2. Why is Connectivity Important? Street network characteristics influence safety 24 California cities: safer and less safe Safer cities have reduced rates of severe and fatal crashes Safer cities have greater street and intersection density per sq mile Underlying factor may be lower vehicle speeds Source: Street network types and road safety: A study of 24 California cities Wesley Marshall and Norman Garrick, April 2010
4. Why Connectivity is Important Street network patterns influence mode choice Street network patterns: connectivity and density Connected dense street networks have higher walk, bike and transit mode-share Intersection density associated with greatest increases rates of walking and biking Model indicated: Increased intersections from 81 to 324 per sq mile would lead Walk/Bike combined mode share increases from 3.2% to 7.8% Source: The Effect of Street Network Design on Walking and Biking Wesley Marshall and Norman Garrick, November 2009
5. Why Connectivity is Important Associated with less driving CMHC study of Seattle neighborhoods: Fused grid increases walking trips by 11.3% A 10% increase in network density for pedestrians can be associated with 23% decrease in local vehicle miles travelled Sources: Canada Mortgage and Housing Corporation
6. Olympia’s Policies Where no street connection, build connector paths Block sizing good, 1800 feet max Street connections = moderate success Need to make case; data and analysis will help 100 non-motorized connectors inventoried Need to formalize existing connectors
7. ViaCity RDI Applied to Olympia Via City Route Directness Index (RDI) Measurement tool Transpo Group tests on Olympia RDI = tax parcel to all other parcels in specific radius Good RDI is 100, “as-the-crow-flies” direct Enhance network = RDI improves Case for street connections and connector path construction
8. ViaCity RDI Applied to Olympia Olympia Test: Baseline street centerlines Add existing trails Add planned connectors See RDI improve Sub area demonstrations
9. ViaCity RDI Applied to Olympia Subarea Connectivity Analysis Connectors 1 4 Shared-Use Paths 2 3
Our comp plan has strong policy language about the value of connectivity We believe connected streets work better for all modesAlways been in our interest to have a well connected system Just completed a TMS and Connectivity emerged as a major policy area needing enhancement
24Calif cities Similar in population - within 9% of each otherand within 5% of each other in VMTStudy looked at 130,000 crashes over 9 years Grouped in to safe and less safe based on crashes: safer cities had lower rates of sever and fatal crashesLooked at the street network characteristics and found safer cities had greater intersection density per sq mile, and greater street density as measured by centerline miles per sq mileUnderlying factor this study states is likely speeds, but the study did not explore road characteristics and exposureGraphics show roughly the type of well connected street grip, versus in the lower, a disconnected cul de sac from street network
Safer cities olderSimilar size around 60,000Safer cities have fewer fatal accidentsSafer cities have more intersections per sq mile, denser network of streets per sq mile, and smaller blocks in acres 18 acres per block for the safer cities
Another Marshall and Garrick study looked at mode choiceWe know Land Use and street featuresinfluence walking biking and transit useThis study shows that street network patterns have an affect on mode choice, specificallystreet connectivity and street density Study of same 24 California cities found that connected dense street networks have higher walk, bike and transit mode-shareThis was based on census journey to work data and the authors suggest there would likely be a greater influence of street network patterns on non-work trips, based on literature they reviewedOn example of the results of their model showed that:Increased intersections from 81 to 324 per sq mile would lead to Walk/Bike combined mode share increases from 3.2% to 7.8%
Canada Mortgage and Housing Corporation examined concept of fused gridFused Grid: connect streets, ends of cul de sacs, for peds and bikes, not carsCMHC study looked at several Seattle NeighborhoodsWhen comparing neighborhoods, the Fused Grid over a conventional street pattern increases home based walking trips by 11.3%And that a 10% increase in network density for pedestrians can be associated with 23% decrease in local vehicle miles travelled
Our development standards are typically 1800 foot block perimeter for residential zones This means for a perfectly square block with 450 foot block faces When we don’t get a street, a public bike and ped pathway is required. In last 20 years, about 10 rejected and about 8 connections have been made (byCouncil) All related to connecting to existing developmentReason don’t get streets: Neighborhood, Developers, object; topographic constraint Not as successful as we’d like. The cumulative impact on the transportation system when these connections are not madeSo we need data and more analysis to make the case of the value of these connections to policy makers and the public Have an inventory of over 100 non-motorized connectors Only 30 are on public property and only a few are formally developed.We don’t have a program to prioritize purchase and develop, maintain theseYet we want to make pathways a formal part of the transportation network. ViaCity, the software tool developed by the transpo group has potential to help demonstrate value of streets and pathways to the public and policy makers. We can demonstrate the impact of one connected street or a series of pathways in a neighborhood, or show the impact of a ideal fully connected network.
What happens when look at multi use trails and paths, essentially creating a fused grid ideaWould intent to go beyond that and connect streets
Connectors are short cut paths for walking and biking Over 100 have been inventoried in the city – some formal, some informal , some public some privateWould like these to become formal parts of the transportation system This tool quickly demonstrates the increased connectivity and gains to overall connectivity when the connectors are included in the route directness measure.
Blue parcels are associated with better connectivity in the downtown and older neighborhoods, The more red, those are associated with poor connectivity , typicallty in outlying areas and newer urban form or along highways
This is an overlay of the trails and connectors system
Northwest Olympia two schoolsOlder neighborhood and newer neighborhood to the east
Connectors betweencul de sacs added and form adjacent streets to the schools These are sometimes today just a dirt path or and path on private property that the City intends to make formal and public
The change can be quantified on the left X axis is RDI score: dark blue or a score of 100 is land that has the most direct connectivity Y axis is the percentage of land in this category of relative connectivity
Another example in southeast Olympia Neighborhood built in 50s mostly Major parks and watershed area in yellow
Again adding connectors increased access and
46% of the land area is now almost moderately good, better than fair connectivity
Southeast OlympiaOne of most disconnected neighborhood, built 70s to 90sLots of cul de sacs
Adding in public and private pathways creates a more fused grid
See about a 15% increase in the land that is fairly well connected (light blue) Made improvements but clearly more we could try to connect hereMore than the 100 known connectors should be pursued
Last example brings in the trail system in Northeast Olympia
The percentage of land that was poorly connected – either red or pink dropped about 15% About 75% of the land is fair to better in relative direct connectivity
A future step will be to add in street connectionsThis tool can also help us define areas needing new streets and pathways, those we aren’t aware of