Street Networks: Traffic Safety, Travel Mode Choice and Emergency Services

Davis, CA 14 % of people ride to work

Davis, CA Road Fatality Rate: 1 per 100,000

Road Fatality Rate for All 157 California Cities Over 40,000 number per 100,000 population 0.0 17.3

Road Fatality Rate for All 157 California Cities Over 40,000 number per 100,000 population

Risk of Fatality (Fatalities as % of Injuries) California Cities of 40,000 to 120,000

Adapted from Stephen Marshall Pre-1950’s Post-1950’s Evolution of the Street Network

FHA Technical Bulletin No. 7 (1938) Planning Profitable Neighborhoods

According to the FHA the grid layout was
Monotonous
Had Little Character
Uneconomical
Posed Safety Concerns

Street network, safety and sustainability in 24 medium sized California cities Cities selected to represent a range of traffic safety level

Shape and Configuration
Network Scale
Network Connectivity

Citywide Street Network Neighborhood Street Network Linear Tree Grid Tributary Radial Grid Tree Adapted from Stephen Marshall, Streets & Patterns

550 Intersections per Square Mile Network Scale

Link-to-Node Ratio = 1.61 Link-to-Node Ratio = 1.13 Link-to-Node Ratio = 1.16 Network Connectivity

Street Network Properties
Street Design Properties
Average Total Number of Lanes
Average Outside Shoulder Width
Raised Median
Painted Median
On-Street Parking
Bike Lanes
Raised Curbs
Travel and Activity Level
Distance from City Center
Income
Mix of Land Use
Variables included in Our Safety and Travel Choice Models

Safety Analysis Based on Geo-coding 230,000 Accident Records in 24 California Cities

Safety and Travel Choice Analysis done for 1040 Census Block Groups 24 California Cities

Travel Choice Based on Census Data 1040 Census Block Groups, 24 California Cities

versus

versus Safety Risk of Severe Injury or Fatality Chance of being Severely Injured 30% Higher Chance of being Killed 50% Higher

Odds of Dying in a Road Accident based on Intersection Density 1 in 200 1 in 500

Percentage of People Walking, Biking or Taking Transit

Percentage of People Walking, Biking or Taking Transit Effect of Intersection Density for Cul-de-sac Network

Percentage of People Walking, Biking or Taking Transit Effect of Intersection Density for Gridded Network

Thanks to US EPA and CNU

28,000 14,000 8,000

15,000 11,000 14,000 11,000

8,346 10,524 12,831 8,600 2,461 28,820 7,518 6,774

16,186 10,364 13,154 24,283 5,898 15,547 17,107

Davis: Response Time 14.9 mph 14.2 mph 12.7 mph

Downtown Hartford 1960 to 2000 Parking

City of Hartford 1960 to 2000 Population and Employment

Evolution of Network in California Cities

Norman W. Garrick

Norman W. Garrick 11 X 2 X

Norman W. Garrick Sustainability Gap USA Norway Daily Miles Traveled For every man, woman and child

Working on Detroit

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Street Networks: Traffic Safety, Travel Mode Choice and Emergency Services

by Congress for the New Urbanism on Nov 12, 2009

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Street Networks: Traffic Safety, Travel Mode Choice and Emergency Services — Presentation Transcript