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The Built Environment, Traffic Safety and Travel Choice

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Dr. Norman Garrick, of the University of Connecticut's Center for Transportation and Urban Planning, on street connectivity and public safety.

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The Built Environment, Traffic Safety and Travel Choice

  1. 2. Davis, CA 14 % of people ride to work
  2. 3. Davis, CA Road Fatality Rate: 1 per 100,000
  3. 4. Road Fatality Rate for All 157 California Cities Over 40,000 number per 100,000 population 0.0 17.3
  4. 5. Road Fatality Rate for All 157 California Cities Over 40,000 number per 100,000 population
  5. 6. Norman W. Garrick
  6. 8. Risk of Fatality (Fatalities as % of Injuries) California Cities of 40,000 to 120,000
  7. 10. Adapted from Stephen Marshall Pre-1950’s Post-1950’s Evolution of the Street Network
  8. 14. FHA Technical Bulletin No. 7 (1938) Planning Profitable Neighborhoods
  9. 15. <ul><li>According to the FHA the grid layout was </li></ul><ul><li>Monotonous </li></ul><ul><li>Had Little Character </li></ul><ul><li>Uneconomical </li></ul><ul><li>Posed Safety Concerns </li></ul>
  10. 16. Street network, safety and sustainability in 24 medium sized California cities Cities selected to represent a range of traffic safety level
  11. 18. <ul><li>Shape and Configuration </li></ul><ul><li>Network Scale </li></ul><ul><li>Network Connectivity </li></ul>
  12. 19. Citywide Street Network Neighborhood Street Network Linear Tree Grid Tributary Radial Grid Tree Adapted from Stephen Marshall, Streets & Patterns
  13. 20. 550 Intersections per Square Mile Network Scale
  14. 21. 110 Intersections per Square Mile Network Scale
  15. 22. 45 Intersections per Square Mile Network Scale
  16. 23. Link-to-Node Ratio = 1.61 Link-to-Node Ratio = 1.13 Link-to-Node Ratio = 1.16 Network Connectivity
  17. 24. <ul><li>Street Network Properties </li></ul><ul><li>Street Design Properties </li></ul><ul><ul><li>Average Total Number of Lanes </li></ul></ul><ul><ul><li>Average Outside Shoulder Width </li></ul></ul><ul><ul><li>Raised Median </li></ul></ul><ul><ul><li>Painted Median </li></ul></ul><ul><ul><li>On-Street Parking </li></ul></ul><ul><ul><li>Bike Lanes </li></ul></ul><ul><ul><li>Raised Curbs </li></ul></ul><ul><li>Travel and Activity Level </li></ul><ul><li>Distance from City Center </li></ul><ul><li>Income </li></ul><ul><li>Mix of Land Use </li></ul>Variables included in Our Safety and Travel Choice Models
  18. 25. Safety Analysis Based on Geo-coding 230,000 Accident Records in 24 California Cities
  19. 26. Safety and Travel Choice Analysis done for 1040 Census Block Groups 24 California Cities
  20. 27. Travel Choice Based on Census Data 1040 Census Block Groups, 24 California Cities
  21. 28. versus
  22. 29. versus Safety Risk of Severe Injury or Fatality Chance of being Severely Injured 30% Higher Chance of being Killed 50% Higher
  23. 30. Odds of Dying in a Road Accident based on Intersection Density 1 in 200 1 in 500
  24. 31. Percentage of People Walking, Biking or Taking Transit
  25. 32. Percentage of People Walking, Biking or Taking Transit Effect of Intersection Density for Cul-de-sac Network
  26. 33. Percentage of People Walking, Biking or Taking Transit Effect of Intersection Density for Gridded Network
  27. 34. Evolution of Network in California Cities
  28. 35. Norman W. Garrick 11 X 2 X
  29. 37. Norman W. Garrick Sustainability Gap USA Norway Daily Miles Traveled For every man, woman and child
  30. 41. 28,000 14,000 8,000
  31. 45. 15,000 11,000 14,000 11,000

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