ITS and Planning for Transit Priority in Broward County, Florida

1. ITS and Planning for Transit Priority in Broward County, Florida TRB Workshop on Signal Control Priority for Transit Vehicles January 11, 2004 Lawrence T. Hagen, P.E., PTOE

4. Agenda • Background • History of project • Objective of project • Preemption vs. Priority • Lessons Learned • Future Directions • Conclusions

5. Background • Project was funded with public safety funds. • Goal was to provide preemption for emergency vehicles. • Transit priority was added as an ancillary benefit. • Objective was to accommodate both high priority calls (preemption) and low priority calls (priority).

6. GPS System Basic Operation • Vehicle GPS receiver obtains vehicle position, speed and heading information from GPS satellites • Vehicle equipment transmits this information to intersection via radio • Intersection radio receives this information. • If vehicle is approaching intersection in a predefined approach corridor and requesting priority, the phase selector provides an output to the traffic controller's preemption input • The traffic controllers preemption input is programmed to hold the green light or cycle to the green light for the approaching vehicle

9. Signal Preemption vs. Signal Priority • Preemption – a need for a special mode of operation that causes you to leave normal operation suddenly. • Priority – a need to enhance or prefer a particular movement while maintaining normal operation.

10. Normal Cycle - Preemption Call

11. Normal Cycle - Priority Call

12. Green Extension Cycle

13. Normal Cycle - Priority Call

14. Early Green Cycle

15. Lessons Learned • BE CAREFULL OF PEDESTRIAN TREATMENT • NOT ALL CONTROLLERS CAN HANDLE TRANSIT PRIORITY AND PREEMPTION • SYSTEM WORKED TOO GOOD • NOT ALL CONTROLLERS CAN HANDLE DESTINATION-SPECIFIC PREEMPTION • CONTROL SYSTEM LIMITATIONS

16. Turn Signal Monitoring • Vehicle unit senses state of the turn signals • Information is transmitted to intersection • The intersection the vehicle is approaching, can then relay the priority request to the next intersection in the direction that the vehicle will be turning • The outputs of the phase selector may also be varied depending on the state of the turn signal • This allows different greens to be displayed depending on the intended direction of the vehicle

17. Turn Signal Dependant Mode • Limiting factor will most likely be the number of preemption inputs on the controller. • Typical use would be to only display protected left turn arrow if vehicle is turning left

18. Turn Signal Dependant Mode Example

19. Broward County Traffic Control System

20. Broward County Traffic Control System

21. Normal Cycle - Priority Call

22. Early Green Cycle

23. Future Directions • Destination-specific transit priority • Example: Left-turning bus

24. Normal Cycle - Priority Call

25. Early Green Cycle

26. Normal Cycle - Priority Call

27. Early Left Cycle

28. Future Directions • Destination-specific transit priority • Example: Left-turning bus • Communication to downstream signals • Especially short block lengths without transit stops • Improved tracking systems – continuous detection

29. Conclusions • Implementing transit priority is doable, it is just not always as easy as it sounds – many issues need to be addressed. • Many existing legacy traffic systems (pre-NTCIP) may have limitations. • Standards are still in the developmental stage. • Opportunities are endless!

30. Questions? Larry Hagen hagen@cutr.usf.edu