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

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Norman Garrick compares street network design from pre-1950 and post-1950, factors that help determine the overall safety of safe pedestrian travel, and explains why it is so obvious that the pandemic of sprawl development is to blame for unsafe, poorly designed, disconnected neighborhoods. Studies prove that Street Network Design has an integral role in providing safe, pedestrian friendly,and highly accessible communities. We must re-think the suburban model in order to reform emergency response.

Published in: Business, Technology

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

  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. 7. Risk of Fatality (Fatalities as % of Injuries) California Cities of 40,000 to 120,000
  6. 9. Adapted from Stephen Marshall Pre-1950’s Post-1950’s Evolution of the Street Network
  7. 12. FHA Technical Bulletin No. 7 (1938) Planning Profitable Neighborhoods
  8. 13. <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>
  9. 14. Street network, safety and sustainability in 24 medium sized California cities Cities selected to represent a range of traffic safety level
  10. 16. <ul><li>Shape and Configuration </li></ul><ul><li>Network Scale </li></ul><ul><li>Network Connectivity </li></ul>
  11. 17. Citywide Street Network Neighborhood Street Network Linear Tree Grid Tributary Radial Grid Tree Adapted from Stephen Marshall, Streets & Patterns
  12. 18. 550 Intersections per Square Mile Network Scale
  13. 19. 110 Intersections per Square Mile Network Scale
  14. 20. 45 Intersections per Square Mile Network Scale
  15. 21. Link-to-Node Ratio = 1.61 Link-to-Node Ratio = 1.13 Link-to-Node Ratio = 1.16 Network Connectivity
  16. 22. <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
  17. 23. Safety Analysis Based on Geo-coding 230,000 Accident Records in 24 California Cities
  18. 24. Safety and Travel Choice Analysis done for 1040 Census Block Groups 24 California Cities
  19. 25. Travel Choice Based on Census Data 1040 Census Block Groups, 24 California Cities
  20. 26. versus
  21. 27. versus Safety Risk of Severe Injury or Fatality Chance of being Severely Injured 30% Higher Chance of being Killed 50% Higher
  22. 28. Odds of Dying in a Road Accident based on Intersection Density 1 in 200 1 in 500
  23. 29. Percentage of People Walking, Biking or Taking Transit
  24. 30. Percentage of People Walking, Biking or Taking Transit Effect of Intersection Density for Cul-de-sac Network
  25. 31. Percentage of People Walking, Biking or Taking Transit Effect of Intersection Density for Gridded Network
  26. 32. Thanks to US EPA and CNU
  27. 33. 28,000 14,000 8,000
  28. 34. 15,000 11,000 14,000 11,000
  29. 35. 8,346 10,524 12,831 8,600 2,461 28,820 7,518 6,774
  30. 36. 16,186 10,364 13,154 24,283 5,898 15,547 17,107
  31. 37. Davis: Response Time 14.9 mph 14.2 mph 12.7 mph
  32. 42. Downtown Hartford 1960 to 2000 Parking
  33. 43. City of Hartford 1960 to 2000 Population and Employment
  34. 44. Evolution of Network in California Cities
  35. 45. Norman W. Garrick
  36. 46. Norman W. Garrick 11 X 2 X
  37. 48. Norman W. Garrick Sustainability Gap USA Norway Daily Miles Traveled For every man, woman and child
  38. 50. Working on Detroit

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