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Making Connectivity A Part of Your Smart Growth. APA Washington October 6, 2010. 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 - PowerPoint PPT Presentation
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Making Connectivity A Part of Your Smart Growth
APA Washington
October 6, 2010
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
Marshall and Garrick California Cities Comparison
Safer Cities
Less Safe Cities
Difference %
Year of Incorporation Average
1895 1932
Population 2000 average
65,719 59,845 -8.0
Fatal crashes not on highwaysAverage per city per year per 100,000 population
3.1 10.1 273.9
Real Intersection Density City average per square mile (not including dead ends)
106.2 62.7 -41.0
Local Road density City average centerline miles per square mile
15.1 11.2 -25.8
Block Size City average in acres
18.2 34.5 89.6
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 BikingWesley Marshall and Norman Garrick, November 2009
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
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
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
ViaCity RDI Applied to Olympia
Olympia Test:
• Baseline street centerlines• Add existing trails• Add planned connectors• See RDI improve• Sub area demonstrations
ViaCity RDI Applied to Olympia
1
2 3
4Connectors
Shared-Use Paths
Subarea Connectivity Analysis
Olympia Citywide RDI
Pedestrian Connectors & Pathways
Connectors
Shared-Use Paths
Area 1: Baseline Connectivity
Area 1: Plan Impact
Connectors
Area 1: RDI Statistics
Connectors
Area 2 : Baseline Connectivity
Area 2 : Plan Impact
Connectors
Area 2 : RDI Statistics
Connectors
Area 3 : Baseline Connectivity
Area 3 : Plan Impact
Connectors
Area 3 : RDI Statistics
Connectors
Area 4 : Baseline Connectivity
Area 4 : Plan Impact
Connectors Shared-Use Paths
Area 4 : RDI Statistics
Connectors Shared-Use Paths
Subarea Improved Connectivity
Connectors
Shared-Use Paths
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