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SPEED LIMITS

SPEED LIMITS. 2011 Statewide Traffic Engineers Meeting Jody Colvin. How Do I Pick?. Some want:. Others want:. While still others want:. What’s an Engineer to do?. 2003 MUTCD. Standard: After an engineering study has been made in accordance with established traffic engineering practices…

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SPEED LIMITS

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  1. SPEED LIMITS 2011 Statewide Traffic Engineers Meeting Jody Colvin

  2. How Do I Pick?

  3. Some want:

  4. Others want:

  5. While still others want:

  6. What’s an Engineer to do?

  7. 2003 MUTCD • Standard: After an engineering study has been made in accordance with established traffic engineering practices… • Guidance: When a speed limit is posted, it should be within 5 mph of the 85th percentile speed of free flowing traffic.

  8. 2009 MUTCD • Standard: Speed zones (other than statutory) shall only be established on the basis of an engineering study that has been performed in accordance with traffic engineering practices. The engineering study shall include an analysis of the current speed distribution of free flowing vehicles. • Guidance: When a speed limit is posted, it should be within 5 mph of the 85th percentile speed of free flowing traffic.

  9. 3 E’s • Engineering • Enforcement • Education

  10. Reasonable Speed Limits • Respect • Realistic • Enforceable • Safe

  11. UN Reasonable Speed Limits How many people must die! • Respect • Realistic • Enforceable • Safe The drunks are driving way too fast “Feelings” Protect my children! People speed thru here

  12. National • Engineering a reasonable speed limit at or near the 85th % • Enforcing at the 95th % • Educating the public with public information spots, newspaper ads, etc

  13. Engineering a Speed Limit • Data needed: • Speed data (50th%, 85th%, and 95th%) • Crash reports (not summary) • Roadway characteristics • Driveway density • Pedestrian and Bicycle information

  14. Speed Data • 100 free flow vehicles • Non-peak time • Not near curves or intersections • Radar, loops, video…

  15. Crashes=Posted Speed? • How is safety related to the posted speed? • Have you seen a crash report where it stated that the vehicle was going the speed limit which was too fast and so they crashed? • What is more important a speed limit that is enforceable, safer, and realistic or a slower speed to make people “feel” better? • What about speed differential?

  16. Crash Reports • Perceived Danger or Real • Determine crash patterns • Site visits with State Police and local law enforcement • Develop solutions

  17. High 85th % • Figure out why are people going this speed • Develop Traffic Calming • Restudy area to determine if the 85th% decreased

  18. High 85th % • Figure out why are people going this speed • Develop Traffic Calming • Restudy area to determine if the 85th% decreased realistic enforceable

  19. DO NOT Just Lower Speed Limit • Enforcement can only do so much! • If speeding then no respect for sign • So try: • “Your Speed Is” signs

  20. DO NOT Just Lower Speed Limit • or Traffic Calming

  21. DO NOT Just Lower Speed Limit • Traffic Calming

  22. DOTD Proposed Policy • Require speed limits to be set at the nearest 5mph interval of the 85th% speed • Committee to review the proposed speeds to ensure a consistent setting of speed limits for similar conditions • Working with State Police on developing realistic speed limits that are enforceable • Public Information to do press releases on speed limit changes • Reviewing speed limits every 5 years

  23. Speed Study • Retainer contract • Speed data collection • 24 hour • 100 vehicles • Roadside inventory • Number of driveways • Pedestrians • Commercial vs Residential • Shoulders, width….. • Database

  24. SUMMARY • Need to do better job at educating • Need to set more consistent speed limits • Need to review speed limits

  25. QUESTIONS? Thanks Jody Colvin 225-242-4635 Jody.Colvin@la.gov

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