. Volume studies 2
25. Highway safety 3
26. Highway capacity 3
27. Traffic control devices 1
28. Traffic signals 3
TOTAL 52
REFERENCESREFERENCES
1. HIGHWAY ENGINEERINGPAUL
H. WRIGHT/ KAREN K. DIXON
1. TRANSPORTATION ENGINEERING
C. JOTIN KHISTY-B. KENT LALL
1. HIGHWAY ENGINEERING
J. KHANNA
1. THE HAND BOOK OF HIGHWAY ENGINEERING
T. F. FWA
1. http://nptel.iitm.ac.in/
2. http://ocw.mit.edu/OcwWeb/web/home/home/in
dex.htm
3. HIGHWAY CAPACITY MANUAL
11
Overview ofOverview of
TransportationTransportation
EngineeringEngineering
What isWhat is
TRANSPORTATIOTRANSPORTATIO
N?N?
Transportation SystemTransportation System
Definition of Transportation Modes
• A transportation system is an
infrastructure that serves to move people
and goods efficiently.
• Efficient = safe, rapid, comfortable,
convenient, economical, environmentally
compatible.
Transportation SystemTransportation System
Major transportation subsystems
• Land transportation: highway, rail
• Air transportation: domestic,
international
• Water transportation: inland, coastal,
ocean
• Pipelines: oil, gas, other
TransportationTransportation
Movement of
persons and goods
over space
A B
MAJOR INTERACTING COMPONENTSMAJOR INTERACTING COMPONENTS
InfrastructureInfrastructure
Vehicle / ServiceVehicle / Service
Users /Users /
SubstanceSubstance
Users / ContentUsers / Content
• People → Passenger Transportation
• Goods → Freight Transportation
Shareoftotalpassengersor
tons-km
Distance
Passengers
Commuting
Shopping
Recreation
Business
Tourism
Migration
Waste disposal
Local distribution
Trade
Energy & Raw Materials
Freight
Source: Dr. Jean-Paul Rodrigue, Dept. of Economics & Geography, Hofstra University.
Users / substanceUsers / substance
Passengers Freight
Board, get off and transfer
without assistance
Must be loaded, unloaded
and transferred
Process information and
act on it without assistance
The information must be
processed through logistics
managers
Make choices between
means of transport often
irrationally
Logistics managers make
choices between means of
transport rationally
Source: Dr. Jean-Paul Rodrigue, Dept. of Economics & Geography, Hofstra University.
Vehicles / ServicesVehicles / Services
Vehicles / ServicesVehicles / Services
Vehicles / ServicesVehicles / Services
Vehicles / ServicesVehicles / Services
Vehicles / ServicesVehicles / Services
Vehicles / ServicesVehicles / Services
Vehicles / ServicesVehicles / Services
Vehicles / ServicesVehicles / Services
Vehicles / ServicesVehicles / Services
InfrastructureInfrastructure
InfrastructureInfrastructure
InfrastructureInfrastructure
ngram Publishing Royalty Free Photograph
InfrastructureInfrastructure
InfrastructureInfrastructure
InfrastructureInfrastructure
InfrastructureInfrastructure
Evolution of
Transportation /Highway
Development in Pakistan
36
Evolution of TransportationEvolution of Transportation
2000
Maritime Road Rail Air
180019001950
Docks
Locks
RailsOmnibus
Steam engine
Electric motor
Balloons
Dirigibles
Iron
hulls
Internal combustion engine
Metro
TramwayAutomobileLiners
Bicycles
PlanesTrucks
Buses
Electric
car
Hydrogen
car
Airfoils
Super
tankers
TGV
Maglev
Jet engine
Jet Plane
Container
ships
Helicopters
Bulk ships
Highways
Jumbo Jet
Evolution of TransportationEvolution of Transportation
1500-1840 Average speed of wagon and sail
ships: 16 km/hr
1850-1930 Average speed of trains: 100 km/hr.
Average speed of steamships: 25 km/hr
1950 Average speed of airplanes: 480-640 km/hr
1970 Average speed of jet planes: 800-1120 km/hr
1990 Numeric transmission: instantaneous
Source: Dr. Jean-Paul Rodrigue, Dept. of Economics & Geography, Hofstra University.
Evolution of TransportationEvolution of Transportation
100
500
1000
1800 1900 20001850 1950
50
250
750
Stage Coach
Rail
Automobile
HST
Propeller Plane
Jet Plane
Liner
Clipper Ship Containership
Road
Maritime
Rail
Air
Km
/hr
Evolution of TransportationEvolution of Transportation
• The TGV (French: Train à Grande Vitesse, meaning high-speed train) is
France's high-speed rail service
• A TGV service previously held the record for the fastest scheduled rail
journey with a start to stop average speed of 279.4 km/h (173.6 mph),[2][3]
which was surpassed by the Chinese CRH service Harmony express on the
Wuhan–Guangzhou High-Speed Railway in 2009.
• Maglev (magnetic levitation), is a system of transportation that suspends,
guides and propels vehicles, predominantly trains, using magnetic
levitation from a very large number of magnets for lift and propulsion.
• A hydrogen vehicle is an alternative fuel vehicle that uses hydrogen as
its onboard fuel for motive power
• Buses, trains, motorcycles,, ships, airplanes, submarines, and rockets can
already run on hydrogen, in various forms.The current land speed record
for a hydrogen-powered vehicle is 286.476 mph (461.038 km/h)
40
41
• Now a days Supertankers has a length overall of 380.0 metres
(1,246.7 ft) and a cargo capacity of 3,166,353 barrels
(503,409,900 l).
42
43
A jet aircraft is an aircraft propelled by jet engines. Jet aircraft
generally fly much faster than propeller-powered aircraft and at
higher altitudes – as high as 10,000 to 15,000 meters (about 33,000
to 49,000 ft).
44
A jumbo jet is a term used to describe a large aircraft, most
commonly the Boeing 747, after Jumbo, a famous elephant.
The 747-400, is among the fastest airliners in service with a high-
subsonic cruise speed of 570 mph, 920 km/h and can accommodate
more than 500 passengers.
What isWhat is
TRANSPORTATIOTRANSPORTATIO
N ENGINEERINGN ENGINEERING
??
Transportation EngineeringTransportation Engineering
• One of the specialty areas of civil
engineering
– Development of facilities (roads ,
railways, airports, Bus stops,..) for the
movement of goods and people
– Planning, design, operation and
maintenance
• Multidisciplinary study
• Transportation engineering:
• Science deals with efficient, safe, economical, comfortable
and speedy movement of goods and persons.
•
• Highway Engineering:
• It covers the construction of roads and providing the facilities
to road user and planning for safety or road vehicles etc.
•
• Railway Engineering:
• It deals with the lying of the railway track for movement of
heavy locomotives, wagons etc. it deals also with control of
movement with help of station yards.
•
47
• River and Harbour Engineering:
• Science deals with the development of docks and harbour
on sea or river shore for departure and arrival of ships and
other facilities for loading, unloading etc.
•
• Airport Engineering:
• Technique of development of runways, taxiways,
hanger, terminal building and control devices etc are dealt
in Airport engineering.
48
Transportation EngineeringTransportation Engineering
Transportation EngineeringTransportation Engineering
• An interesting / exciting area !
• Employers
– 50% government
– 40% consultants
– 5% research, teaching
– 5% other rail, trucking firms, etc.
Highway
Development in
Pakistan
51
Development of road:Development of road:
• Road extensively used before advent of railways
• Major roads work ignored but attention on feeder roads.
• End of 2nd
world war provided surplus military vehicles of
civilization.
• Boom to road construction and 1930 -- automobile age
•
• Highway related activities:
– motor vehicle registration
– highway expenditures
– road milage pass-Km, Tonn – Km.
– motor fuel consumption….
52
• Infrastructure and Economic
• Growth
• 􀂄 In the following slide a graph is presented that clarifies
the role of
• infrastructure in economic development (Source: Queiroz et
al, 1992
• – World Bank Working Paper).
• 􀂄 This slide shows a plot of the length of paved roads that
a country
• has versus its GNP
• 􀂄 98 countries were surveyed to plot this graph
• 􀂄 A clear correlation emerged between the Length of
paved roads
53
• (LPR) and the per-capita GNP (PGNP) according to the
following
• equation
• 􀂄 PGNP = 1.39 (LPR)
• 􀂄 This indicates that the more physical infrastructure a
country has (in
• this example we consider only transportation infrastructure,
but this
• relationship holds true for other types of infrastructure as
well), the
• greater the economic stability and vice versa.
54
55
The Infrastructure CrisisThe Infrastructure Crisis
• Despite the importance of infrastructure for economic and
social well-being, we are faced with several problems
• Infrastructure in developed countries is old, unreliable,
inefficient and in need of replacement.
• 􀂄 The USA is embarking on a major plan relating to
infrastructure spending
• 􀂄 In developing countries, infrastructure is often not
available
56
• 􀂄 Large portions of urban and rural populations in developing
countries haveinadequate access to water and sanitation
• 􀂄 Power supply is non-existent or unreliable and people are faced
with frequent power-cuts
• 􀂄 Quality of road infrastructure is often bad, leading to long
travel times and increased vehicle maintenance costs. Width of
roads is also often a constraining factor leading to traffic jams and
blocks.
• 􀂄 Several of these problems currently hold true for many areas in
India as well.
• 􀂄 This is therefore a golden opportunity for engineers with
technical as well as managerial and policy level knowledge of
these issues, since there is a huge demand for such people to
enter the workforce and solve the worlds infrastructure
inadequacies.
57
Why do we have so manyWhy do we have so many
problems with infrastructure?problems with infrastructure?
• 􀂄 This particular question and ways in which to solve it will
• the focus of this entire course. It is therefore impossible
• to answer this question right away. Before we conclude
• this session, we list out a few of the causes for the failure
• to provide adequate infrastructure
• 􀂄 Lack of funds
• 􀂄 Lack of implementation and management capabilities
• 􀂄 Corruption, bureaucracy and unfair competition
• 􀂄 Land acquisition issues involving dealing with displaced
people
• and special interest groups
• 􀂄 etc
58
INTRODUCTIONINTRODUCTION
PAKISTAN HIGHWAY SYSTEMPAKISTAN HIGHWAY SYSTEM
PAKISTAN
TRANSPORTATION
SYSTEM
 It contributes 11% in country's GDP & 5.46 % in employment
labor force
 It accounts for 90% passenger and 96% for freight traffic.
 Road transport is to be Considered the backbone of Pakistan
transport.
 It Carries about 80% of the Pakistan total transport.
60
Passenger Transportated in
Pakistan
2% 16%
82%
1 2 3
82% through Roadways
16% through Railways
2% with Airways
61
82
16
2
0
20
40
60
80
100
1 2 3
Cargo Transported in Pakistan
PAKISTAN HIGHWAYPAKISTAN HIGHWAY
SYSTEMSYSTEM
• 1947 – 49959Km
• 9759 Km (High type)
• 40200 Km (Low type... Earthen)
•
• 1985 – 118211 Km 5160 Km (High type) Growth Rate 2.29%→
• 1998 – 180000 Km (urban as well as rural)
• 2008-2009 -- 258,350 kms
• 23 National Highways, 7 motorways, 3 expressways & 3
Strategic roads.
• The length of high type road is 176,589kms and low type
road is 81,761kms.
• The total length of National Highways, Motorways,
expressways and strategic roads is 11857kms. Which is
4.6% of total length.
• Quite development but not satisfactory, when compared with
other countries area and population wise. 62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
Country Length (Km) per
100 Km2
Length (Km) per
1000 Km2
Japan
France
USA
Germany
India
Srilanka
274
174
64
168
50
38
>150
>120
--
>100
Pakistan 14 0.43
Pakistan Poorest Country
Even India has 3 to 4 times greater
Kilometerage
98
Lanes
1 Lane
2 Lane
2 – 3 Lane
3 – 4 Lane
> 4 Lane
61%
29%
5%
4%
Challenges For PakistanChallenges For Pakistan
• Increased traffic volume due to increased vehicle
ownership
• Dire deficiency of 346000Km to serve people
efficiently.
• To widen existing road network from single lane
to two
• If 3000Km constructed every year even then
require 100 years
• Big potential for opportunities for Highway
Engineers.
99
Existing Challenges for PakistanExisting Challenges for Pakistan
 Now- days over half the road is in poor condition and most of the
roads has been failed before their design life.
Failure is defined in terms of amount of cracking, rut depth, surface
roughness, skid resistance or other indicators
 The various factors which may cause the failure of pavement
are:
 Overloading
 Unsatisfactory Compaction
 Inadequate Drainage
 Frost action
 Quality of Material
 The material used does not compliance the specification.
 Laboratories do not follow the proper process in testing.
 Equipments are not properly working.
 End products are not according to specification and give less
results as compared to the required.
 This problem can be improved or partially solved by proper
“Quality assurance in testing of highway materials”.
HIGHWAYHIGHWAY
PLANINGPLANING
101
Highway Planning:Highway Planning:
• The making of plans and engineering investigation of the
project on a scientific basis rather than haphazard for
future Construction, maintenance and operation (Or for
new project or explained programs) is called Highway
Planning.
• A summary of major Data required for Highway Planning
are:
• An inventory of all rural roads (Width type, condition and
road bridges….)
• An estimate of volume and character of traffic
• Source of highway financing of the state and subdivision.
• An estimate of the number of the motor vehicles
ownership.
• Road life studies based on past records of construction and
reconstruction, from which service life can be estimated.
•
102
Object of Highway Planning:Object of Highway Planning:
 The proposed road should provide efficient, safe,
economical comfortable and speedy movements.
 It should have maximum utility within available
resources and other restraints.
 It should meet for anticipated future developments and
social needs.
 Highway planning should evolve financing system and
recommend changes in taxes and budget procedures.
 Highway Planning helps in phasing the road
development programs from financial consideration and
top most needy condition.
103
Principal of Highway Planning:Principal of Highway Planning:
• Equipped with traffic sign boards or
statutory provision for regulation
• Importance of road should be only
on traffic demand
• Road should from integral part of
network and form a part of
development schemes.
• There should be provision of
maintenance funds
104
Deficiencies of Highway planning:Deficiencies of Highway planning:
• No correlation to transport needs.
• No any base on systematic transport
survey
• No asses of base and horizon year traffic.
• No evaluation for qualitative
improvements in terms of geometric,
structural integrity, riding surface etc.
• No relation between transport plans with
other sector like agriculture, industry etc.
105
STUDIES/ DATA COLLECTIOINSTUDIES/ DATA COLLECTIOIN
REQUIRED FOR EFFICIENT PLANNINGREQUIRED FOR EFFICIENT PLANNING
• Field studies are conducted to collect the
data for assessment of road length
requirement for an area.
• Intelligent approach for efficient planning
• Helps in protecting any project from short
sightedness and shifting policies
• Detailed of surveys/studies are given
below for the development of a road
Project.
106
ECONOMIC STUDIESECONOMIC STUDIES
• Following details should be collected for economic studies
to determine the details of services given by the proposed
road to population & products of area which are useful in
estimating the economics involved
• Population and its distribution Trend of population growth
• Agriculture and industrial production and their listing in
classified groups and develop their future trends
• Per capita income
• Existing facilities like post office, School, Banks , etc
(Regarding communication, education and recreation to
estimate the Source of traffic)
• Country Highway mileage, its condition and distribution.
107
Financial Studies:Financial Studies:
• It is important to study various financial aspects like source
of income and their methods adopted to mobilize the fund
for project
• Source of income
• Estimating revenue from road transport
• Living standards
• Resources from local level, toll, Vehicle registration and
court fines etc.
108
Traffic and road use studies:Traffic and road use studies:
• Details of existing traffic, their volume and the pattern of
flow etc is necessary to plan for improvement in road
system or for construction of new road.
• Traffic Volume per day, AADT and peak hourly traffic
volume
• Origin and destination study.
• Mass transportation facilities
• Accidents, their cost analysis and causes
• Future trend and growth in traffic volume and goods traffic
• Growth of passenger trips and trend in the choice of mode
• Type of vehicle, gross weight, axle load, weight and length
or vehicle , commodity hauled etc are value able for road
design and regulation purpose
109
Engineering Studies:Engineering Studies:
• Detail of topography, Soil, Drainage and problems
related to construction and maintenance to be
investigated to chalk out plan. It needs
• Topographic survey
• Road location and alignment studies
• Soil surveys
• Location and classification of existing roads and
their types
• Road life studies, construction methods and
maintenance problems
• Special problems in drainage
110
PROJECT REPORT:PROJECT REPORT:
Project report should contain following details
• Introduction of project along with history and graphical
details
• Main requirements and factor of proposed alignment
• Details of alignment with respect to proposed width/
guage , gradients, length and levels of points
• Description about other proposed alternatives
• Details of proposed alignment with various dates and maps
• Specifications of the constructional standards
• Conclusion and recommendation of proposed project of new
railway line / High way.
111
Drawing to maps prepared along withDrawing to maps prepared along with
project report:project report:
• Overall map of that region to a scale 1 cm = 2Km.
• Index map of the area to a scale of 1 cm = 2.5 Km.
• detailed plan of proposed alignment with L section
• Contour plans and L section at bridge & culvert
• Plans of Bus stop to scale of 1 cm = 50 cm (Bus stop,
Rest , filling stations, Rest places)
• detailed drawing of all the bridges and buildings to a scale
of 1 cm = 1 m
• plan of level crossings to a scale 1 cm = 50 m
• details of important structures lying with 300 m on either
sides of the proposed rout
• Cross section at every important point should be prepared.
112
GeometricGeometric
DesignDesign
113
Geometric designGeometric design
• Criterion for the Selection of best
rout (Corridor Study).
• Design of visible features
114
Corridor StudyCorridor Study
The objective of the corridor study (highway
location study) is to establish highway's
centerline (baseline) and cross-sections in
relation to the terminal points and to the
topography of the area through which the
highway will pass.
The proposed highway route must be:
1. Economically justifiable,
2. Technically feasible, and
3. Environmentally acceptable.
116
Basic Principles for HighwayBasic Principles for Highway
LocationLocation
• There are an infinite number of ways to get from point A to
point B.
• selecting the best path between two points is called
Highway location
• Visible features of a road are Straight section; Transition
curve; Circular curve; Vertical curve; Cross-sections
• Visible features Roadway must be connected with each
other to design a road that provides for the easy flow of
traffic, while meeting design criteria and safety
standards.
Garber and Hoel, 2002
117
Factors Considered in the Selection ofFactors Considered in the Selection of
the best routthe best rout
• Topography
• Social and demographic characteristics
(including land use patterns)
• Terrain and soil conditions
Garber and Hoel, 2002
118
Factors Considered in the LocationFactors Considered in the Location
ProcessProcess
• Directness of route
• Serviceability of route to industrial and
population areas
• Crossing of other transportation facilities (roads,
railroads, rivers)
– Intersect other roads at right angle
Garber and Hoel, 2002
119
Factors Considered in the LocationFactors Considered in the Location
ProcessProcess
• Environmental
– Animal habitat
– Location of recreational, historic and
archeological sites
– Noise, air, and water pollution
Garber and Hoel, 2002
120
Factors Considered in the LocationFactors Considered in the Location
ProcessProcess
• Economic
– Construction
– Maintenance costs
– Road user costs
– Road user benefits (i.e. travel time)
– Adverse effects such as dislocation of
people or businesses
Garber and Hoel, 2002
ENGINEERINGENGINEERING
SURVEY FORSURVEY FOR
HIGHWAYHIGHWAY
LOCATIONLOCATION
121
ENGINEERING SURVEY FOR HIGHWAYENGINEERING SURVEY FOR HIGHWAY
LOCATIONLOCATION
• This survey is also called Route Survey and propose is to fix
the final road alignment
• and carried out in four stages.
• Map study
• Reconnaissance survey (Recci) Survey
• Preliminary survey
• Final location and detailed survey
122
123
124
300
A
300
A
400
350
475
B
A
350
340
330
375
100
B
20%
20
Costs
vs.
Desig
n
Level
Alt. 1
Alt. 1
Costs
vs.
Desig
n
Level
Alt. 2
Costs
vs.
Desig
n
Level
Alt. 2
Alt. 1
Costs
vs.
Desig
n
Level
129
Map Study:Map Study:
• It suggests the possible routes of the projected road out of
several likely alternative routes from available
• It gives the rough guidance about the route to be further
survey in the field
• The main features likes rivers hills valleys etc available on
maps helps in locating the alignment roughly avoiding
ponds and lakes.
• Give idea about approximate location of bridges, tunnels
etc.
• From map study it is also possible to drop a certain route
due to unavoidable obstructions.
• Topographic map having 15 or 30 meter contour intervals
could be used for this study.
130
::
Recci SurveyRecci Survey
• The main object of Recci survey is to examine in the field
the general characteristics of a stretch of land along the
proposed alternatives routes marked on the map.
• Following facts (not available in maps) are collected during
recci survey.
• e.g. Marshy land, ridge, hills, permanent structures and
other type of cross drainage structures, soil type along the
route, proximity of materials and labor etc.
• For that survey plans, land use plans, air photos, stream
and drainage maps etc. are used.
• As a result of recci survey a few alternative alignment (two
or three)may be chosen for further study.
• Recci survey is not required for minor relocation of an
existing road.
131
Preliminary Survey:Preliminary Survey:
• The preliminary survey decides the final route among two
or three routes after studying the advantages and
disadvantages.
• It is carried about with great accuracy and with critical
study
• Because the final route selection depends upon it and has
much effect on investment.
• Generally preliminary survey work is more or less an open
traverse survey of 60 to 300 meters wide belt along the
centre line of proposed (2 or 3) alternatives.
•
132
Preliminary SurveyPreliminary Survey
Preliminary Survey is done especially to collect below
information
• Geological information like soil, rocks, etc and their bearing
capacity
• Details of existing culverts, bridges, tunnels, irrigation
canal works etc.
• Position and details of level crossing proposed.
• Availability of construction material, labors, water along
proposed alignment.
• H.F.L. and L.W.L. of all river streams on paved alignment.
• Preliminary survey work is done mostly with Tachometer,
Level instrument, Prismatic compass and Plane table.
133
Preliminary SurveyPreliminary Survey
• All physical features e.g. building, posts of existing roads
and their radius of horizontal curves should be marked and
measured from transverse line.
• Grades at every 50m interval.
• Cross section at every 500m intervals.
• In order to have general idea to final centre line of
alternative alignment conforming to the design standards is
tried on plans.
• More suited alternatives from economic and other
consideration is finally chosen.
134
Location Survey:Location Survey:
• Here full detailed survey work will be done along most
economical route, determined by the preliminary survey.
• The final route marked on prepared plan is known paper
location, in which details of gradient, curves, contour,
direction crossing of streams etc are worked out.
• Then transfer of alignment from paper to ground is done in
the Final location Survey.
135
Final Location SurveyFinal Location Survey
• It consists in fixing up the centerline of the proposed
highway on the ground with the horizontal and vertical
controls. Final location involves two main operations.
• Sketching out of final centerline of the field.
• Beginning and end of circular and transition curves and all
other intermediate transit points (250m C/C) should be
fixed on center in case of new roads or by means of spikes
in the case of existing road.
• A single datum should be used for level works.
• Permanent bench marks should be established at every
250m, and at all drainage structure or on famous
reference point.
136
Final Location SurveyFinal Location Survey
– Detailed cross section at stations every 50m in plain
and at 25m in rolling terrain apart should be taken.
– In addition above other cross sections at the
beginning, middle and at end of spiral and of
circular curves should be taken up to the right-of-way
limits.
Detailed leveling.
– Longitudinal profile should also be taken for a stretch at
least 200m beyond then limit of the project.
• After protecting the points referencing Centre line the
construction survey is started.
137
138
Highway plan and profile
139
HOW IS HIGHWAYHOW IS HIGHWAY
LOCATION DETERMINED?LOCATION DETERMINED?
When Your Land Is Needed For Highway Use
Author: Stephen D. Holowach 7/23/99
http://www.119south.com/presentation/
• Establish the most direct and useable highway facility
at the least possible cost to the public.
• For undertakes intensive studies on several possible
routes
• Select the route that has the least possible
inconvenience or injury to the public and the private
landowner.
• Analyze the data concerning the economy, population
needs and traffic volume trends for the area under
study.
• Make the Aerial and ground surveys to consider factors
such as safety, drainage and soil types.
• Hold the public meetings to discuss the proposed
alternate locations.
140
RIGHT-OF-WAY?RIGHT-OF-WAY?
• Right-of-Way is the term used to describe the right
to pass over another’s land.
• When the government acquires land for Highway
Purposes it is actually obtaining “Right-of-Way” over
land on which a public road ultimately will be built.
• It is a Constitutional right of the government to
acquire land for public purposes
• The every Department of Transportation will execute
this right only when it will benefit the public.
141
What does a location study include?What does a location study include?
http://www.virginiadot.org/projects/studybris-http://www.virginiadot.org/projects/studybris-
coalfieldprocess.aspcoalfieldprocess.asp
Fully defining the project, or "scoping“
•This process is an opportunity to identify
issues and obtain comments from
agencies, jurisdictions and the public
early in the planning process.
•A "purpose and need" statement and the
goals and objectives of the Location Study
will be developed.
142
What does a location study include?What does a location study include?
(VDOT)(VDOT)
http://www.virginiadot.org/projects/studybris-http://www.virginiadot.org/projects/studybris-
coalfieldprocess.aspcoalfieldprocess.asp
Alternatives Identification
•Use technical data such as traffic counts and aerial
mapping and early environmental evaluations to develop
several possible road locations, or alternatives, within the
Study corridor.
•In this phase is to identify reasonable alternatives that
consider the input provided from communities, businesses
and individuals as well as regional concerns.
•Consider a number of new locations as well as upgrades
of existing roads.
•Look at the deficiencies of the existing transportation
network, including safety concerns and any planned
improvements along the study corridor.
143
http://www.virginiadot.org/projects/studybris-coalfielddefault.asp
144
145See also: http://www.interchange77-81.com/project_overview/default_more.asp
HIGHWAYHIGHWAY
ACTIVITIESACTIVITIES
147
4 ACTIVITIES4 ACTIVITIES
1. The existing physical
structure needs major
repair/replacement
(structure repair).
http://www.k5kj.net/jarrell.htm
148
4 ACTIVITIES4 ACTIVITIES
2. Existing or projected
future travel demands
exceed available
capacity, and access to
transportation and
mobility need to be
increased (capacity).
http://www.ens-
newswire.com/ens/sep2002/2002-09-19-
06.asp
149
4 ACTIVITIES4 ACTIVITIES
3. The route is experiencing
an inordinate number of
safety and accident
problems that can only
be resolved through
physical, geometric
changes (safety).
http://www.ems.ucla.edu/traffic/
ta10.htm
150
4 ACTIVITIES4 ACTIVITIES
4. Developmental pressures
along the route make a
reexamination of the
number, location, and
physical design of access
points necessary
(access).
GeometricGeometric
DesignDesign
151
Geometric DesignGeometric Design
• Geometric design is the aspect of
transportation engineering that deals with
• A) Selection of the best path between two
destinations.
• B) Deals with the design of visible features
of a road
• A good geometric design has to balance
balance operational efficiency, comfort,
safety, convenience, cost, environmental
impact, and aesthetics.
152
Geometric DesignGeometric Design
• Geometric design deals with the
design of visible features
• Visible features are
– Straight section
– Transition curve
– Circular curve
– Vertical curve
– Cross-sections
153
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
Design ControlsDesign Controls
170
Design ControlsDesign Controls
Factors which control the visible
features of the Highway
• Design vehicle
• Design speed
• Design volume
• Design driver
• Sight distance
• Highway classification……….
171
Design VehicleDesign Vehicle
DesignDesign VehicleVehicle
A design vehicle represents an individual
class in a conservative manner.
• passenger cars (compact, subcompact,
light delivery trucks),
• trucks (single-unit, tractor-semitrailer
combinations, trucks with full trailers),
• buses/recreational vehicles (single-
unit, articulated, school buses, motor
homes, passenger cars pulling trailers or
boats).
174
Design VehicleDesign Vehicle
• Design Vehicle – largest (slowest,
loudest?) vehicle likely to use a facility
with considerable frequency
• Three characteristics that affect almost
all aspects of highway design
– Physical
– Operating
– Environmental
175
Physical CharacteristicsPhysical Characteristics
• Type (GB defines 20 design vehicle types)
– Passenger Car P
– Buses B
– Trucks SU, WB
– RVs
– Farm tractor
• Size
– Length
– Height
– Weight
– Width
– Height of driver’s eye (car: 3.5’ – avg., truck: 7.6’ –
high side)
– Center of mass
176
Minimum Turning PathMinimum Turning Path
Passenger CarPassenger Car
Minimum turning path
is defined by the
outer trace of the
front overhang and
the path of the inner
rear wheel.
Minimum
Turning Path
Double-Trailer
Combination
Highway And traffic Engineering
Highway And traffic Engineering
Highway And traffic Engineering
CUT-AND-
COVER
TUNNEL RAMP UNDER
CONSTRUCTION
184
185
Dimensions of Design Vehicle TypesDimensions of Design Vehicle Types
186
Operating CharacteristicsOperating Characteristics
• Acceleration
• Deceleration and braking
• Power/weight ratios
• Headlights
• Friction (ball bank)
187
EnvironmentalEnvironmental
CharacteristicsCharacteristics
• Noise (noise meter)
• Exhaust
• Fuel Efficiency
• Dust (particulate and VOCs from tires
and brakes)
Vehicle PerformanceVehicle Performance
Characteristics
acceleration
deceleration
difficulties in maintaining steady speed
Use
intersections
freeway ramps
climbing or passing lanes, and
turnouts for buses
Vehicle PerformanceVehicle Performance
Exhibit 2-24
Vehicle Performance
Exhibit 2-25
Vehicles on GradesVehicles on Grades
• Passenger cars
– The upgrades up to 3% have a slight impact on
passenger cars.
– On steeper grades this effect becomes more
pronounced.
– No special consideration is needed.
• Trucks
– The effect of grades on truck speeds can be quite
strong (Exh. 3-53, 3-60).
– The truck with the mass/power ratio 120 kg/kW is
selected to represent heavy vehicles (conservative
assumption).
• Recreational vehicles
– Consideration of recreational vehicles on grades can
be justified for recreational roads with the low
percent of trucks (for example, to consider an
additional lane).
Effect of grade on truckEffect of grade on truck
performanceperformance
Crawling
speed
Effect of differential speedEffect of differential speed
on crash rateon crash rate
Critical Lengths of GradesCritical Lengths of Grades
195
Effect of grade on RVEffect of grade on RV
performanceperformance
Maximum Side FrictionMaximum Side Friction
Exhibit 3-
11
197
FrictionFriction
Design SpeedDesign Speed
Design VolumeDesign Volume
198
199
Design Speed andDesign Speed and
Design TrafficDesign Traffic
ConceptsConcepts
200
ObjectivesObjectives
 Get familiar with design speeds
for functional classes
 Describe traffic demand and
determine for roadway design
 Define ADT, AADT, DHV, D,
DDHV, K-Factor, and T
201
• Posted speed = speed limit
• Operating speed = free flow (spot
speed)
• Running speed = length of
highway section ÷ running time
• Design speed = selected speed
used to determine geometric
design features
Design speedDesign speed
• Design speed is the single most important factor
that affects the geometric design.
• It directly affects the sight distance, horizontal
curve, and the length of vertical curves.
• Since the speed of vehicles vary with driver,
terrain etc, a design speed is adopted for all the
geometric design.
• Design speed is defined as the highest continuous
speed at which individual vehicles can travel with
safety on the highway when weather conditions
are conducive.
202
Design speedDesign speed
• Design speed is different from the legal speed
limit which is the speed limit imposed to curb a
common tendency of drivers to travel beyond an
accepted safe speed.
• Design speed is also different from the desired
speed which is the maximum speed at which a
driver would travel when unconstrained by either
traffic or local geometry.
203
Design speedDesign speed
• Since there are wide variations in the speed adopted by
different drivers, and by different types of vehicles, design
speed should be selected such that it satisfy nearly all
drivers.
• At the same time, a higher design speed has cascading
effect in other geometric designs and thereby cost
escalation.
• Therefore, an 85th percentile design speed is normally
adopted.
• This speed is defined as that speed which is greater than
the speed of 85% of drivers. In some countries this is as
high as 95 to 98 percentile speed.
204
205
Design SpeedDesign Speed
 Design speed is defined by the AASHTO Green
Book as: ...the maximum safe speed that
can be maintained over a specified
section of highway when conditions are
so favorable that the design features of
the highway govern.
 Design Speed should: 1) “…be consistent
with the speed the driver is likely to expect.”
and 2) “. . .fit the travel desires and habits of
nearly all drivers.”
 Not posted speed and not operating speed
(but ALWAYS higher than both)
 See first part of:
http://www.fhwa.dot.gov/environment/flex/c
h04.htm (Chapter 4 from FHWA’s Flexibility in
Highway Design)
206
Design Speed ConsiderationsDesign Speed Considerations
• Functional classification of the highway
• Character of the terrain
• Density and character of adjacent land
uses
• Traffic volumes expected to use the
highway
• Economic and environmental
considerations
207
Design Speed in Green BookDesign Speed in Green Book
(suggested minimum design speed)(suggested minimum design speed)
Rural Local Roads
Source: A Policy on Geometric
Design of Highways and Streets
(The Green Book). Washington, DC.
American Association of State
Highway and Transportation
Officials, 2001 4th
Ed.
208
Design Speed in Green BookDesign Speed in Green Book
(suggested minimum design speed)(suggested minimum design speed)
Rural Collectors
Source: A Policy on Geometric
Design of Highways and Streets
(The Green Book). Washington, DC.
American Association of State
Highway and Transportation
Officials, 2001 4th
Ed.
209
Design Speed in Green BookDesign Speed in Green Book
(suggested minimum design speed)(suggested minimum design speed)
Rural Arterials
 60 – 120 kph (40-75 mph)
 Depends on …
Terrain
Driver expectancy
Alignment (reconstruction)
210
Design Speed in Green BookDesign Speed in Green Book
(suggested minimum design speed)(suggested minimum design speed)
Urban
• Locals 20-30 mph
• Collectors 30 mph+
• Arterials 30-60 mph
211
Values represent the
minimum acceptable
design speeds for the
various conditions of
terrain and traffic
volumes associated
with new or
reconstructed
highway facilities
212
InternationalInternational
213
Design TrafficDesign Traffic
214
Traffic DefinitionsTraffic Definitions
• Volume:
– number of vehicles, pedestrians, etc.
passing a point during a specific
period of time
– for vehicles, usually expressed as
veh/hour (vph) or veh/hour/lane
(vphpl)
215
• Demand:
– number of vehicles, pedestrians, etc. that desire to
travel between locations during a specific period
– Frequently higher than volume during certain peak
times
– Trips are diverted or not made when there are
constraints in the system
– difficult to measure actual demand because capacity
constrains the demand
• Capacity:
– maximum number of vehicles that can pass a point
during a specific period
– A characteristic of the roadway or facility
216
Characteristics of Traffic FlowCharacteristics of Traffic Flow
• Highly variable
– Time of day
– Day of week
– Season
– Road characteristics
– Direction
217
0
1000
2000
3000
4000
5000
6000
7000
12:30
A
M1:30
A
M2:30
A
M3:30
A
M4:30
A
M5:30
A
M6:30
A
M7:30
A
M8:30
A
M9:30
A
M10:30
A
M11:30
A
M12:30
PM1:30
PM2:30
PM3:30
PM4:30
PM5:30
PM6:30
PM7:30
PM8:30
PM9:30
PM10:30
PM11:30
PM12:30
A
M
Time of Day
Flowinvehiclesperhour
Highway Capacity
Highly Congested
Traffic Typically Peaks twice per dayTraffic Typically Peaks twice per day
Source: www.ecn.purdue.edu/~darcy
218
Volume StudiesVolume Studies
• AADT: Annual average daily traffic
(counted for 365 days)
• ADT: average daily traffic (counted
for > 1 day and < 365)
• PHV: peak hour volume
• Classification counts: fleet mix
219
Estimating AADTEstimating AADT
• Annual Average Daily Traffic
• Use count station information
• Extrapolate to non-count locations
• Used to adjust ADT for
– Seasons
– Daily variation
220
AADT Data Helps to:AADT Data Helps to:
• Estimate highway revenues
• Establish overall volume trends
• Establish annual accident rates
• Analyze benefits of road
improvements
221
Counting ProgramCounting Program
• To satisfy the traffic volume data
needs for all roads under a particular
jurisdiction, we establish a Counting
Program
A systematic pattern of counting
at different times and locations
222
Traffic Counts MapsTraffic Counts Maps
http://www.iowadotmaps.com/msp/traffic/index.html
223
Traffic Counts MapsTraffic Counts Maps
224
Design VolumeDesign Volume
• Usually hourly volume
• Which hour?
– Average hourly volume – inadequate design
– Maximum peak hour – not economical
– Hourly volume used for design should not be
exceeded very often or by very much
– Usually use 30th
highest hourly volume of the
year
– On rural roads 30 HHV is ~ 15% of ADT
– Tends to be constant year to year
225
Traffic DemandTraffic Demand
 Design Hourly Volume (DHV) – future
hourly volume (both directions) used
for design - typically 30th
HHV (highest
hourly volume) in the design year
 Why 30th
HHV?
 Breakpoint of 2-28
 Compromise: too high is wasteful, too
low poor operation
 Approximately median weekly peak hour
volume (top highest week peak hours)
(30th
HHV exceed 29 times in year)
226
Traffic Demand (cont.)Traffic Demand (cont.)
3. Exhibit 2-28 relationship between HHV and percent of
ADT in peak hour (referred to as K-factor)
Source: A Policy on
Geometric Design of
Highways and Streets
(The Green Book).
Washington, DC.
American Association of
State Highway and
Transportation Officials,
2001 4th
Ed.
227
Design Hourly VolumeDesign Hourly Volume
DHV is a representation of peak hour traffic,
usually for the future, or horizon year
K-factor represents proportion of AADT that
occurs in the 30th
HHV
K-factor = __DHV x 100
AADT
K = 8 to 12% urban, 12 to 18% rural
228
Design Hourly Volume (Example)Design Hourly Volume (Example)
If AADT is 3500 vpd and the 30th
highest hourly volume for the year is
420 vph what is the K-factor for that
facility?
K-factor = __DHV x 100
AADT
K-factor = __420 x 100 = 12
3500
229
Question: What’s the impact of choosingQuestion: What’s the impact of choosing
different K factor for design?different K factor for design?
If AADT is 3500 vpd, how will the design volume differ for K-
factor = 8% vs. 12%?
DHV = K-factor x AADT
100
DHVk=8% = 8 x 3500 = 280 vph
100
DHVk=12% = 12 x 3500 = 420 vph (diff of 140
100 veh)
230
Traffic Demand (cont.)Traffic Demand (cont.)
• D = directional distribution = one
way volume in peak direction
(expressed as a percentage of two-
way traffic) Rural 55 to 80%
• Can also adjust for how traffic is
distributed between lanes (e.g., 3
lanes, highest/outside lane may be
40% of total directional flow)
231
Directional DistributionDirectional Distribution (example)(example)
If traffic is directionally split 60/40, what is directional distribution of
traffic for previous example (Design hourly volume = 420 veh/hr)?
Directional Design Hourly Volume (DDHV) =
0.6 x 420 = 252 veh/hr
Notice we use 0.6 not 0.4!!
232
Traffic Demand (cont.)Traffic Demand (cont.)
• T = percentage of heavy vehicles during
design hour (Iowa interstate 35% plus)
• Affects capacity, ability to pass on two-
lane rural roads, etc.
• Larger, occupy more space
• Should determine % during design hour
(truck patterns may not be same as
passenger vehicles)
233
PHF = peak-hour volume
4(peak 15-min volume)
Flow is not uniform throughout an hour
HCM considers operating conditions
during most congested 15-minute
period of the hour to determine service
level for the hour as a whole
Peak Hour Factor (PHF)Peak Hour Factor (PHF)
234
Peak Hour FactorPeak Hour Factor
235
DHV = Peak-Hour Volume
PHF
Example
Peak hour volume from previous = 375
vph
PHF = 0.625
DHV = 375 = 600 vph
0.625
Note: the traffic you design for is the
busiest 15 minutes during the peak
hour … another way to think of it is 150
vehicles per 15 minutes = 600 vehicles
per 60 minutes
236
Design DriverDesign Driver
LECTURE 6LECTURE 6
237
238
Design DriverDesign Driver
CharacteristicsCharacteristics
• Design Driver: driver most expected
to use facility (familiar or
unfamiliar?)
– Accommodated in design, signing, etc.
239
Design Driver CharacteristicsDesign Driver Characteristics
Cont.Cont.
• Physical characteristics
• Processing ability
• Tolerable
Accelerations/Decelerations
– Longitudinal (along roadway )
– Lateral (around curves)
– Vertical (comfort)
240
Design Driver CharacteristicsDesign Driver Characteristics
Cont.Cont.
• Others?: age, gender, physical
condition (alcohol, etc.), mental
capabilities, skill (self perception – are
you in the top ½ of driver skill?)
• Two others related to design:
perception-reaction time and
expectancy
241
Design DriverDesign Driver
• Wide range of system users
• What range of drivers use the
system?
– Ages: 16 year old to 80 year old
– Different mental and physical states
– Physical (sight, hearing, etc)
– experience
• Design Driver: driver most expected
to use facility
242
0
2
4
6
8
10
12
PercentofDrivingPopulation
<20
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65-69
70-74
75-79
80-84
>84
Age Groups
243
Visual AcuityVisual Acuity
244
Visual ReceptionVisual Reception
• Visual Acuity: Ability to see fine details
• Static (stationary objects):
–Depends on brightness
–Increases with increasing brightness
up to ~ 3 candles (cd/sq ft) --
remains constant after that
–Contrast
–Time (0.5 to 1.0 second)
• Dynamic (ability to detect moving
objects)
–Clear vision within a conical angle 3 to
5º
–Fairly clear within 10 to 12º
–Key criteria in determining
placement of traffic signs
245
Visual ReceptionVisual Reception
• Peripheral Vision: Ability to see objects
beyond the cone of clearest vision (160
degrees)
– Age dependent
– Objects seen but details and color are not
clear
246
Visual ReceptionVisual Reception
• Color Vision: Ability to differentiate
one color from another
– Lack of ability = color blindness
– Combinations to which the eye is the
most sensitive
• Black and white
• Black and yellow
y in determining traffic signs colors
247
Visual ReceptionVisual Reception
• Depth perception
– Ability to estimate speed and distance
•Passing on two-lane roads
•Signs are standardized to aid in
perceiving distance
248
Hearing
Hearing perception
– Ability to detect warning sounds
– Sirens, horns
249
Perception/ReactionPerception/Reaction
TimeTime
250
Perception-Reaction ProcessPerception-Reaction Process
• Perception
• Identification
• Emotion
• Reaction (volition)
PIEV
Used for Signal Design and Braking Distance
251
Perception-Reaction ProcessPerception-Reaction Process
• Perception
– Sees or hears situation (sees deer)
• Identification
– Identify situation (realizes deer is in
road)
• Emotion
– Decides on course of action (swerve,
stop, change lanes, etc)
• Reaction (volition)
– Acts (time to start events in motion
but not actually do action)
• Foot begins to hit brake, not actual
deceleration
252
Typical Perception-Reaction
time range is:
0.5 to 7 seconds
Affected by a number of
factors.
What are they?
253
Perception-Reaction TimePerception-Reaction Time
FactorsFactors
• Environment:
• Urban vs. Rural
• Night vs. Day
• Wet vs. Dry
• Age
• Physical Condition:
• Fatigue
• Drugs/Alcohol
• Distractions
254
Perception-Reaction TimePerception-Reaction Time
FactorsFactors
• medical condition
• visual acuity
• ability to see (lighting conditions, presence
of fog, snow, etc)
• complexity of situation (more complex =
more time)
• complexity of necessary response
• expected versus unexpected situation
(traffic light turning red vs. dog darting
into road)
255
256
Perception Reaction Time (PRT)Perception Reaction Time (PRT)
• Time from Perception to Initial
Reaction to Stimulus (Example)
257
AgeAge
• Older drivers
– May perceive
something as
a hazard but
not act quickly
enough
– More difficulty
seeing,
hearing,
reacting
– Drive slower
258
AgeAge
• Younger drivers
– May be able to act quickly but not have
experience to recognize things as a hazard
or be able to decide what to do
– Drive faster
– Are unfamiliar with driving experience
– Are less apt to drive safely after a few
drinks
– Are easily distracted by conversation and
others inside the vehicle
– May be more likely to operate faulty
equipment
– Poorly developed risk perception
– Feel invincible, the "Superman Syndrome”
Human Factors - Perception and Reaction
by Joseph E. Badger. jebadger@harristechnical.com
259
AlcoholAlcohol
• Affects each person differently
• Slows reaction time
• Increases risk taking
• Dulls judgment
• Slows decision-making
• Presents peripheral vision
difficulties
Human Factors - Perception and Reaction
by Joseph E. Badger. jebadger@harristechnical.com
260
ExperienceExperience
• Even NASCAR drivers practice
Familiarity
Faster on familiar
Unfamiliar more distracted
– Rental car on unfamiliar road at 10 pm when it starts
to rain (What is the driver doing?)
261
WeatherWeather
• Fog
• Rain
• Ice
• Snow
• affects ability to see (snow, fog)
• changes ability to stop (ice, snow,
wet)
262
UnderstandingUnderstanding
Flashing
DON’T
WALK
263
UnderstandingUnderstanding
Count down
signal
264
265
UnderstandingUnderstanding
• Most people do not reduce speed
in a work zone until they actually
see activity
• Only 78% of drivers in a study
understood what “Lane Ends”
mean
• Many people, especially older
drivers, don’t understand meaning
of left turn displays
Human Factors - Perception and Reaction
by Joseph E. Badger. jebadger@harristechnical.com
266
FatigueFatigue
• Increases perception/reaction
time
• Study by American
Automobile Association found
that in 221 truck accidents
only 18.4% of the drivers had
been driving less than nine
hours.
• 41% of truck accidents
Human Factors - Perception and Reaction
by Joseph E. Badger. jebadger@harristechnical.com
267
Dp
= 1.47(V)(t)
where:
Dp
= Distance traveled during PIEV
process (feet)
V = velocity (mph)
t = perception-reaction time = 2.5s
268
How much longer does it take an impaired driver to
perceive/react than an unimpaired one at 65 mph?
Unimpaired has P/R time of 2.5 seconds
Dp
= 1.47(V)(t) =
1.47(65 mph)(2.5 sec.) ~ 240 feet
Impaired Driver has P/R time of 4 seconds
Dp
= 1.47(65 mph)(4 sec) ~ 380 feet
Difference is 380 – 240 = 140 feet
Difference is safety and economic problem!
Example
269
Perception/ReactionPerception/Reaction
ApplicationsApplications
• Stopping sight distance
• Passing sight distance
• Placement of signs/traffic control
devices
• Design of horizontal/vertical curves
270
DriverDriver
ExpectancyExpectancy
271
Driver ExpectancyDriver Expectancy
• Expectancy (def) – an inclination based
on previous experience to respond in a
set manner to a roadway, traffic, or
information situation
• Types
– A Priori – long-term (based on
collective past experience) PRT =
0.6s avg., some 2.0s
– Ad Hoc – short-term (based on site-
specific practices/situations
encountered during a particular trip
on a particular roadway, PRT = 1.0s
avg., some 2.7s
272
Driver ExpectancyDriver Expectancy
• Driver Expectancies (what do we
expect as drivers?)
– Specific colors (red = stop)
– Driver ahead not to decelerate rapidly
– Slower drivers in left lane
– Work zone signs = people working
– Lane size
– Etc.
273
Selection ofSelection of
Design DriverDesign Driver
274
Design criteria must
be based on the
capabilities and
limitations of most
drivers and
pedestrians
275
The 85th
percentile is generally
used to select Design Criteria
The 95th
percentile or higher is
used where the consequences
of failure are severe
AASHTO recommends 2.6
seconds for stopping sight
distance (90th
)
276
RRole of Transportationole of Transportation
EngineerEngineer
• allow proper sight
distance in design,
sign placement
• avoid hitting driver
with too much info
at once
– one sign at a time
• clarity (sign size,
color, reflectivity)
277
Driver Activities in Selection ofDriver Activities in Selection of
PathPath
• Control (overt actions)
– Road Edge
– Avoid a Car
• Guidance (decisions)
– Lane Placement
– Car Following
– Passing
278
Driver Activities in Selection ofDriver Activities in Selection of
Path Cont.Path Cont.
• Navigation Level (planning)
– Maps
– Observe a directional sign
Sight DistancesSight Distances
279
280
Important Sight DistancesImportant Sight Distances
1. Stopping
2. Decision
3. Passing
4. Intersection
5. Crossing RR
FIRST AND THIRD WILL BE DISCUSSED
HERE
281
Sight Distance in DesignSight Distance in Design
• For safety, should provide sight distance
of sufficient length so that drivers can
control the operation of their vehicles to
avoid striking an unexpected object in the
traveled way - STOPPING SIGHT
DISTANCE (SSD)
• Certain 2-lane roads should have sufficient
sight distance to enable drivers to occupy
the opposing traffic lane for passing other
vehicles without risk of crash - PASSING
SIGHT DISTANCE (PSD)
282
Green Book (AASHTO)Green Book (AASHTO)
Policy QuestionPolicy Question
• Sight distance assumes drivers are
traveling at:
– A. The posted speed limit
– B. 10 mph above the speed limit
– C. The 85% percentile spot speed of
the facility
– D. The design speed of the facility
283
Design Policy - ResponseDesign Policy - Response
• Sight distance assumes drivers are
traveling at:
– A. The posted speed limit
– B. 10 mph above the speed limit
– C. The 85% percentile spot speed of
the facility
– D. The design speed of the facility
284
GB Question with responseGB Question with response
• Stopping sight distance is composed
of two distances, what are they?
– Distance traveled during
perception/reaction time
– Distance required to physically brake
vehicle
285
Studies onStudies on
Perception/Reaction TimePerception/Reaction Time
• 321 drivers (Johansson and Ruma):
drivers expected to use brakes
– Median: 0.66 sec
– 90th
percentile: >= 1.5 sec
• Unexpected, response time increased by ~
1 sec
• Some drivers took over 3.5 seconds to
respond even under simple test condition
286
GB QuestionGB Question
• AASHTO GB recommends 2.5
seconds, this is adequate for
conditions that are more complex
than the simple conditions used in
laboratory and road tests.
287
Sight distanceSight distance
Distance a driver can see ahead at
any specific time Must allow
sufficient distance for a driver to
perceive/react and stop, swerve etc
when necessary
288
Stopping Sight DistanceStopping Sight Distance
(SSD)(SSD)
 Required for every point
along alignment
(horizontal and vertical) –
Design for it, or sign for
lower, safe speed
 Available SSD =
f(roadway alignment,
objects off the alignment,
object on road height
 SSD = PRT + BD (with
final velocity V2
= 0)
289
Criteria for Sight DistanceCriteria for Sight Distance
• Driver eye height: for passenger
vehicle’s = 3.5 ft above surface
• Height of object in roadway = 2 feet
(SSD)
• Height of opposing vehicle = 3.5 feet
(PSD)
290
Deceleration rate: AASHTO: 11.2 ft/s2
Deceleration is within capability of drivers
to stay within their lane and control the
vehicle when braking on wet surfaces and
is comfortable for most drivers
• AASHTO represents friction as a/g
which is a function of the roadway, tires,
etc
• Can use when deceleration is known
(usually not)
291
BD = V2
30[ (a) ± G]
(g)
Where:
BD = braking distance (ft)
V = speed (mph) (can also be “u”)
a = deceleration rate (ft/s2
)
G = grade (decimal)
g = acceleration due to gravity =32.2 ft/s2
292
Braking DistanceBraking Distance
Assumes a rate of deceleration, driver may brake harder
a = 11.2 ft/sec2
normal
a = 14.8 ft/sec2
emergency, use tables from AASHTO
Friction is a function of pavement condition (wet, icy), tire,
and roadway surface
Depends on weight, but some assumptions are made to
arrive at a standard equation
293
SSD EquationSSD Equation
SSD = 1.47ut + _____u2
_____
30({a/g} ± G)
SSD in feet
u speed in mph (may also see “v”)
t perception/reaction time (in seconds)
a assumed deceleration rate (ft/sec2
)
g gravitational force (32.2 ft /sec2
)
G gradient in ft/ft
294
SSD ExampleSSD Example
Use basic assumptions to determine SSD at 60 mph on
a) 0% grade, b) 3% grade
SSD = 1.47u(2.5 sec) + ________u2
________
30({11.2/32.2} + 0.00)
SSD = 220.5 + 345.5 = 556 ft
(compare to table 3-1 in GB – See next slide)
On a +3% grade, SSD = 220 +318 = 538 ft
295
Stopping
(emergency) –
SSD (Table 3-1)
Source: A Policy on Geometric Design of
Highways and Streets (The Green Book).
Washington, DC. American Association of
State Highway and Transportation Officials,
2001 4th
Ed.
296
SSD ExampleSSD Example
Given: Available Sight distance = 430’ on a +3% grade
Find maximum speed if perception reaction time is assumed to be 2.5
seconds
430 feet = 1.47u(2.5 sec) + ________u2
________
30({11.2/32.2} + 0.03)
430 feet = 3.68u + ________u2
________
30(0.378)
Solving for u, u = 52.0 mph (Set speed at 50
mph)
Discuss: Would this be an acceptable condition if
the road is generally posted for 60 mph?
297
Stopping Sight DistanceStopping Sight Distance
ExampleExample
Consider analysis when vehicle skids
across different surfaces (a/g is not
equal to 0.35)
Or final velocity is not zero at the end of
the skid, as evidenced because the
vehicle sustains crushing damage until
the vehicle is stopped.
298
Stopping Sight DistanceStopping Sight Distance
where:
terms are as before, except
vo = original velocity
vf = final velocity at impact
With assumed acceleration, using friction
S = PRD + Db
= 1.47vot + vo2
- vf2
30(f ± G)
299
Stopping Sight DistanceStopping Sight Distance
ExampleExample
Accident Reconstruction:
Average Skid Mark = 47 feet
Crush damage indicates 20 to 30 mph speed at impact
f = 0.65 (how do they know this?), level roadway, and 40 mph posted
speed.
Was vehicle speeding?
47 feet skid represents what? BD?
If final speed is 30 mph …
BD = 47 = (Vi
2
– 302
)/30(0.65 + 0)
Vi
= 42.6 mph
If final speed is 20 mph (Vi
= 36.3 mph)
What if pavement changes to gravel after 47 feet and car slides
another 30 feet (f = 0.7)? What is initial speed?
300
Typical values for frictionTypical values for friction
Values of friction vary widely with road
surface type, age, condition. Examples:
Surface type f (or a/g)
Concrete pavement -dry 0.60 to .75
Concrete pavement – wet 0.45 to .65
Asphalt pavement 0.55 to .70
Gravel 0.40 to .70
Ice 0.05 to .20
Snow 0.30 to .60
Source: Lynn Fricke, Northwestern Univ.
301
Decision Sight DistanceDecision Sight Distance
• SSD are sufficient to allow reasonably
competent and alert drivers to come to a
hurried stop under ordinary circumstances
• May be inadequate when drivers must
make complex or instantaneous decisions,
when information is difficult to perceive or
when unexpected or unusual maneuvers
are required
• Equations in book, use tables
302
Decision Sight DistanceDecision Sight Distance
• When situation is unexpected or
driver must make unusual maneuvers
or under difficult-to-perceive
situations
• Requires higher P/R time
• Depends on type of maneuver
made and roadway setting (urban vs.
rural)
• Use table 3.5 from Text, page 75
303
Decision
(controlled stop, speed/path/route change) – DSD (Table 3-3)
Source: A
Policy on
Geometric
Design of
Highways and
Streets (The
Green Book).
Washington,
DC. American
Association of
State Highway
and
Transportation
Officials, 2001
4th
Ed.
304
Passing Sight DistancePassing Sight Distance
Assumptions (conservative?):
1. Vehicle being passed travels at uniform speed
2. Speed of passing vehicle is reduced behind passed
vehicle as it reaches passing section
3. Time elapses as driver reaches decision to pass
4. Passing vehicle accelerates during the passing
maneuver and velocity of the passing vehicle is 10
mph greater than that of the passed vehicle
5. Enough distance is allowed between passing and
oncoming vehicle when the passing vehicle returns
to its lane
305
Source: A
Policy on
Geometric
Design of
Highways and
Streets (The
Green Book).
Washington,
DC. American
Association of
State Highway
and
Transportation
Officials, 2001
4th
Ed.
306
Passing Sight DistancePassing Sight Distance
Dpassing = d1 + d2 + d3 + d4
d1 = distance traveled during P/R time to point where
vehicle just enters the left lane
d1 = 1.47t1(u – m + at1)
2
where
t1 = time for initial maneuver (sec)
u = average speed of passing vehicle (mph)
a = acceleration (mph/s)
m = difference between speeds of passing and
passed vehicle
307
Passing Sight DistancePassing Sight Distance
Dpassing = d1 + d2 + d3 + d4
d2 = distance traveled by vehicle while in left lane
d2 = 1.47ut2
where:
u = speed of passing vehicle (mph)
t2 = time spent passing in left lane (sec)
308
Passing Sight DistancePassing Sight Distance
Dpassing = d1 + d2 + d3 + d4
d3 = clearance distance varies from 110 to 300 feet
d4 = distance traveled by opposing vehicle during passing
maneuver
d4 usually taken as 2/3 d2
309
Important Sight DistancesImportant Sight Distances
(cont.)(cont.)
4. Intersection (turning/crossing)
5. Crossing RR
1. Stop, proceed, proceed from stop
310
• Crossing
RR
• Stop,
proceed,
proceed
from stop
311
What are the key
variables?
312
Key issues in safe crossingKey issues in safe crossing
Speeds
D Distance from front of vehicle to driver’s eye
Dt Distance from rail to front of vehicle
Vv Assumptions about PR time and braking distance
W Width of crossing
D Distance from end of vehicle after crossing
L Length of vehicle
Acceleration capability of road vehicle
Offset of obstruction from the road and the rail line
313
HomeworkHomework
Go to the example on slide 24. Calculate the vehicle
speed if the roadway is gravel.
Next calculate the vehicle speed on the paved roadway,
but with snow and ice on the road (f = 0.30).
Show your work and discuss how much a driver should
reduce his/her speed for ice and snow on the paved road.

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Highway And traffic Engineering

  • 2. OverviewOverview • This course aims at providing the student an introduction to Transportation Engineering. The course is organized under five modules. These are: 2
  • 3. • Introduction to Transporation Systems Engineering • Transportation Planning • Geometric Design • Pavement Design • Traffic Engineering 3
  • 4. ObjectivesObjectives • Introduction to Transportation Systems Engineering • Objective of this module is to give an overview of the transportaion engineering. • The focus will be to present a systems approach where the interaction of humans and the vehicles and their impact on the society and transportation. 4
  • 5. ObjectivesObjectives • Transportation Planning plays an important role in a region's strategy to improve the performance of the transportation system. • Objective of this module is to describe the basic characteristics of transportation planning and of the models used by transportation planners. 5
  • 6. ObjectivesObjectives • Geometric Design of highways deals with the dimensions and layout visible features such as, alignment, sight distances and intersections. • Objective of this module is to describe highway design objectives, constraints and controlling factors, also to describe the criteria, standards and engineering procedures used to design principal elements of the highway alignment, and highway cross sections. 6
  • 7. ObjectivesObjectives • Pavement Design based on empirical and mechanistic relations between materials, geometry and performance. • Objective of this module is to understand the process of collecting information necessary for successful design of flexible and rigid pavements, including traffic data, material properties and other environmental factors. 7
  • 8. ObjectivesObjectives • Traffic Engineering includes traffic signs, markings, traffic signals, islands etc. • Objective of this module is to understand the basic parameter of traffic engineering and the methods to estimate those parameters. • It examines ways to promote operational efficiency and safety through the use of traffic control devices. 8
  • 9. 9 S. # TOPICS Lecture Required 01 Transportation system: Introduction 1 02 Evolution of Transportation /Highway Development in Pakistan 1 03 Highway planning 1 04 Geometric design: Introduction/ Design controls 1 05 Design vehicle 1 06 Functional classification of roads and Design speed 1 07 Design Driver 1 08 Design Volume 1 09 Sight Distances 3 10 Cross section elements (with of travel lane, shoulders, medians ……) 2 MEHRAN UNIUVERSITY OF ENGINEERING AND TECHNOLOGY RM-001/00QSP-004 Dec.01.2001 TENTATIVE TEACHING PLAN DEPARTMENT/INSTITUTE/DIRECTORATE: CIVIL ENGINEERING Name of Teacher: Prof. Dr. Abdul Sami Qureshi Subject: Highway & Traffic Engineering Batch: 08CE- Year: Final Term: 1st Term Starting Date: 03-01-2011 Term Suspension Date: 24-04-2011
  • 10. 10 09 Cross slopes 1 10 Horizontal Alignments: Introduction 1 11 Horizontal curves 2 12 Transition, curves 2 13 Super-elevation 2 14 Curve widening 1 15 Vertical Alignments: Introduction 1 16 Grades 1 17 Vertical curves 2 18 Pavement Design: Introduction 1 19 Early road construction methods 1 20 Design of flexible design 4 21. Design of rigid pavement 4 22. Maintenance of pavement 2 23. Traffic Engineering: Introduction 2 24. Volume studies 2 25. Highway safety 3 26. Highway capacity 3 27. Traffic control devices 1 28. Traffic signals 3 TOTAL 52
  • 11. REFERENCESREFERENCES 1. HIGHWAY ENGINEERINGPAUL H. WRIGHT/ KAREN K. DIXON 1. TRANSPORTATION ENGINEERING C. JOTIN KHISTY-B. KENT LALL 1. HIGHWAY ENGINEERING J. KHANNA 1. THE HAND BOOK OF HIGHWAY ENGINEERING T. F. FWA 1. http://nptel.iitm.ac.in/ 2. http://ocw.mit.edu/OcwWeb/web/home/home/in dex.htm 3. HIGHWAY CAPACITY MANUAL 11
  • 14. Transportation SystemTransportation System Definition of Transportation Modes • A transportation system is an infrastructure that serves to move people and goods efficiently. • Efficient = safe, rapid, comfortable, convenient, economical, environmentally compatible.
  • 15. Transportation SystemTransportation System Major transportation subsystems • Land transportation: highway, rail • Air transportation: domestic, international • Water transportation: inland, coastal, ocean • Pipelines: oil, gas, other
  • 17. MAJOR INTERACTING COMPONENTSMAJOR INTERACTING COMPONENTS InfrastructureInfrastructure Vehicle / ServiceVehicle / Service Users /Users / SubstanceSubstance
  • 18. Users / ContentUsers / Content • People → Passenger Transportation • Goods → Freight Transportation Shareoftotalpassengersor tons-km Distance Passengers Commuting Shopping Recreation Business Tourism Migration Waste disposal Local distribution Trade Energy & Raw Materials Freight Source: Dr. Jean-Paul Rodrigue, Dept. of Economics & Geography, Hofstra University.
  • 19. Users / substanceUsers / substance Passengers Freight Board, get off and transfer without assistance Must be loaded, unloaded and transferred Process information and act on it without assistance The information must be processed through logistics managers Make choices between means of transport often irrationally Logistics managers make choices between means of transport rationally Source: Dr. Jean-Paul Rodrigue, Dept. of Economics & Geography, Hofstra University.
  • 37. Evolution of TransportationEvolution of Transportation 2000 Maritime Road Rail Air 180019001950 Docks Locks RailsOmnibus Steam engine Electric motor Balloons Dirigibles Iron hulls Internal combustion engine Metro TramwayAutomobileLiners Bicycles PlanesTrucks Buses Electric car Hydrogen car Airfoils Super tankers TGV Maglev Jet engine Jet Plane Container ships Helicopters Bulk ships Highways Jumbo Jet
  • 38. Evolution of TransportationEvolution of Transportation 1500-1840 Average speed of wagon and sail ships: 16 km/hr 1850-1930 Average speed of trains: 100 km/hr. Average speed of steamships: 25 km/hr 1950 Average speed of airplanes: 480-640 km/hr 1970 Average speed of jet planes: 800-1120 km/hr 1990 Numeric transmission: instantaneous Source: Dr. Jean-Paul Rodrigue, Dept. of Economics & Geography, Hofstra University.
  • 39. Evolution of TransportationEvolution of Transportation 100 500 1000 1800 1900 20001850 1950 50 250 750 Stage Coach Rail Automobile HST Propeller Plane Jet Plane Liner Clipper Ship Containership Road Maritime Rail Air Km /hr
  • 40. Evolution of TransportationEvolution of Transportation • The TGV (French: Train à Grande Vitesse, meaning high-speed train) is France's high-speed rail service • A TGV service previously held the record for the fastest scheduled rail journey with a start to stop average speed of 279.4 km/h (173.6 mph),[2][3] which was surpassed by the Chinese CRH service Harmony express on the Wuhan–Guangzhou High-Speed Railway in 2009. • Maglev (magnetic levitation), is a system of transportation that suspends, guides and propels vehicles, predominantly trains, using magnetic levitation from a very large number of magnets for lift and propulsion. • A hydrogen vehicle is an alternative fuel vehicle that uses hydrogen as its onboard fuel for motive power • Buses, trains, motorcycles,, ships, airplanes, submarines, and rockets can already run on hydrogen, in various forms.The current land speed record for a hydrogen-powered vehicle is 286.476 mph (461.038 km/h) 40
  • 41. 41 • Now a days Supertankers has a length overall of 380.0 metres (1,246.7 ft) and a cargo capacity of 3,166,353 barrels (503,409,900 l).
  • 42. 42
  • 43. 43 A jet aircraft is an aircraft propelled by jet engines. Jet aircraft generally fly much faster than propeller-powered aircraft and at higher altitudes – as high as 10,000 to 15,000 meters (about 33,000 to 49,000 ft).
  • 44. 44 A jumbo jet is a term used to describe a large aircraft, most commonly the Boeing 747, after Jumbo, a famous elephant. The 747-400, is among the fastest airliners in service with a high- subsonic cruise speed of 570 mph, 920 km/h and can accommodate more than 500 passengers.
  • 45. What isWhat is TRANSPORTATIOTRANSPORTATIO N ENGINEERINGN ENGINEERING ??
  • 46. Transportation EngineeringTransportation Engineering • One of the specialty areas of civil engineering – Development of facilities (roads , railways, airports, Bus stops,..) for the movement of goods and people – Planning, design, operation and maintenance • Multidisciplinary study
  • 47. • Transportation engineering: • Science deals with efficient, safe, economical, comfortable and speedy movement of goods and persons. • • Highway Engineering: • It covers the construction of roads and providing the facilities to road user and planning for safety or road vehicles etc. • • Railway Engineering: • It deals with the lying of the railway track for movement of heavy locomotives, wagons etc. it deals also with control of movement with help of station yards. • 47
  • 48. • River and Harbour Engineering: • Science deals with the development of docks and harbour on sea or river shore for departure and arrival of ships and other facilities for loading, unloading etc. • • Airport Engineering: • Technique of development of runways, taxiways, hanger, terminal building and control devices etc are dealt in Airport engineering. 48
  • 50. Transportation EngineeringTransportation Engineering • An interesting / exciting area ! • Employers – 50% government – 40% consultants – 5% research, teaching – 5% other rail, trucking firms, etc.
  • 52. Development of road:Development of road: • Road extensively used before advent of railways • Major roads work ignored but attention on feeder roads. • End of 2nd world war provided surplus military vehicles of civilization. • Boom to road construction and 1930 -- automobile age • • Highway related activities: – motor vehicle registration – highway expenditures – road milage pass-Km, Tonn – Km. – motor fuel consumption…. 52
  • 53. • Infrastructure and Economic • Growth • 􀂄 In the following slide a graph is presented that clarifies the role of • infrastructure in economic development (Source: Queiroz et al, 1992 • – World Bank Working Paper). • 􀂄 This slide shows a plot of the length of paved roads that a country • has versus its GNP • 􀂄 98 countries were surveyed to plot this graph • 􀂄 A clear correlation emerged between the Length of paved roads 53
  • 54. • (LPR) and the per-capita GNP (PGNP) according to the following • equation • 􀂄 PGNP = 1.39 (LPR) • 􀂄 This indicates that the more physical infrastructure a country has (in • this example we consider only transportation infrastructure, but this • relationship holds true for other types of infrastructure as well), the • greater the economic stability and vice versa. 54
  • 55. 55
  • 56. The Infrastructure CrisisThe Infrastructure Crisis • Despite the importance of infrastructure for economic and social well-being, we are faced with several problems • Infrastructure in developed countries is old, unreliable, inefficient and in need of replacement. • 􀂄 The USA is embarking on a major plan relating to infrastructure spending • 􀂄 In developing countries, infrastructure is often not available 56
  • 57. • 􀂄 Large portions of urban and rural populations in developing countries haveinadequate access to water and sanitation • 􀂄 Power supply is non-existent or unreliable and people are faced with frequent power-cuts • 􀂄 Quality of road infrastructure is often bad, leading to long travel times and increased vehicle maintenance costs. Width of roads is also often a constraining factor leading to traffic jams and blocks. • 􀂄 Several of these problems currently hold true for many areas in India as well. • 􀂄 This is therefore a golden opportunity for engineers with technical as well as managerial and policy level knowledge of these issues, since there is a huge demand for such people to enter the workforce and solve the worlds infrastructure inadequacies. 57
  • 58. Why do we have so manyWhy do we have so many problems with infrastructure?problems with infrastructure? • 􀂄 This particular question and ways in which to solve it will • the focus of this entire course. It is therefore impossible • to answer this question right away. Before we conclude • this session, we list out a few of the causes for the failure • to provide adequate infrastructure • 􀂄 Lack of funds • 􀂄 Lack of implementation and management capabilities • 􀂄 Corruption, bureaucracy and unfair competition • 􀂄 Land acquisition issues involving dealing with displaced people • and special interest groups • 􀂄 etc 58
  • 59. INTRODUCTIONINTRODUCTION PAKISTAN HIGHWAY SYSTEMPAKISTAN HIGHWAY SYSTEM PAKISTAN TRANSPORTATION SYSTEM  It contributes 11% in country's GDP & 5.46 % in employment labor force  It accounts for 90% passenger and 96% for freight traffic.  Road transport is to be Considered the backbone of Pakistan transport.  It Carries about 80% of the Pakistan total transport.
  • 60. 60 Passenger Transportated in Pakistan 2% 16% 82% 1 2 3 82% through Roadways 16% through Railways 2% with Airways
  • 61. 61 82 16 2 0 20 40 60 80 100 1 2 3 Cargo Transported in Pakistan
  • 62. PAKISTAN HIGHWAYPAKISTAN HIGHWAY SYSTEMSYSTEM • 1947 – 49959Km • 9759 Km (High type) • 40200 Km (Low type... Earthen) • • 1985 – 118211 Km 5160 Km (High type) Growth Rate 2.29%→ • 1998 – 180000 Km (urban as well as rural) • 2008-2009 -- 258,350 kms • 23 National Highways, 7 motorways, 3 expressways & 3 Strategic roads. • The length of high type road is 176,589kms and low type road is 81,761kms. • The total length of National Highways, Motorways, expressways and strategic roads is 11857kms. Which is 4.6% of total length. • Quite development but not satisfactory, when compared with other countries area and population wise. 62
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  • 97. 97 Country Length (Km) per 100 Km2 Length (Km) per 1000 Km2 Japan France USA Germany India Srilanka 274 174 64 168 50 38 >150 >120 -- >100 Pakistan 14 0.43 Pakistan Poorest Country Even India has 3 to 4 times greater Kilometerage
  • 98. 98 Lanes 1 Lane 2 Lane 2 – 3 Lane 3 – 4 Lane > 4 Lane 61% 29% 5% 4%
  • 99. Challenges For PakistanChallenges For Pakistan • Increased traffic volume due to increased vehicle ownership • Dire deficiency of 346000Km to serve people efficiently. • To widen existing road network from single lane to two • If 3000Km constructed every year even then require 100 years • Big potential for opportunities for Highway Engineers. 99
  • 100. Existing Challenges for PakistanExisting Challenges for Pakistan  Now- days over half the road is in poor condition and most of the roads has been failed before their design life. Failure is defined in terms of amount of cracking, rut depth, surface roughness, skid resistance or other indicators  The various factors which may cause the failure of pavement are:  Overloading  Unsatisfactory Compaction  Inadequate Drainage  Frost action  Quality of Material  The material used does not compliance the specification.  Laboratories do not follow the proper process in testing.  Equipments are not properly working.  End products are not according to specification and give less results as compared to the required.  This problem can be improved or partially solved by proper “Quality assurance in testing of highway materials”.
  • 102. Highway Planning:Highway Planning: • The making of plans and engineering investigation of the project on a scientific basis rather than haphazard for future Construction, maintenance and operation (Or for new project or explained programs) is called Highway Planning. • A summary of major Data required for Highway Planning are: • An inventory of all rural roads (Width type, condition and road bridges….) • An estimate of volume and character of traffic • Source of highway financing of the state and subdivision. • An estimate of the number of the motor vehicles ownership. • Road life studies based on past records of construction and reconstruction, from which service life can be estimated. • 102
  • 103. Object of Highway Planning:Object of Highway Planning:  The proposed road should provide efficient, safe, economical comfortable and speedy movements.  It should have maximum utility within available resources and other restraints.  It should meet for anticipated future developments and social needs.  Highway planning should evolve financing system and recommend changes in taxes and budget procedures.  Highway Planning helps in phasing the road development programs from financial consideration and top most needy condition. 103
  • 104. Principal of Highway Planning:Principal of Highway Planning: • Equipped with traffic sign boards or statutory provision for regulation • Importance of road should be only on traffic demand • Road should from integral part of network and form a part of development schemes. • There should be provision of maintenance funds 104
  • 105. Deficiencies of Highway planning:Deficiencies of Highway planning: • No correlation to transport needs. • No any base on systematic transport survey • No asses of base and horizon year traffic. • No evaluation for qualitative improvements in terms of geometric, structural integrity, riding surface etc. • No relation between transport plans with other sector like agriculture, industry etc. 105
  • 106. STUDIES/ DATA COLLECTIOINSTUDIES/ DATA COLLECTIOIN REQUIRED FOR EFFICIENT PLANNINGREQUIRED FOR EFFICIENT PLANNING • Field studies are conducted to collect the data for assessment of road length requirement for an area. • Intelligent approach for efficient planning • Helps in protecting any project from short sightedness and shifting policies • Detailed of surveys/studies are given below for the development of a road Project. 106
  • 107. ECONOMIC STUDIESECONOMIC STUDIES • Following details should be collected for economic studies to determine the details of services given by the proposed road to population & products of area which are useful in estimating the economics involved • Population and its distribution Trend of population growth • Agriculture and industrial production and their listing in classified groups and develop their future trends • Per capita income • Existing facilities like post office, School, Banks , etc (Regarding communication, education and recreation to estimate the Source of traffic) • Country Highway mileage, its condition and distribution. 107
  • 108. Financial Studies:Financial Studies: • It is important to study various financial aspects like source of income and their methods adopted to mobilize the fund for project • Source of income • Estimating revenue from road transport • Living standards • Resources from local level, toll, Vehicle registration and court fines etc. 108
  • 109. Traffic and road use studies:Traffic and road use studies: • Details of existing traffic, their volume and the pattern of flow etc is necessary to plan for improvement in road system or for construction of new road. • Traffic Volume per day, AADT and peak hourly traffic volume • Origin and destination study. • Mass transportation facilities • Accidents, their cost analysis and causes • Future trend and growth in traffic volume and goods traffic • Growth of passenger trips and trend in the choice of mode • Type of vehicle, gross weight, axle load, weight and length or vehicle , commodity hauled etc are value able for road design and regulation purpose 109
  • 110. Engineering Studies:Engineering Studies: • Detail of topography, Soil, Drainage and problems related to construction and maintenance to be investigated to chalk out plan. It needs • Topographic survey • Road location and alignment studies • Soil surveys • Location and classification of existing roads and their types • Road life studies, construction methods and maintenance problems • Special problems in drainage 110
  • 111. PROJECT REPORT:PROJECT REPORT: Project report should contain following details • Introduction of project along with history and graphical details • Main requirements and factor of proposed alignment • Details of alignment with respect to proposed width/ guage , gradients, length and levels of points • Description about other proposed alternatives • Details of proposed alignment with various dates and maps • Specifications of the constructional standards • Conclusion and recommendation of proposed project of new railway line / High way. 111
  • 112. Drawing to maps prepared along withDrawing to maps prepared along with project report:project report: • Overall map of that region to a scale 1 cm = 2Km. • Index map of the area to a scale of 1 cm = 2.5 Km. • detailed plan of proposed alignment with L section • Contour plans and L section at bridge & culvert • Plans of Bus stop to scale of 1 cm = 50 cm (Bus stop, Rest , filling stations, Rest places) • detailed drawing of all the bridges and buildings to a scale of 1 cm = 1 m • plan of level crossings to a scale 1 cm = 50 m • details of important structures lying with 300 m on either sides of the proposed rout • Cross section at every important point should be prepared. 112
  • 114. Geometric designGeometric design • Criterion for the Selection of best rout (Corridor Study). • Design of visible features 114
  • 115. Corridor StudyCorridor Study The objective of the corridor study (highway location study) is to establish highway's centerline (baseline) and cross-sections in relation to the terminal points and to the topography of the area through which the highway will pass. The proposed highway route must be: 1. Economically justifiable, 2. Technically feasible, and 3. Environmentally acceptable.
  • 116. 116 Basic Principles for HighwayBasic Principles for Highway LocationLocation • There are an infinite number of ways to get from point A to point B. • selecting the best path between two points is called Highway location • Visible features of a road are Straight section; Transition curve; Circular curve; Vertical curve; Cross-sections • Visible features Roadway must be connected with each other to design a road that provides for the easy flow of traffic, while meeting design criteria and safety standards. Garber and Hoel, 2002
  • 117. 117 Factors Considered in the Selection ofFactors Considered in the Selection of the best routthe best rout • Topography • Social and demographic characteristics (including land use patterns) • Terrain and soil conditions Garber and Hoel, 2002
  • 118. 118 Factors Considered in the LocationFactors Considered in the Location ProcessProcess • Directness of route • Serviceability of route to industrial and population areas • Crossing of other transportation facilities (roads, railroads, rivers) – Intersect other roads at right angle Garber and Hoel, 2002
  • 119. 119 Factors Considered in the LocationFactors Considered in the Location ProcessProcess • Environmental – Animal habitat – Location of recreational, historic and archeological sites – Noise, air, and water pollution Garber and Hoel, 2002
  • 120. 120 Factors Considered in the LocationFactors Considered in the Location ProcessProcess • Economic – Construction – Maintenance costs – Road user costs – Road user benefits (i.e. travel time) – Adverse effects such as dislocation of people or businesses Garber and Hoel, 2002
  • 122. ENGINEERING SURVEY FOR HIGHWAYENGINEERING SURVEY FOR HIGHWAY LOCATIONLOCATION • This survey is also called Route Survey and propose is to fix the final road alignment • and carried out in four stages. • Map study • Reconnaissance survey (Recci) Survey • Preliminary survey • Final location and detailed survey 122
  • 123. 123
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  • 130. Map Study:Map Study: • It suggests the possible routes of the projected road out of several likely alternative routes from available • It gives the rough guidance about the route to be further survey in the field • The main features likes rivers hills valleys etc available on maps helps in locating the alignment roughly avoiding ponds and lakes. • Give idea about approximate location of bridges, tunnels etc. • From map study it is also possible to drop a certain route due to unavoidable obstructions. • Topographic map having 15 or 30 meter contour intervals could be used for this study. 130
  • 131. :: Recci SurveyRecci Survey • The main object of Recci survey is to examine in the field the general characteristics of a stretch of land along the proposed alternatives routes marked on the map. • Following facts (not available in maps) are collected during recci survey. • e.g. Marshy land, ridge, hills, permanent structures and other type of cross drainage structures, soil type along the route, proximity of materials and labor etc. • For that survey plans, land use plans, air photos, stream and drainage maps etc. are used. • As a result of recci survey a few alternative alignment (two or three)may be chosen for further study. • Recci survey is not required for minor relocation of an existing road. 131
  • 132. Preliminary Survey:Preliminary Survey: • The preliminary survey decides the final route among two or three routes after studying the advantages and disadvantages. • It is carried about with great accuracy and with critical study • Because the final route selection depends upon it and has much effect on investment. • Generally preliminary survey work is more or less an open traverse survey of 60 to 300 meters wide belt along the centre line of proposed (2 or 3) alternatives. • 132
  • 133. Preliminary SurveyPreliminary Survey Preliminary Survey is done especially to collect below information • Geological information like soil, rocks, etc and their bearing capacity • Details of existing culverts, bridges, tunnels, irrigation canal works etc. • Position and details of level crossing proposed. • Availability of construction material, labors, water along proposed alignment. • H.F.L. and L.W.L. of all river streams on paved alignment. • Preliminary survey work is done mostly with Tachometer, Level instrument, Prismatic compass and Plane table. 133
  • 134. Preliminary SurveyPreliminary Survey • All physical features e.g. building, posts of existing roads and their radius of horizontal curves should be marked and measured from transverse line. • Grades at every 50m interval. • Cross section at every 500m intervals. • In order to have general idea to final centre line of alternative alignment conforming to the design standards is tried on plans. • More suited alternatives from economic and other consideration is finally chosen. 134
  • 135. Location Survey:Location Survey: • Here full detailed survey work will be done along most economical route, determined by the preliminary survey. • The final route marked on prepared plan is known paper location, in which details of gradient, curves, contour, direction crossing of streams etc are worked out. • Then transfer of alignment from paper to ground is done in the Final location Survey. 135
  • 136. Final Location SurveyFinal Location Survey • It consists in fixing up the centerline of the proposed highway on the ground with the horizontal and vertical controls. Final location involves two main operations. • Sketching out of final centerline of the field. • Beginning and end of circular and transition curves and all other intermediate transit points (250m C/C) should be fixed on center in case of new roads or by means of spikes in the case of existing road. • A single datum should be used for level works. • Permanent bench marks should be established at every 250m, and at all drainage structure or on famous reference point. 136
  • 137. Final Location SurveyFinal Location Survey – Detailed cross section at stations every 50m in plain and at 25m in rolling terrain apart should be taken. – In addition above other cross sections at the beginning, middle and at end of spiral and of circular curves should be taken up to the right-of-way limits. Detailed leveling. – Longitudinal profile should also be taken for a stretch at least 200m beyond then limit of the project. • After protecting the points referencing Centre line the construction survey is started. 137
  • 139. 139 HOW IS HIGHWAYHOW IS HIGHWAY LOCATION DETERMINED?LOCATION DETERMINED? When Your Land Is Needed For Highway Use Author: Stephen D. Holowach 7/23/99 http://www.119south.com/presentation/ • Establish the most direct and useable highway facility at the least possible cost to the public. • For undertakes intensive studies on several possible routes • Select the route that has the least possible inconvenience or injury to the public and the private landowner. • Analyze the data concerning the economy, population needs and traffic volume trends for the area under study. • Make the Aerial and ground surveys to consider factors such as safety, drainage and soil types. • Hold the public meetings to discuss the proposed alternate locations.
  • 140. 140 RIGHT-OF-WAY?RIGHT-OF-WAY? • Right-of-Way is the term used to describe the right to pass over another’s land. • When the government acquires land for Highway Purposes it is actually obtaining “Right-of-Way” over land on which a public road ultimately will be built. • It is a Constitutional right of the government to acquire land for public purposes • The every Department of Transportation will execute this right only when it will benefit the public.
  • 141. 141 What does a location study include?What does a location study include? http://www.virginiadot.org/projects/studybris-http://www.virginiadot.org/projects/studybris- coalfieldprocess.aspcoalfieldprocess.asp Fully defining the project, or "scoping“ •This process is an opportunity to identify issues and obtain comments from agencies, jurisdictions and the public early in the planning process. •A "purpose and need" statement and the goals and objectives of the Location Study will be developed.
  • 142. 142 What does a location study include?What does a location study include? (VDOT)(VDOT) http://www.virginiadot.org/projects/studybris-http://www.virginiadot.org/projects/studybris- coalfieldprocess.aspcoalfieldprocess.asp Alternatives Identification •Use technical data such as traffic counts and aerial mapping and early environmental evaluations to develop several possible road locations, or alternatives, within the Study corridor. •In this phase is to identify reasonable alternatives that consider the input provided from communities, businesses and individuals as well as regional concerns. •Consider a number of new locations as well as upgrades of existing roads. •Look at the deficiencies of the existing transportation network, including safety concerns and any planned improvements along the study corridor.
  • 144. 144
  • 147. 147 4 ACTIVITIES4 ACTIVITIES 1. The existing physical structure needs major repair/replacement (structure repair). http://www.k5kj.net/jarrell.htm
  • 148. 148 4 ACTIVITIES4 ACTIVITIES 2. Existing or projected future travel demands exceed available capacity, and access to transportation and mobility need to be increased (capacity). http://www.ens- newswire.com/ens/sep2002/2002-09-19- 06.asp
  • 149. 149 4 ACTIVITIES4 ACTIVITIES 3. The route is experiencing an inordinate number of safety and accident problems that can only be resolved through physical, geometric changes (safety). http://www.ems.ucla.edu/traffic/ ta10.htm
  • 150. 150 4 ACTIVITIES4 ACTIVITIES 4. Developmental pressures along the route make a reexamination of the number, location, and physical design of access points necessary (access).
  • 152. Geometric DesignGeometric Design • Geometric design is the aspect of transportation engineering that deals with • A) Selection of the best path between two destinations. • B) Deals with the design of visible features of a road • A good geometric design has to balance balance operational efficiency, comfort, safety, convenience, cost, environmental impact, and aesthetics. 152
  • 153. Geometric DesignGeometric Design • Geometric design deals with the design of visible features • Visible features are – Straight section – Transition curve – Circular curve – Vertical curve – Cross-sections 153
  • 171. Design ControlsDesign Controls Factors which control the visible features of the Highway • Design vehicle • Design speed • Design volume • Design driver • Sight distance • Highway classification………. 171
  • 173. DesignDesign VehicleVehicle A design vehicle represents an individual class in a conservative manner. • passenger cars (compact, subcompact, light delivery trucks), • trucks (single-unit, tractor-semitrailer combinations, trucks with full trailers), • buses/recreational vehicles (single- unit, articulated, school buses, motor homes, passenger cars pulling trailers or boats).
  • 174. 174 Design VehicleDesign Vehicle • Design Vehicle – largest (slowest, loudest?) vehicle likely to use a facility with considerable frequency • Three characteristics that affect almost all aspects of highway design – Physical – Operating – Environmental
  • 175. 175 Physical CharacteristicsPhysical Characteristics • Type (GB defines 20 design vehicle types) – Passenger Car P – Buses B – Trucks SU, WB – RVs – Farm tractor • Size – Length – Height – Weight – Width – Height of driver’s eye (car: 3.5’ – avg., truck: 7.6’ – high side) – Center of mass
  • 176. 176
  • 177. Minimum Turning PathMinimum Turning Path Passenger CarPassenger Car Minimum turning path is defined by the outer trace of the front overhang and the path of the inner rear wheel.
  • 184. 184
  • 185. 185 Dimensions of Design Vehicle TypesDimensions of Design Vehicle Types
  • 186. 186 Operating CharacteristicsOperating Characteristics • Acceleration • Deceleration and braking • Power/weight ratios • Headlights • Friction (ball bank)
  • 187. 187 EnvironmentalEnvironmental CharacteristicsCharacteristics • Noise (noise meter) • Exhaust • Fuel Efficiency • Dust (particulate and VOCs from tires and brakes)
  • 188. Vehicle PerformanceVehicle Performance Characteristics acceleration deceleration difficulties in maintaining steady speed Use intersections freeway ramps climbing or passing lanes, and turnouts for buses
  • 191. Vehicles on GradesVehicles on Grades • Passenger cars – The upgrades up to 3% have a slight impact on passenger cars. – On steeper grades this effect becomes more pronounced. – No special consideration is needed. • Trucks – The effect of grades on truck speeds can be quite strong (Exh. 3-53, 3-60). – The truck with the mass/power ratio 120 kg/kW is selected to represent heavy vehicles (conservative assumption). • Recreational vehicles – Consideration of recreational vehicles on grades can be justified for recreational roads with the low percent of trucks (for example, to consider an additional lane).
  • 192. Effect of grade on truckEffect of grade on truck performanceperformance Crawling speed
  • 193. Effect of differential speedEffect of differential speed on crash rateon crash rate
  • 194. Critical Lengths of GradesCritical Lengths of Grades
  • 195. 195 Effect of grade on RVEffect of grade on RV performanceperformance
  • 196. Maximum Side FrictionMaximum Side Friction Exhibit 3- 11
  • 198. Design SpeedDesign Speed Design VolumeDesign Volume 198
  • 199. 199 Design Speed andDesign Speed and Design TrafficDesign Traffic ConceptsConcepts
  • 200. 200 ObjectivesObjectives  Get familiar with design speeds for functional classes  Describe traffic demand and determine for roadway design  Define ADT, AADT, DHV, D, DDHV, K-Factor, and T
  • 201. 201 • Posted speed = speed limit • Operating speed = free flow (spot speed) • Running speed = length of highway section ÷ running time • Design speed = selected speed used to determine geometric design features
  • 202. Design speedDesign speed • Design speed is the single most important factor that affects the geometric design. • It directly affects the sight distance, horizontal curve, and the length of vertical curves. • Since the speed of vehicles vary with driver, terrain etc, a design speed is adopted for all the geometric design. • Design speed is defined as the highest continuous speed at which individual vehicles can travel with safety on the highway when weather conditions are conducive. 202
  • 203. Design speedDesign speed • Design speed is different from the legal speed limit which is the speed limit imposed to curb a common tendency of drivers to travel beyond an accepted safe speed. • Design speed is also different from the desired speed which is the maximum speed at which a driver would travel when unconstrained by either traffic or local geometry. 203
  • 204. Design speedDesign speed • Since there are wide variations in the speed adopted by different drivers, and by different types of vehicles, design speed should be selected such that it satisfy nearly all drivers. • At the same time, a higher design speed has cascading effect in other geometric designs and thereby cost escalation. • Therefore, an 85th percentile design speed is normally adopted. • This speed is defined as that speed which is greater than the speed of 85% of drivers. In some countries this is as high as 95 to 98 percentile speed. 204
  • 205. 205 Design SpeedDesign Speed  Design speed is defined by the AASHTO Green Book as: ...the maximum safe speed that can be maintained over a specified section of highway when conditions are so favorable that the design features of the highway govern.  Design Speed should: 1) “…be consistent with the speed the driver is likely to expect.” and 2) “. . .fit the travel desires and habits of nearly all drivers.”  Not posted speed and not operating speed (but ALWAYS higher than both)  See first part of: http://www.fhwa.dot.gov/environment/flex/c h04.htm (Chapter 4 from FHWA’s Flexibility in Highway Design)
  • 206. 206 Design Speed ConsiderationsDesign Speed Considerations • Functional classification of the highway • Character of the terrain • Density and character of adjacent land uses • Traffic volumes expected to use the highway • Economic and environmental considerations
  • 207. 207 Design Speed in Green BookDesign Speed in Green Book (suggested minimum design speed)(suggested minimum design speed) Rural Local Roads Source: A Policy on Geometric Design of Highways and Streets (The Green Book). Washington, DC. American Association of State Highway and Transportation Officials, 2001 4th Ed.
  • 208. 208 Design Speed in Green BookDesign Speed in Green Book (suggested minimum design speed)(suggested minimum design speed) Rural Collectors Source: A Policy on Geometric Design of Highways and Streets (The Green Book). Washington, DC. American Association of State Highway and Transportation Officials, 2001 4th Ed.
  • 209. 209 Design Speed in Green BookDesign Speed in Green Book (suggested minimum design speed)(suggested minimum design speed) Rural Arterials  60 – 120 kph (40-75 mph)  Depends on … Terrain Driver expectancy Alignment (reconstruction)
  • 210. 210 Design Speed in Green BookDesign Speed in Green Book (suggested minimum design speed)(suggested minimum design speed) Urban • Locals 20-30 mph • Collectors 30 mph+ • Arterials 30-60 mph
  • 211. 211 Values represent the minimum acceptable design speeds for the various conditions of terrain and traffic volumes associated with new or reconstructed highway facilities
  • 214. 214 Traffic DefinitionsTraffic Definitions • Volume: – number of vehicles, pedestrians, etc. passing a point during a specific period of time – for vehicles, usually expressed as veh/hour (vph) or veh/hour/lane (vphpl)
  • 215. 215 • Demand: – number of vehicles, pedestrians, etc. that desire to travel between locations during a specific period – Frequently higher than volume during certain peak times – Trips are diverted or not made when there are constraints in the system – difficult to measure actual demand because capacity constrains the demand • Capacity: – maximum number of vehicles that can pass a point during a specific period – A characteristic of the roadway or facility
  • 216. 216 Characteristics of Traffic FlowCharacteristics of Traffic Flow • Highly variable – Time of day – Day of week – Season – Road characteristics – Direction
  • 218. 218 Volume StudiesVolume Studies • AADT: Annual average daily traffic (counted for 365 days) • ADT: average daily traffic (counted for > 1 day and < 365) • PHV: peak hour volume • Classification counts: fleet mix
  • 219. 219 Estimating AADTEstimating AADT • Annual Average Daily Traffic • Use count station information • Extrapolate to non-count locations • Used to adjust ADT for – Seasons – Daily variation
  • 220. 220 AADT Data Helps to:AADT Data Helps to: • Estimate highway revenues • Establish overall volume trends • Establish annual accident rates • Analyze benefits of road improvements
  • 221. 221 Counting ProgramCounting Program • To satisfy the traffic volume data needs for all roads under a particular jurisdiction, we establish a Counting Program A systematic pattern of counting at different times and locations
  • 222. 222 Traffic Counts MapsTraffic Counts Maps http://www.iowadotmaps.com/msp/traffic/index.html
  • 224. 224 Design VolumeDesign Volume • Usually hourly volume • Which hour? – Average hourly volume – inadequate design – Maximum peak hour – not economical – Hourly volume used for design should not be exceeded very often or by very much – Usually use 30th highest hourly volume of the year – On rural roads 30 HHV is ~ 15% of ADT – Tends to be constant year to year
  • 225. 225 Traffic DemandTraffic Demand  Design Hourly Volume (DHV) – future hourly volume (both directions) used for design - typically 30th HHV (highest hourly volume) in the design year  Why 30th HHV?  Breakpoint of 2-28  Compromise: too high is wasteful, too low poor operation  Approximately median weekly peak hour volume (top highest week peak hours) (30th HHV exceed 29 times in year)
  • 226. 226 Traffic Demand (cont.)Traffic Demand (cont.) 3. Exhibit 2-28 relationship between HHV and percent of ADT in peak hour (referred to as K-factor) Source: A Policy on Geometric Design of Highways and Streets (The Green Book). Washington, DC. American Association of State Highway and Transportation Officials, 2001 4th Ed.
  • 227. 227 Design Hourly VolumeDesign Hourly Volume DHV is a representation of peak hour traffic, usually for the future, or horizon year K-factor represents proportion of AADT that occurs in the 30th HHV K-factor = __DHV x 100 AADT K = 8 to 12% urban, 12 to 18% rural
  • 228. 228 Design Hourly Volume (Example)Design Hourly Volume (Example) If AADT is 3500 vpd and the 30th highest hourly volume for the year is 420 vph what is the K-factor for that facility? K-factor = __DHV x 100 AADT K-factor = __420 x 100 = 12 3500
  • 229. 229 Question: What’s the impact of choosingQuestion: What’s the impact of choosing different K factor for design?different K factor for design? If AADT is 3500 vpd, how will the design volume differ for K- factor = 8% vs. 12%? DHV = K-factor x AADT 100 DHVk=8% = 8 x 3500 = 280 vph 100 DHVk=12% = 12 x 3500 = 420 vph (diff of 140 100 veh)
  • 230. 230 Traffic Demand (cont.)Traffic Demand (cont.) • D = directional distribution = one way volume in peak direction (expressed as a percentage of two- way traffic) Rural 55 to 80% • Can also adjust for how traffic is distributed between lanes (e.g., 3 lanes, highest/outside lane may be 40% of total directional flow)
  • 231. 231 Directional DistributionDirectional Distribution (example)(example) If traffic is directionally split 60/40, what is directional distribution of traffic for previous example (Design hourly volume = 420 veh/hr)? Directional Design Hourly Volume (DDHV) = 0.6 x 420 = 252 veh/hr Notice we use 0.6 not 0.4!!
  • 232. 232 Traffic Demand (cont.)Traffic Demand (cont.) • T = percentage of heavy vehicles during design hour (Iowa interstate 35% plus) • Affects capacity, ability to pass on two- lane rural roads, etc. • Larger, occupy more space • Should determine % during design hour (truck patterns may not be same as passenger vehicles)
  • 233. 233 PHF = peak-hour volume 4(peak 15-min volume) Flow is not uniform throughout an hour HCM considers operating conditions during most congested 15-minute period of the hour to determine service level for the hour as a whole Peak Hour Factor (PHF)Peak Hour Factor (PHF)
  • 234. 234 Peak Hour FactorPeak Hour Factor
  • 235. 235 DHV = Peak-Hour Volume PHF Example Peak hour volume from previous = 375 vph PHF = 0.625 DHV = 375 = 600 vph 0.625 Note: the traffic you design for is the busiest 15 minutes during the peak hour … another way to think of it is 150 vehicles per 15 minutes = 600 vehicles per 60 minutes
  • 236. 236
  • 238. 238 Design DriverDesign Driver CharacteristicsCharacteristics • Design Driver: driver most expected to use facility (familiar or unfamiliar?) – Accommodated in design, signing, etc.
  • 239. 239 Design Driver CharacteristicsDesign Driver Characteristics Cont.Cont. • Physical characteristics • Processing ability • Tolerable Accelerations/Decelerations – Longitudinal (along roadway ) – Lateral (around curves) – Vertical (comfort)
  • 240. 240 Design Driver CharacteristicsDesign Driver Characteristics Cont.Cont. • Others?: age, gender, physical condition (alcohol, etc.), mental capabilities, skill (self perception – are you in the top ½ of driver skill?) • Two others related to design: perception-reaction time and expectancy
  • 241. 241 Design DriverDesign Driver • Wide range of system users • What range of drivers use the system? – Ages: 16 year old to 80 year old – Different mental and physical states – Physical (sight, hearing, etc) – experience • Design Driver: driver most expected to use facility
  • 244. 244 Visual ReceptionVisual Reception • Visual Acuity: Ability to see fine details • Static (stationary objects): –Depends on brightness –Increases with increasing brightness up to ~ 3 candles (cd/sq ft) -- remains constant after that –Contrast –Time (0.5 to 1.0 second) • Dynamic (ability to detect moving objects) –Clear vision within a conical angle 3 to 5º –Fairly clear within 10 to 12º –Key criteria in determining placement of traffic signs
  • 245. 245 Visual ReceptionVisual Reception • Peripheral Vision: Ability to see objects beyond the cone of clearest vision (160 degrees) – Age dependent – Objects seen but details and color are not clear
  • 246. 246 Visual ReceptionVisual Reception • Color Vision: Ability to differentiate one color from another – Lack of ability = color blindness – Combinations to which the eye is the most sensitive • Black and white • Black and yellow y in determining traffic signs colors
  • 247. 247 Visual ReceptionVisual Reception • Depth perception – Ability to estimate speed and distance •Passing on two-lane roads •Signs are standardized to aid in perceiving distance
  • 248. 248 Hearing Hearing perception – Ability to detect warning sounds – Sirens, horns
  • 250. 250 Perception-Reaction ProcessPerception-Reaction Process • Perception • Identification • Emotion • Reaction (volition) PIEV Used for Signal Design and Braking Distance
  • 251. 251 Perception-Reaction ProcessPerception-Reaction Process • Perception – Sees or hears situation (sees deer) • Identification – Identify situation (realizes deer is in road) • Emotion – Decides on course of action (swerve, stop, change lanes, etc) • Reaction (volition) – Acts (time to start events in motion but not actually do action) • Foot begins to hit brake, not actual deceleration
  • 252. 252 Typical Perception-Reaction time range is: 0.5 to 7 seconds Affected by a number of factors. What are they?
  • 253. 253 Perception-Reaction TimePerception-Reaction Time FactorsFactors • Environment: • Urban vs. Rural • Night vs. Day • Wet vs. Dry • Age • Physical Condition: • Fatigue • Drugs/Alcohol • Distractions
  • 254. 254 Perception-Reaction TimePerception-Reaction Time FactorsFactors • medical condition • visual acuity • ability to see (lighting conditions, presence of fog, snow, etc) • complexity of situation (more complex = more time) • complexity of necessary response • expected versus unexpected situation (traffic light turning red vs. dog darting into road)
  • 255. 255
  • 256. 256 Perception Reaction Time (PRT)Perception Reaction Time (PRT) • Time from Perception to Initial Reaction to Stimulus (Example)
  • 257. 257 AgeAge • Older drivers – May perceive something as a hazard but not act quickly enough – More difficulty seeing, hearing, reacting – Drive slower
  • 258. 258 AgeAge • Younger drivers – May be able to act quickly but not have experience to recognize things as a hazard or be able to decide what to do – Drive faster – Are unfamiliar with driving experience – Are less apt to drive safely after a few drinks – Are easily distracted by conversation and others inside the vehicle – May be more likely to operate faulty equipment – Poorly developed risk perception – Feel invincible, the "Superman Syndrome” Human Factors - Perception and Reaction by Joseph E. Badger. jebadger@harristechnical.com
  • 259. 259 AlcoholAlcohol • Affects each person differently • Slows reaction time • Increases risk taking • Dulls judgment • Slows decision-making • Presents peripheral vision difficulties Human Factors - Perception and Reaction by Joseph E. Badger. jebadger@harristechnical.com
  • 260. 260 ExperienceExperience • Even NASCAR drivers practice Familiarity Faster on familiar Unfamiliar more distracted – Rental car on unfamiliar road at 10 pm when it starts to rain (What is the driver doing?)
  • 261. 261 WeatherWeather • Fog • Rain • Ice • Snow • affects ability to see (snow, fog) • changes ability to stop (ice, snow, wet)
  • 264. 264
  • 265. 265 UnderstandingUnderstanding • Most people do not reduce speed in a work zone until they actually see activity • Only 78% of drivers in a study understood what “Lane Ends” mean • Many people, especially older drivers, don’t understand meaning of left turn displays Human Factors - Perception and Reaction by Joseph E. Badger. jebadger@harristechnical.com
  • 266. 266 FatigueFatigue • Increases perception/reaction time • Study by American Automobile Association found that in 221 truck accidents only 18.4% of the drivers had been driving less than nine hours. • 41% of truck accidents Human Factors - Perception and Reaction by Joseph E. Badger. jebadger@harristechnical.com
  • 267. 267 Dp = 1.47(V)(t) where: Dp = Distance traveled during PIEV process (feet) V = velocity (mph) t = perception-reaction time = 2.5s
  • 268. 268 How much longer does it take an impaired driver to perceive/react than an unimpaired one at 65 mph? Unimpaired has P/R time of 2.5 seconds Dp = 1.47(V)(t) = 1.47(65 mph)(2.5 sec.) ~ 240 feet Impaired Driver has P/R time of 4 seconds Dp = 1.47(65 mph)(4 sec) ~ 380 feet Difference is 380 – 240 = 140 feet Difference is safety and economic problem! Example
  • 269. 269 Perception/ReactionPerception/Reaction ApplicationsApplications • Stopping sight distance • Passing sight distance • Placement of signs/traffic control devices • Design of horizontal/vertical curves
  • 271. 271 Driver ExpectancyDriver Expectancy • Expectancy (def) – an inclination based on previous experience to respond in a set manner to a roadway, traffic, or information situation • Types – A Priori – long-term (based on collective past experience) PRT = 0.6s avg., some 2.0s – Ad Hoc – short-term (based on site- specific practices/situations encountered during a particular trip on a particular roadway, PRT = 1.0s avg., some 2.7s
  • 272. 272 Driver ExpectancyDriver Expectancy • Driver Expectancies (what do we expect as drivers?) – Specific colors (red = stop) – Driver ahead not to decelerate rapidly – Slower drivers in left lane – Work zone signs = people working – Lane size – Etc.
  • 273. 273 Selection ofSelection of Design DriverDesign Driver
  • 274. 274 Design criteria must be based on the capabilities and limitations of most drivers and pedestrians
  • 275. 275 The 85th percentile is generally used to select Design Criteria The 95th percentile or higher is used where the consequences of failure are severe AASHTO recommends 2.6 seconds for stopping sight distance (90th )
  • 276. 276 RRole of Transportationole of Transportation EngineerEngineer • allow proper sight distance in design, sign placement • avoid hitting driver with too much info at once – one sign at a time • clarity (sign size, color, reflectivity)
  • 277. 277 Driver Activities in Selection ofDriver Activities in Selection of PathPath • Control (overt actions) – Road Edge – Avoid a Car • Guidance (decisions) – Lane Placement – Car Following – Passing
  • 278. 278 Driver Activities in Selection ofDriver Activities in Selection of Path Cont.Path Cont. • Navigation Level (planning) – Maps – Observe a directional sign
  • 280. 280 Important Sight DistancesImportant Sight Distances 1. Stopping 2. Decision 3. Passing 4. Intersection 5. Crossing RR FIRST AND THIRD WILL BE DISCUSSED HERE
  • 281. 281 Sight Distance in DesignSight Distance in Design • For safety, should provide sight distance of sufficient length so that drivers can control the operation of their vehicles to avoid striking an unexpected object in the traveled way - STOPPING SIGHT DISTANCE (SSD) • Certain 2-lane roads should have sufficient sight distance to enable drivers to occupy the opposing traffic lane for passing other vehicles without risk of crash - PASSING SIGHT DISTANCE (PSD)
  • 282. 282 Green Book (AASHTO)Green Book (AASHTO) Policy QuestionPolicy Question • Sight distance assumes drivers are traveling at: – A. The posted speed limit – B. 10 mph above the speed limit – C. The 85% percentile spot speed of the facility – D. The design speed of the facility
  • 283. 283 Design Policy - ResponseDesign Policy - Response • Sight distance assumes drivers are traveling at: – A. The posted speed limit – B. 10 mph above the speed limit – C. The 85% percentile spot speed of the facility – D. The design speed of the facility
  • 284. 284 GB Question with responseGB Question with response • Stopping sight distance is composed of two distances, what are they? – Distance traveled during perception/reaction time – Distance required to physically brake vehicle
  • 285. 285 Studies onStudies on Perception/Reaction TimePerception/Reaction Time • 321 drivers (Johansson and Ruma): drivers expected to use brakes – Median: 0.66 sec – 90th percentile: >= 1.5 sec • Unexpected, response time increased by ~ 1 sec • Some drivers took over 3.5 seconds to respond even under simple test condition
  • 286. 286 GB QuestionGB Question • AASHTO GB recommends 2.5 seconds, this is adequate for conditions that are more complex than the simple conditions used in laboratory and road tests.
  • 287. 287 Sight distanceSight distance Distance a driver can see ahead at any specific time Must allow sufficient distance for a driver to perceive/react and stop, swerve etc when necessary
  • 288. 288 Stopping Sight DistanceStopping Sight Distance (SSD)(SSD)  Required for every point along alignment (horizontal and vertical) – Design for it, or sign for lower, safe speed  Available SSD = f(roadway alignment, objects off the alignment, object on road height  SSD = PRT + BD (with final velocity V2 = 0)
  • 289. 289 Criteria for Sight DistanceCriteria for Sight Distance • Driver eye height: for passenger vehicle’s = 3.5 ft above surface • Height of object in roadway = 2 feet (SSD) • Height of opposing vehicle = 3.5 feet (PSD)
  • 290. 290 Deceleration rate: AASHTO: 11.2 ft/s2 Deceleration is within capability of drivers to stay within their lane and control the vehicle when braking on wet surfaces and is comfortable for most drivers • AASHTO represents friction as a/g which is a function of the roadway, tires, etc • Can use when deceleration is known (usually not)
  • 291. 291 BD = V2 30[ (a) ± G] (g) Where: BD = braking distance (ft) V = speed (mph) (can also be “u”) a = deceleration rate (ft/s2 ) G = grade (decimal) g = acceleration due to gravity =32.2 ft/s2
  • 292. 292 Braking DistanceBraking Distance Assumes a rate of deceleration, driver may brake harder a = 11.2 ft/sec2 normal a = 14.8 ft/sec2 emergency, use tables from AASHTO Friction is a function of pavement condition (wet, icy), tire, and roadway surface Depends on weight, but some assumptions are made to arrive at a standard equation
  • 293. 293 SSD EquationSSD Equation SSD = 1.47ut + _____u2 _____ 30({a/g} ± G) SSD in feet u speed in mph (may also see “v”) t perception/reaction time (in seconds) a assumed deceleration rate (ft/sec2 ) g gravitational force (32.2 ft /sec2 ) G gradient in ft/ft
  • 294. 294 SSD ExampleSSD Example Use basic assumptions to determine SSD at 60 mph on a) 0% grade, b) 3% grade SSD = 1.47u(2.5 sec) + ________u2 ________ 30({11.2/32.2} + 0.00) SSD = 220.5 + 345.5 = 556 ft (compare to table 3-1 in GB – See next slide) On a +3% grade, SSD = 220 +318 = 538 ft
  • 295. 295 Stopping (emergency) – SSD (Table 3-1) Source: A Policy on Geometric Design of Highways and Streets (The Green Book). Washington, DC. American Association of State Highway and Transportation Officials, 2001 4th Ed.
  • 296. 296 SSD ExampleSSD Example Given: Available Sight distance = 430’ on a +3% grade Find maximum speed if perception reaction time is assumed to be 2.5 seconds 430 feet = 1.47u(2.5 sec) + ________u2 ________ 30({11.2/32.2} + 0.03) 430 feet = 3.68u + ________u2 ________ 30(0.378) Solving for u, u = 52.0 mph (Set speed at 50 mph) Discuss: Would this be an acceptable condition if the road is generally posted for 60 mph?
  • 297. 297 Stopping Sight DistanceStopping Sight Distance ExampleExample Consider analysis when vehicle skids across different surfaces (a/g is not equal to 0.35) Or final velocity is not zero at the end of the skid, as evidenced because the vehicle sustains crushing damage until the vehicle is stopped.
  • 298. 298 Stopping Sight DistanceStopping Sight Distance where: terms are as before, except vo = original velocity vf = final velocity at impact With assumed acceleration, using friction S = PRD + Db = 1.47vot + vo2 - vf2 30(f ± G)
  • 299. 299 Stopping Sight DistanceStopping Sight Distance ExampleExample Accident Reconstruction: Average Skid Mark = 47 feet Crush damage indicates 20 to 30 mph speed at impact f = 0.65 (how do they know this?), level roadway, and 40 mph posted speed. Was vehicle speeding? 47 feet skid represents what? BD? If final speed is 30 mph … BD = 47 = (Vi 2 – 302 )/30(0.65 + 0) Vi = 42.6 mph If final speed is 20 mph (Vi = 36.3 mph) What if pavement changes to gravel after 47 feet and car slides another 30 feet (f = 0.7)? What is initial speed?
  • 300. 300 Typical values for frictionTypical values for friction Values of friction vary widely with road surface type, age, condition. Examples: Surface type f (or a/g) Concrete pavement -dry 0.60 to .75 Concrete pavement – wet 0.45 to .65 Asphalt pavement 0.55 to .70 Gravel 0.40 to .70 Ice 0.05 to .20 Snow 0.30 to .60 Source: Lynn Fricke, Northwestern Univ.
  • 301. 301 Decision Sight DistanceDecision Sight Distance • SSD are sufficient to allow reasonably competent and alert drivers to come to a hurried stop under ordinary circumstances • May be inadequate when drivers must make complex or instantaneous decisions, when information is difficult to perceive or when unexpected or unusual maneuvers are required • Equations in book, use tables
  • 302. 302 Decision Sight DistanceDecision Sight Distance • When situation is unexpected or driver must make unusual maneuvers or under difficult-to-perceive situations • Requires higher P/R time • Depends on type of maneuver made and roadway setting (urban vs. rural) • Use table 3.5 from Text, page 75
  • 303. 303 Decision (controlled stop, speed/path/route change) – DSD (Table 3-3) Source: A Policy on Geometric Design of Highways and Streets (The Green Book). Washington, DC. American Association of State Highway and Transportation Officials, 2001 4th Ed.
  • 304. 304 Passing Sight DistancePassing Sight Distance Assumptions (conservative?): 1. Vehicle being passed travels at uniform speed 2. Speed of passing vehicle is reduced behind passed vehicle as it reaches passing section 3. Time elapses as driver reaches decision to pass 4. Passing vehicle accelerates during the passing maneuver and velocity of the passing vehicle is 10 mph greater than that of the passed vehicle 5. Enough distance is allowed between passing and oncoming vehicle when the passing vehicle returns to its lane
  • 305. 305 Source: A Policy on Geometric Design of Highways and Streets (The Green Book). Washington, DC. American Association of State Highway and Transportation Officials, 2001 4th Ed.
  • 306. 306 Passing Sight DistancePassing Sight Distance Dpassing = d1 + d2 + d3 + d4 d1 = distance traveled during P/R time to point where vehicle just enters the left lane d1 = 1.47t1(u – m + at1) 2 where t1 = time for initial maneuver (sec) u = average speed of passing vehicle (mph) a = acceleration (mph/s) m = difference between speeds of passing and passed vehicle
  • 307. 307 Passing Sight DistancePassing Sight Distance Dpassing = d1 + d2 + d3 + d4 d2 = distance traveled by vehicle while in left lane d2 = 1.47ut2 where: u = speed of passing vehicle (mph) t2 = time spent passing in left lane (sec)
  • 308. 308 Passing Sight DistancePassing Sight Distance Dpassing = d1 + d2 + d3 + d4 d3 = clearance distance varies from 110 to 300 feet d4 = distance traveled by opposing vehicle during passing maneuver d4 usually taken as 2/3 d2
  • 309. 309 Important Sight DistancesImportant Sight Distances (cont.)(cont.) 4. Intersection (turning/crossing) 5. Crossing RR 1. Stop, proceed, proceed from stop
  • 311. 311 What are the key variables?
  • 312. 312 Key issues in safe crossingKey issues in safe crossing Speeds D Distance from front of vehicle to driver’s eye Dt Distance from rail to front of vehicle Vv Assumptions about PR time and braking distance W Width of crossing D Distance from end of vehicle after crossing L Length of vehicle Acceleration capability of road vehicle Offset of obstruction from the road and the rail line
  • 313. 313 HomeworkHomework Go to the example on slide 24. Calculate the vehicle speed if the roadway is gravel. Next calculate the vehicle speed on the paved roadway, but with snow and ice on the road (f = 0.30). Show your work and discuss how much a driver should reduce his/her speed for ice and snow on the paved road.