Pedestrian Timing Strategies at Large Signalized Intersections

Transcription

1 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

2 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

3 PED. CROSSING AT TRAFFIC SIGNALS Pedestrian crossing concurrent with parallel vehicle movement Sufficient time must be provided to allow ped safely crossing Green >= WALK + FDW Conflict with turning vehicles

4 SAFETY VS. EFFICIENCY Safety Long WALK + FDW Ped. Protected Phase (Separate Ped and Vehicles) Efficiency Long Green (Minor St.) Less Green (Main St.) Increased Lost Time Less Capacity Safety Efficiency

5 LARGE INTERSECTIONS Minor St Nevada Fall Transportation Conference

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

7 TWO-STAGE PEDESTRIAN CROSSING

8 TWO-STAGE PEDESTRIAN CROSSING

9 TWO-STAGE PEDESTRIAN CROSSING

10 TWO-STAGE PEDESTRIAN CROSSING

11 TWO-STAGE PEDESTRIAN CROSSING

12 TWO-STAGE PEDESTRIAN CROSSING

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

14 SPLIT PHASING Sequentially providing green and serving the two opposite approaches

15 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

16 PROTECTED LEFT TURN ** Two Pedestrian Splits N Time

17 SB Vehicles Need 30 Green per Cycle Total Vehicle Need = 45 Total Ped Need = 70 Peds Need 5 Walk + 30 FDW NB Vehicles Need 15 Green

18 PERMITTED LEFT TURN Total Vehicle Need = 45 Total Ped Need = 35 ** One Pedestrian Split N Time

19 PROTECTED/PERMITTED LEFT TURN ** One Pedestrian Split Total Vehicle Need = 45 Total Ped Need = 35 N a) With Conflicting Pedestrian Crossings on Both Sides b) With Conflicting Pedestrian Crossings on East Side

20 PROTECTED/PERMITTED LEFT TURN ** One Pedestrian Split N c) With Conflicting Pedestrian Crossings on West Side d) W ithout Conflicting Pedestrian Crossings

21 PROTECTED/PERMITTED LEFT TURN Φ1 Φ5 Φ6 Φ2 Φ10* Φ3 Φ7 Φ9* Ring 1 Ring 2 N Φ4 (Ped Right) Ring 3 Φ8 (Ped Left) Ring 4 * Note: It may require to output φ9 and φ10 load switches to φ8 and φ4, respectively e) Controller Phase and Ring Structures

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23 Ph.4 VD Back Panel Wiring Ph.8 VD Ph.4 PD Ph.8 PD Ph.4 HLD Ph.8 HLD Ph.4 OM T Ph.8 OM T Ph.4 PO Ph.8 PO Ph.4 CHK Ph.8 CHK Ph.4 NXT Ph.4 ON Ph.8 NXT Ph.8 ON LEGEND VD = Vehicle Detector PD = Ped Detector HLD = Phase Hold OMT = Phase Omit PO = Ped Omit CHK = Check Calls NXT = Next Phase ON =Phase On Ph.3 VD Ph.3 PD Ph.3 HLD Ph.3 OM T Ph.3 PO Ph.3 CHK Ph.3 NXT Ph.3 ON Ph.7 VD Ph.7 PD Ph.7 HLD Ph.7 OM T Ph.7 PO Ph.7 CHK Ph.7 NXT Ph.7 ON D iode device

24 NO PED ON WEST LAG CROSSWALK (NB GREEN ARROW) NB Approach

25 WITH WEST LAG PED (NB GREEN BALL) NB Approach

26 STATIC OR DYNAMIC SIGN

27 LAS VEGAS PROTECTED/PERMITTED

28 TWO-STAGE CROSSING * Reduced Pedestrian Splits Time

29 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 , 2001.

30 EXCLUSIVE VS. PROTECTED LT MODEL 1500 Time Savings, sec/hr γ =0.2 γ = γ = γ =1.5 γ =2.0 Exclusive Best Concurrent Best Model Elements: Ped Volume Cycle Length γ = (T a + T b )/t p Ped Time (t p ) Data for the Figure: Cycle = 100 sec t p = 35 sec Pedestrian Volume, ped/hr

31 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 ICTTS 2000, ASCE, Beijing, China.

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

33 Tian s website at UNR: