Loading...
09.09.24 TAB Agenda 7.a.i Signal PracticesSignal Timing Practices Update Transportation Advisory Board September 9, 2024 Transportation & Mobility | Agenda Transportation & Mobility Signal Timing Practices •Signal Practices Overview •Vision Zero Context •Implementation Success •Existing Signal System Context •Scope of Work Considerations •Next Steps Signal Practices Overview Signal Timing Practices Maintenance Construction Planning & Warrants Design Operations VZAP Focus Leading Pedestrian Intervals Signal Practices Overview Transit Signal PrioritySignal Modes & Coordination Operations Exclusive Pedestrian Phases Left-Turn Phasing Special Event Timing Standard Timing Settings Emergency Operations Right-Turn on Red Signal Practices Overview •Left-Turn Phasing o Permitted Only o Protected Only o Protected-Permitted •Evaluation Criteria o Physical/Geometric o Volume o Speed o Crashes o Delay o Current left turn phasing Signal Practices Overview •Right-Turn on Red •Evaluation Criteria o Sight distance o Multimodal volumes o Signal phasing o Crash history o Intersection geometry Signal Practices Overview •Leading Pedestrian Intervals •Evaluation Criteria o Responsive o Crash history o Proactive o Exposure/risk o Opportunistic o Impact to operations Responsive Is correctable crash frequency ≥3 total in the past 3 years? Proactive Opportunistic Min. Ped Vol ≥ 50/hr AND Min. Right Turn Vol ≥ 100/hr AND Min. Prob 1st Veh. Is a Right- Turn ≥ 50% Can a min. 3 sec LPI be accommodated w/ minimal impact to signal operations? Vision Zero Context •For the period from 2020-2023, there have been an average of 48 severe crashes per year. •37% of severe crashes occur at signalized intersections. 37% 63% Location of Severe Crashes Traffic Signal Other Vision Zero Context 8.3 5 1.5 0.8 0.8 0.5 0.5 0.3 0.3 Type & Number of Severe Crashes Per Year at Signals Approach Turn Red-Light Running Crossing Against the Signal Reckless Driving/Speeding Rear-End Right-Turn Bypass Right Turn on Red Right-Turn Hook Sideswipe •Nine main crash types have led to severe crashes at signals. •Approach turn and red-light running are the types that result in most severe crashes. Vision Zero Context •Left turn related crashes at signals currently make up about 17% of all annual severe crashes. 20% 17% 63% Location of Severe Crashes Traffic Signal Left Turn at Signal Other Implementation Success •Before/after analysis of left turn phasing changes shows a 68% reduction in approach turn crashes. 0 20 40 60 80 100 120 140 160 Flashing Yellow Arrow Left Turn Phasing Change LPI RTOR Restriction Number of Changes Installed Since 2018 Existing Signal System Context Type of Left Turn Phasing # of Approaches % of Approaches Permitted Only 164 33% Shared Lane – No Left Turn Phase 76 15% Protected-Permitted – FYA -TOD 73 15% Protected Only – TOD 48 10% Permitted Only – FYA 43 9% No Conflicting Pedestrian Phase 41 8% Protected Only – 24/7 35 7% Protected-Permitted – TOD 9 2% Protected-Permitted – 24/7 2 0% Ped Protect – TOD 2 0% Ped Protect – 24/7 1 0% Total 494 100% Existing Signal System Context Permitted Only Left Turn Phasing •Canyon Blvd/15th St – EBLT Existing Signal System Context Permitted Only Left Turn Phasing w/ Flashing Yellow Arrow •Arapahoe Ave/Cherryvale Rd – WBLT Existing Signal System Context Pedestrian Protected Left Turn Phasing •30th St/Walnut St – EBLT Existing Signal System Context No Conflicting Pedestrian Phase •Colorado Ave/Foothills Pkwy – EBLT Existing Signal System Context Shared Lane – No Left Turn Lane •30th St/Glenwood Dr – NBLT Scope Considerations •New practices •Evaluation criteria •Tradeoffs •Technology •Geometric or other changes •Prioritization methodology Scope Considerations •Deliverables Takeaways •Good crash data is essential to understanding underlying causes •Engineering solutions can make the system more foolproof and forgiving •Many solutions can be lower cost (striping or signal phasing) •Many solutions can be win/win (improved safety with limited operational impacts) •Continued strategic and targeted focus on left turn crashes can have a significant positive effect on achieving Vision Zero Next Steps •City Council – Matters from City Manager – October 17 •Consultant selection process – Q4 2024 •Finalize scope of work, schedule, budget – Q4 2024 •Begin work – Q1 2025 •Additional TAB/Council check-ins – Q2 2025 •Anticipated completion of practices update – Q3 2025 •Begin implementation of programming changes across High Risk Network – Q4 2025