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Safety Effects of Flashing Yellow Arrow Update February 2009

Safety Effects of Flashing Yellow Arrow Update February 2009. Presentation Overview. Background North Carolina Sites North Carolina Crash Data Monitoring Summary. North Carolina Installations. Installations by year. North Carolina Installations. Installations by year.

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Safety Effects of Flashing Yellow Arrow Update February 2009

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  1. Safety Effects of Flashing Yellow ArrowUpdate February 2009

  2. Presentation Overview • Background • North Carolina Sites • North Carolina Crash Data Monitoring • Summary

  3. North Carolina Installations • Installations by year

  4. North Carolina Installations Installations by year Planned Installations • 50+ sites: Design complete / installation pending • 50+ sites: FYA approved / Design in progress

  5. North Carolina Crash Data Monitoring • FHWA requirement that these sites are monitored • All sites monitored on a yearly basis (NEW!) • Previously monitored quarterly • Due to number of sites now online, became inefficient to monitor quarterly • Some sites will be monitored more frequently as requested • Currently monitoring 43 sites

  6. Evaluation Challenges • Relatively new device • Few sites • Little ‘after’ data • Other changes made to signal at time of FYA installation • Timing changes, other signal head upgrades, turn lanes, new developments, etc… • Difficult to single out effect of FYA • Naïve before and after

  7. Grouped Before and After Data

  8. PRELIMINARYBefore and After Crash Summary Category 1: Permissive Only to FYA Protected-Permitted

  9. PRELIMINARYBefore and After Crash Summary Category 1: Permissive Only to FYA Protected-Permitted Number of Sites: 3 Average Before Period: 2.1 years Average After Period: 0.5 years Grouped Before After Reductions

  10. PRELIMINARYBefore and After Crash Summary Category 2: Protected Only to FYA Protected-Permitted

  11. PRELIMINARYBefore and After Crash Summary Category 2: Protected Only to FYA Protected-Permitted Number of Sites: 7 Average Before Period: 3.0 years Average After Period: 0.8 years Grouped Before After Reductions Significant Increase

  12. PRELIMINARYBefore and After Crash Summary Category 3: “Doghouse” Protected-Permitted to FYA Protected-Permitted

  13. PRELIMINARYBefore and After Crash Summary Category 3: “Doghouse” Protected-Permitted to FYA Protected-Permitted Number of Sites: 13 Average Before Period: 3.0 years Average After Period: 1.2 years Grouped Before After Reductions

  14. PRELIMINARYBefore and After Crash Summary All Categories Summarized

  15. Key Points / Summary • Still not enough data to make conclusive safety statements • Preliminary results seem promising • Likely will not see large crash reductions • Large increase in crashes at sites that went from protected to FYA protected-permitted likely due to phasing change and not FYA itself • TSU will continue to monitor and provide feedback

  16. Contact Information Brian G. Murphy, PE (919) 773-2898 bgmurphy@dot.state.nc.us Traffic Safety Unit Website: http://www.ncdot.org/doh/preconstruct/traffic/TSU/default.html

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