safety effects of flashing yellow arrow update february 2009
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
Presentation Overview
• Background
• North Carolina Sites
• North Carolina Crash Data Monitoring
• Summary
North Carolina Installations
• Installations by year
Planned Installations
• 50+ sites: Design complete / installation pending• 50+ sites: FYA approved / Design in progress
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
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
PRELIMINARYBefore and After Crash Summary
Number of Sites: 3
Average Before Period: 2.1 years
Average After Period: 0.5 years
Grouped Before After Reductions
Category 1: Permissive Only to FYA Protected-Permitted
PRELIMINARYBefore and After Crash Summary
Grouped Before After Reductions
Significant Increase
Category 2: Protected Only to FYA Protected-Permitted
Number of Sites: 7
Average Before Period: 3.0 years
Average After Period: 0.8 years
PRELIMINARYBefore and After Crash Summary
Category 3: “Doghouse” Protected-Permitted to FYA Protected-Permitted
PRELIMINARYBefore and After Crash Summary
Grouped Before After Reductions
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
• 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
Key Points / Summary
Contact Information
Brian G. Murphy, PE(919) [email protected]
Traffic Safety Unit Website: http://
www.ncdot.org/doh/preconstruct/traffic/TSU/default.html