1. COMP23420: Software Engineering
Semester 2, AY 2011-2012
Lecture 2: Introducing Driver
Rostering Process
Dr L. Zhao
liping.zhao@manchester.ac.uk
School of Computer Science
Subject Website: http://moodle.cs.man.ac.uk/

2. Teaching Team and Contact
• Lecturers:
– Dr John Sargeant (johns@cs.man.ac.uk)
– Dr Liping Zhao (lzhao@cs.man.ac.uk)
• Teaching Assistants:
– Erol-Valeriu Chioasca (chioasca@cs.man.ac.uk)
– James Naish (james.naish@postgrad.manchester.ac.uk)
• Demonstrators
Copyright © 2012, L Zhao slide 2

3. Lecture Aim
• Introduce public transportation planning processes
• Introduce driver scheduling and rostering
• Providing a basic understanding of driver scheduling and
rostering through simulation
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4. What is Driver Rostering?
• To answer this question, you need to understand the
four public transportation planning processes
– Timetabling: sets the level of service to be provided in
terms of when and where vehicle journeys are to be made.
Output: bus timetable.
– Vehicle or bus scheduling: allocates these journeys to
vehicles. Output: bus schedule.
– Driver scheduling: assigns driver duties to cover the
vehicle work. Output: driver schedule.
– Rostering: combines driver duties with rest days to form
work plans for drivers. Output: driver roster.
Timetabling Bus Scheduling Driver Scheduling Rostering
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5. Driver Scheduling and Rostering
• Driver scheduling deals with the notional rather than
actual driver assignment.
• The actual driver assignment happens in the rostering
process when driver duties are combined with the rest
days to form work plans for drivers.
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6. Driver Scheduling Problem
• The problem of bus driver scheduling is defined as
follows:
“Given a bus schedule that sets out the precise work to be
undertaken by each of the buses in a fleet during the course of
a day, it is necessary to form and allocate drivers’ duties so
that every bus has a driver at all times.” – Anthony Wren
• The main objective of driver scheduling is to minimize the
number of duties required and the total cost of duties.
• In line with this objective, a good driver schedule is the one
that contains a minimum number of duties.
• Driver scheduling is constrained by a complex set of rules and
constraints:
– The bus schedule, which defines the bus work for driver duties,
– The labour rules, which specify a company’s policy and union
agreements for driver duties.
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7. Solving Driver Scheduling Problems by Computer
• The driver scheduling problem is computationally
intractable (NP hard), as there are numerous ways to
cover the same piece of bus work
• Due to the combinatorial nature of scheduling constraints
and variables
• First driver scheduling software systems were developed
in 1960 by Professor Anthony Wren of University of
Leeds
• Those early systems solved driver scheduling problems
by heuristics, which simulate the way by which an expert
scheduler solves the scheduling problem.
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8. Driver Scheduling Approaches
• Solving the problem through optimisation
• Algorithms
– Heuristics (human problem solving methods)
– Meta-heuristics
– Genetic algorithms
– Human computer interaction – simulate manual scheduling
• Mathematical programming methods
– Integer Linear Programming (ILP)
– Set covering and partitioning methods
– Column generation
– Constraint programming
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9. IBMS Project
• You will be given a bus timetable and a bus schedule.
• Your task is to produce a simple driver schedule and a
driver roster.
• Because the problem is simple, you can combine driver
scheduling process with the roster process – I will give
you some examples soon.
• You will be given a set of simple driver scheduling
constraints, called “rostering rules”.
• The project is sufficiently challenging for a second year
UG SE course.
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10. IBMS Rostering Rules
• (they are available at the course unit’s Moodle site)
• A roster is generated for each week based upon the timetable for
that week.
• The maximum driving time for any driver in any one day is 10
hours.
• There can be no more than 50 hours driven by any one driver in
any one week.
• A driver can drive for a maximum of 5 hours at any one time and
must have a break of at least one hour. Breaks can only be taken at
the bus depot.
• A driver shift consists of one period of up to 5 hours driving time, or
two such periods with a 1 hour break between them.
• Time spent with the bus whilst not actually moving counts as
driving time for the driver (that is, while responsible for the bus).
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11. IBMS Rostering Rules (cont.)
• There is a sufficiency of fuelled buses available for the roster.
• If a bus is available, it is available for the whole day.
• A driver may specify up to two resting days for each week in which
they will not be available for work. (We assume not all drivers will
choose the same two days.)
• Drivers can normally take 25 days of holidays a year – this is in
addition to the two resting days a week they specified.
• For any weekdays, the maximum number of drivers who can
request the same holidays is 10 and the request is approved by the
company management in the order of first-come-first –served.
During Sundays and public holidays when fewer buses are in
operation then it is possible for more than 10 drivers to request the
holidays for the same period. This information should be available
from the database provided.
• If a driver requests holidays, he or she should specify the intended
starting date and the finishing date.
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12. The Criteria for a Good Roster
• Rostering should maximise the amount of time a driver
actually drives during a shift whilst not violate rules for
driver breaks.
• The number of drivers used in a roster is minimised.
• The number of days worked per week per driver is
minimised.
• The allocation of hours in a week to drivers is fair.
• The use of buses should be balanced to give each bus a
roughly equal workload in any one roster.
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13. Rostering Simulation
• The PowerPoint presentation that follows provides an insight into the
driver scheduling and rostering processes
– It is NOT intended to tell you what specific rostering algorithm to use,
but to show how you might develop an algorithm!
• A weekly timetable for a single route is composed, building up the
roster for a single driver on a single route subject to some naive
example constraints and using 4 hour “duty blocks”
– You have been given a set of constraints that your rostering algorithm
should satisfy
• The implications of the simple rostering strategy are then examined
in terms of the timetable for a whole week for a single route (no.
66)
– The roster is incomplete and requires further drivers
• Alternative rostering strategies are then examined, e.g. allocating
multiple drivers to a route, allocating pairs of drivers in alternate 2
hour “blocks”
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14. 4 Hour
Driver Day Route Times Route Times Route No. 66
Block Monday
Fred 66 06.00 77 12.00
Smith 10.00 13.30 Stop 4
1 1 1 1 1 1 .5 1 .5
Tuesday Monday
Hr Hr Hr Hr Hr HrHrHrHr 66 06.00 77 12.00 +45 mins
Tuesday10.00 13.30 Stop 3
… Stop 5 +55mins +25mins
Wednesday
Saturday 66 06.00 77 12.00
Thursday
10.00 13.30
Friday Stop 6 +75mins +20mins Stop 2
Lunch hour between 10.00-12.00
No Breaks Saturday
Stop 7 +90 mins
Sid Monday 66 10.00
Lunch
Rest Breaks
Driving Bus
Jones 14.00
Work Pattern:
… Work Pattern: Stop 8 +110 mins
Driver = Fred Smith +10mins Stop 1
Friday Driver = Joe Jones
66 10.00
14.00
Driver Day
Route 66 Route Times O’Clock
4 Hour Terminus Stockport
Joe
Fred Monday 10.00
66 06.00 Block Bus Station
Rostered for Mon-Sat 06.00-10.00
Jones
Smith 14.00
10.00
Tuesday Mon-Fri 10.00-14.00
06.00
07.00
08.00
09.00
10.00
11.00
12.00
13.00
14.00
15.00
16.00
17.00
18.00
19.00
20.00
21.00
22.00
66 06.00
10.00
Route … 77
Saturday 66 06.00
Friday 10.00
Rostered for Mon-Sat 12.00-13.30
10.00
14.00

15. Route 66: Weekly (1)
06.00
07.00
08.00
09.00
10.00
11.00
12.00
13.00
14.00
15.00
16.00
17.00
18.00
19.00
20.00
21.00
22.00
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
Driver 1 What to do about ?
Driver 2 Re-roster with allocation block = 2 Hours?
Driver 3 Allocate as overtime to another driver
(who has requested overtime)?
Driver 4
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16. Route 66: Weekly(2)
06.00
07.00
08.00
09.00
10.00
11.00
12.00
13.00
14.00
15.00
16.00
17.00
18.00
19.00
20.00
21.00
22.00
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
Now, 8 drivers, still unrostered at certain times and days…
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17. Route 66: Weekly(3)
06.00
07.00
08.00
09.00
10.00
11.00
12.00
13.00
14.00
15.00
16.00
17.00
18.00
19.00
20.00
21.00
22.00
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday
2 drivers alternating for maximum of 6 hours driving each,
2 other drivers rostered for 5 days/week,
still unrostered at certain times
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18. What Next?
• These slides are available at the course unit Moodle
page.
• You can play with them to get a better idea.
• If you want to get real, read my following research
paper:
– L. Zhao, “A Heuristic Method for Analyzing Driver Scheduling
Problem,” IEEE Transactions on Systems, Man and Cybernetics—
Part A: Systems and Humans, vol. 36, no. 3, pp. 521-531, May
2006.
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