Pedestrian Timing Strategies at Large Signalized Intersections

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Pedestrian Timing Strategies at Large Signalized
Intersections

• Zong Tian, Ph.D., P.E.
• Department of Civil Environmental Engineering
• University of Nevada Reno
• Reno, NV 89557

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OVERVIEW

• Safety Efficiency Issue
• Impact of pedestrian timing on signal operations
• Pedestrian Timing Strategies
• Two-stage crossing
• Split phasing
• Exclusive ped phase
• Summary and Conclusions

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PED. CROSSING AT TRAFFIC SIGNALS

• Pedestrian crossing concurrent with parallel
  vehicle movement
• Sufficient time must be provided to allow ped
  safely crossing
• Green gt WALK FDW
• Conflict with turning vehicles

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SAFETY VS. EFFICIENCY

• Safety Efficiency
• Long WALK FDW Long Green (Minor St.)
  Less Green (Main St.)
• Ped. Protected Phase Increased Lost
  Time(Separate Ped and Vehicles) Less Capacity

Efficiency
Safety
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LARGE INTERSECTIONS
Minor St.
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ISSUES

• Low vehicle demand but long ped time
• Two-stage crossing longer ped delay
• Significant impact under split phasing
• Coordination issue (ped time treatments)

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TWO-STAGE PEDESTRIAN CROSSING
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TWO-STAGE PEDESTRIAN CROSSING
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TWO-STAGE PEDESTRIAN CROSSING
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TWO-STAGE PEDESTRIAN CROSSING
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TWO-STAGE PEDESTRIAN CROSSING
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TWO-STAGE PEDESTRIAN CROSSING
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PEDESTRIAN TIMING SCENARIOS

• Pedestrian Delay Models at Signalized
  Intersections Considering Signal Phasing and
  Pedestrian Treatment Alternatives (09-2537) by
  Wang et al.
• One-stage crossing
• Current two-stage without overlaps
• Two-stage with overlaps

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SPLIT PHASING

• Sequentially providing green and serving the two
  opposite approaches

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PED. TREATMENT UNDER SPLIT PHASING

• Left-turn green arrow
• (Protected LT)
• No left-turn arrow
• (Permitted LT)
• Dynamic display
• (Protected/Permitted)

Acknowledgement Some of the following pictures
were borrowed from a presentation by Scott
Wainwright of FHWA
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PROTECTED LEFT TURN
N
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Total Vehicle Need 45 Total Ped Need 70
SB Vehicles Need 30 Green per Cycle
Peds Need 5 Walk 30 FDW
NB Vehicles Need 15 Green
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PERMITTED LEFT TURN
Total Vehicle Need 45 Total Ped Need 35
One Pedestrian Split
N
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PROTECTED/PERMITTED LEFT TURN
Total Vehicle Need 45 Total Ped Need 35
One Pedestrian Split
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PROTECTED/PERMITTED LEFT TURN
One Pedestrian Split
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PROTECTED/PERMITTED LEFT TURN
N
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(No Transcript)
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Back Panel Wiring
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NO PED ON WEST LAG CROSSWALK(NB GREEN ARROW)
West Lag
NB Approach
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WITH WEST LAG PED (NB GREEN BALL)
NB Approach
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STATIC OR DYNAMIC SIGN
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LAS VEGAS PROTECTED/PERMITTED
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TWO-STAGE CROSSING
Reduced Pedestrian Splits
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EXCLUSIVE/SCRAMBLE
Tian, Z., Urbanik, T., Engelbrecht, R., and
Balke, K. Pedestrian Timing Alternatives and
Impacts on Coordinated Signal Systems Under Split
Phasing Operations Transportation Research
Record 1748, pp. 46-54, 2001.
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EXCLUSIVE VS. PROTECTED LT MODEL
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COORDINATED SIGNALS

• Two timing alternatives to handle pedestrians
• Ped timing accommodation
• Longer cycle
• No ped timing accommodation
• Out of synch/Transition

Tian et al. (2000) . Pedestrian Timing
Treatment on Coordinated Signal Systems,
Proceedings of ICTTS2000, ASCE, Beijing, China.
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SUMMARY AND CONCLUSIONS

• Efficiency Safety
• Two-stage crossing strategies
• Split phasing
• Exclusive/scramble phase
• Coordinated signals (to be continued)

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Tians website at UNR http//unr.edu/homepage/z
ongt