2012 Minnesota DOT – ACEC Annual Consultant Conference

1. 2012 Minnesota DOT – ACEC Annual Consultant Conference Alternatives to Advanced Preemption at Railroad Crossings

2. 2012 Minnesota DOT – ACEC Annual Consultant Conference What is Railroad Preemption at a Grade Crossing?

3. 2012 Minnesota DOT – ACEC Annual Consultant Conference Railroad Preemption: A special control mode in a traffic signal controller designed to start up and clear any vehicular traffic on the roadway approach crossing the railroad tracks Then allows only traffic movements that do not conflict with the railroad for the duration of the train movement

4. 8 3 Terminate any allowable combination of phases and associated pedestrian movements. 2 5 2012 Minnesota DOT – ACEC Annual Consultant Conference 1 6 7 4

5. 8 3 Display Green for Track Clearance Movements and hold in Green until railroad gates are down. 2 5 2012 Minnesota DOT – ACEC Annual Consultant Conference 1 6 7 4

6. 8 3 Allow only those phases or movements that do not conflict with crossing until preemption ends. 2 5 2012 Minnesota DOT – ACEC Annual Consultant Conference 1 6 7 4

7. 8 3 Allow only those phases or movements that do not conflict with crossing until preemption ends. 2 5 2012 Minnesota DOT – ACEC Annual Consultant Conference 1 6 7 4

8. 8 3 Allow only those phases or movements that do not conflict with crossing until preemption ends. 2 5 2012 Minnesota DOT – ACEC Annual Consultant Conference 1 6 7 4

9. 2012 Minnesota DOT – ACEC Annual Consultant Conference What is Advanced Preemption?

10. 2012 Minnesota DOT – ACEC Annual Consultant Conference Advanced Preemption is an operating mode which allows the traffic signal to display green to clear the track before the railroad flashing lights begin to operate

11. 8 3 Track clearance green interval begins 2 5 2012 Minnesota DOT – ACEC Annual Consultant Conference 1 6 7 4

12. 8 3 Railroad warning devices begin to operate 2 5 2012 Minnesota DOT – ACEC Annual Consultant Conference 1 6 7 4

13. 8 3 End track clearance green 2 5 2012 Minnesota DOT – ACEC Annual Consultant Conference 1 6 7 4

14. 2012 Minnesota DOT – ACEC Annual Consultant Conference That seems simple enough, what’s the issue here?

15. 2012 Minnesota DOT – ACEC Annual Consultant Conference When preemption is implemented, adequate time must be provided in order to permit a Design Vehicle to clear the crossing prior to the arrival of the train 75’ in MN

16. 2012 Minnesota DOT – ACEC Annual Consultant Conference 101’ So how much time does it take for preemption to operate? In this example, 52 seconds is required.

17. 2012 Minnesota DOT – ACEC Annual Consultant Conference Minimum Green = 7 seconds Pedestrian Change = 29 seconds Yellow Change = 4 seconds Red Clearance = 2 seconds 32 seconds of Advanced Preemption Time required at this location

18. 2012 Minnesota DOT – ACEC Annual Consultant Conference The required amount of time must be provided by the railroad train detection circuitry

19. 2012 Minnesota DOT – ACEC Annual Consultant Conference MUTCD requires that the railroad must provide a minimum 20 seconds of warning prior to the arrival of a through train

20. 2012 Minnesota DOT – ACEC Annual Consultant Conference Any time required beyond the minimum warning time prior to the arrival of a train becomes an addition to a basic warning system project

21. 2012 Minnesota DOT – ACEC Annual Consultant Conference In a nutshell.. Time = $$$

22. 2012 Minnesota DOT – ACEC Annual Consultant Conference Why? Substantial additional circuitry due to electrical design limitations of the train detection equipment Railroad train control signal system must co-exist with crossing systems Remote equipment locations which may be 1000’s of feet from the crossing Extensive underground cabling to remote locations

23. 2012 Minnesota DOT – ACEC Annual Consultant Conference What are the alternatives to advanced preemption or lengthy advanced preemption times?

24. 2012 Minnesota DOT – ACEC Annual Consultant Conference Turn off the traffic signal Effective? Practical?

25. 2012 Minnesota DOT – ACEC Annual Consultant Conference Grade Separate the Crossing Even more $$$

26. 2012 Minnesota DOT – ACEC Annual Consultant Conference Close the Crossing Never a popular choice with local politicians

27. 2012 Minnesota DOT – ACEC Annual Consultant Conference Practical Engineering Solutions

28. 2012 Minnesota DOT – ACEC Annual Consultant Conference Pedestrian Treatments Crosswalk Elimination

29. 2012 Minnesota DOT – ACEC Annual Consultant Conference From our example, the Pedestrian Change Time is 29 seconds Engineering changes to the intersection can reduce the time required from the railroad

30. 2012 Minnesota DOT – ACEC Annual Consultant Conference In many cases, there is no sidewalk present between the track and the parallel roadway

31. 2012 Minnesota DOT – ACEC Annual Consultant Conference Eliminate the crosswalk parallel and closest to the track Can save 2 – 4 seconds of pedestrian change time

32. 2012 Minnesota DOT – ACEC Annual Consultant Conference Pedestrian Treatments Refuge Islands

33. 2012 Minnesota DOT – ACEC Annual Consultant Conference Installing pedestrian refuge islands to shorten the distance and required pedestrian clearance time

34. 2012 Minnesota DOT – ACEC Annual Consultant Conference This permits the required pedestrian clearance time to be reduced by approximately 50% depending on crosswalk lengths

35. 2012 Minnesota DOT – ACEC Annual Consultant Conference New Technology Queue Cutter Signal

36. 2012 Minnesota DOT – ACEC Annual Consultant Conference A Queue Cutter Signal is the most cost effective tool available to reduce advance preemption time

37. 2012 Minnesota DOT – ACEC Annual Consultant Conference A Queue Cutter Signal is a separate traffic control signal installed at a grade crossing

38. 2012 Minnesota DOT – ACEC Annual Consultant Conference A queue cutter signal is not connected to or operated as a part of a downstream signalized intersection

39. 2012 Minnesota DOT – ACEC Annual Consultant Conference Generally, a queue cutter signal is installed where the Clear Storage Distance exceeds 400 - 450’

40. Typical Queue Cutter Signal Layout 2012 Minnesota DOT – ACEC Annual Consultant Conference 200 – 250’ Varies Queue Loops Queue loops must use fail-safe design and vital loop processor system Each loop wire has 2 independent loop circuits – a detect loop and a check loop Queue cutter signal flashes red if there is a loop system failure

41. 2012 Minnesota DOT – ACEC Annual Consultant Conference Queue Cutter Signal in Los Angeles

42. 2012 Minnesota DOT – ACEC Annual Consultant Conference Queue Cutter Signal in Los Angeles

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44. 2012 Minnesota DOT – ACEC Annual Consultant Conference It is interconnected with the railroad warning system with a small amount of advance preemption time This allows time for the queue cutter to change to red before the railroad flashing lights activate

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48. 2012 Minnesota DOT – ACEC Annual Consultant Conference When is a Queue Cutter not a Queue Cutter? When it’s a Pre-Signal

49. 2012 Minnesota DOT – ACEC Annual Consultant Conference Installed like a Queue Cutter Looks like a Queue Cutter Too close to the downstream intersection to use queue detection

50. 2012 Minnesota DOT – ACEC Annual Consultant Conference A Pre-Signal still requires full Advanced Preemption Time from the railroad Why?