Topic 7 Special Issues on Signal Coordination

1. Topic 7 Special Issues on Signal Coordination

2. Signal Timing with Large Systems • Difficult to obtain high bandwidth efficiency with a large number of signals in a system. • Only a small portion of the traffic goes through the entire arterial. • Seeking a system progression band with low efficiency may not be a good signal timing strategy.

3. System Partition Technique • Step 1. Divide the system into sub-systems (3~5 signals) • Divide at locations of capacity bottleneck and large spacing • Step 2. Obtain maximum bandwidth solution for each subsystem • Step 3. Form the peak direction progression band • Adjust offsets to achieve an one-direction bandwidth (peak) • Subsystem progression is retained for the other direction • Step 4. Fine tune the solution • Possible signal phasing change to improve the off-peak direction progression band; • Cross street with split phasing should be set at a sequence favoring progression of the left turns.

4. EXAMPLE

5. EXAMPLE

6. EXAMPLE

7. EXAMPLE

8. EXAMPLE

9. Speed Comparison – Arterial All Vehicles

10. Speed Comparison –Through Vehicles

11. Advantages • Maintain maximum progression for the peak direction. • The one directional progression band for the peak direction is the maximum that can be achieved from any optimization solutions. • Maintain maximum progression for the subsystems. • Subsystems have larger bandwidths on both directions. • More control and handle on queue and stops • Progression on the off-peak direction is partially maintained. But the users have complete control on where to stop vehicles and store queues.

12. Pedestrian Timing Treatment • Pedestrian crossing times are handled by concurrent vehicle through phases • Green time of vehicle phase must satisfy the WALK + FDW • Vehicle demands are low at minor streets, but pedestrian crossing times are high (wide street) • Split phasing presents more challenges • Two timing treatments • Vehicle minimum • Pedestrian minimum

13. Left Turn Leading Lead/Lag Pedestrian Timing Treatment Time

14. Pedestrian with Split Phasing

15. Optimal Cycle Length Signal Out-of-Coordination Timing Plan Reflects Actual Progression Easy Timing Plan Development Cycle Length Constraint Remain Coordination Progression According to Early Release Major Manual Adjustments Advantages/DisadvantagesVehicle Minimum Pedestrian Minimum

16. IDENTIFY EARLY RELEASE POINT

17. EFFECTIVE USE OF PHASING SCHEME 35 35 35 35

18. USE OF MAXIMUM RECALL Eastbound

19. Grid Network

20. Grid Network Φ2 Φ2 2 1 Φ4 Φ4 Φ2 Φ2 Φ4 Φ4 θ12 Time 0 3 4

21. Grid Network Φ2 Φ2 2 1 Φ4 Φ4 Φ2 Φ2 Φ4 Φ4 θ12+Φ2 θ12 Time 0 3 4 Φ2 Φ2 Φ4 Φ4 θ12+Φ2+θ23

22. Grid Network Φ2 Φ2 2 1 Φ4 Φ4 Φ2 Φ2 Φ4 Φ4 θ12+Φ2 θ12 Time 0 3 4 Φ2 Φ2 Φ2 Φ4 Φ2 Φ4 Φ4 Φ4 θ12+Φ2+θ23 θ12+Φ2+θ23+Φ4+θ34 θ12+Φ2+θ23+Φ4

23. Grid Network Φ2 Φ2 2 1 Φ4 Φ4 Φ2 Φ2 Φ2 Φ4 Φ4 θ12 θ12+Φ2+θ23+Φ4+θ34+Φ2+θ41+Φ4 3 4 Φ2 Φ2 Φ2 Φ4 Φ2 Φ4 Φ4 Φ4 θ12+Φ2+θ23 θ12+Φ2+θ23+Φ4+θ34 θ12+Φ2+θ23+Φ4+θ34+Φ2

24. Grid Network θ12+Φ2+θ23+Φ4+θ34+Φ2+θ41+Φ4 = NC θij = tij = Lij /Sij Φ2 + Φ4 = C 4θij+2C = NC 4θij = NC θij = NC/4 = C/4

25. Example • For a grid one-way street network, each block has 300 ft. Suppose both directions at each signal have the same phase splits. • (1) What would be the cycle length if the progression speed is designed to be 20 mph? • (2) If the cycle length is 60 sec, what would be the fastest progression speed?