1. Advanced Public Transit Systems (APTS) Transit ITS CEE582

2. APTS Products/Services 1.Service (Fleet) Management 2.Customer Information 3.Service Performance Monitoring 4.Vehicle Performance Monitoring 5.Incident Response 6.Wireless Communications CEE582

3. APTS Products/Services 7.Transit Signal Priority 8.Collision Avoidance 9.Fare Collection 10.Connection Protection 11.Demand-Response Routing and Scheduling Transit ITS Impacts Matrix http://web.mitretek.org/its/aptsmatrix.nsf CEE582

4. Purpose of APTS Technologies used to provide Products/Services that address Problems related to: –Efficiency –Reliability –Safety –Customer Satisfaction CEE582

5. What would you change about transit service? CEE582

6. Transit 101 Fixed-Route Service (bus, rail) –Established routes and stop sequences –Scheduled “time points” –Public timetables –Block – what a vehicle does for the day Block assignments change every day –Run – what a driver does for the day Run assignments change 3 or 4 times per year CEE582

7. Transit 101 Continued Demand-Response Service (“Dial-a-Ride”, Paratransit) –ADA Requirement –Eligibility criteria –Limited service area –Usually reserve in advance –Daily driver manifest CEE582

8. More Transit 101 Flex-Route Service –Deviates from fixed route in response to demand –Fixed end points and scheduled times CEE582

9. APTS Building Blocks CEE582

10. “Smart Bus” Components GPS Receiver On-board Computer On-board Network On-board Database Wireless Communication CEE582

11. Transit Signal Priority (TSP)

12. Problem: Transit vehicles are slow Problem: Transit vehicles are effected even more than cars by traffic lights –The number of times you stop at traffic signals has a huge impact on travel time

13. Transit Signal Priority Solution: Give transit vehicles green lights on arterials Priority Versus Preemption (emergency vehicles)

14. Transit Vehicle Priority Concerns with TSP: –Too much priority causes excessive side street delay –Giving transit vehicles priority messes up progression –Messed up progression slows buses even more –Roadway agencies don’t want to lose control of arterial

15. Transit Signal Priority (TSP) Pre-emption CEE582

16. Solution Find a graceful way of giving transit priority 1) Only change signal timing a little 2) Only change signal timing occasionally

17. Change Signal Timing A Little 1)Hold the green just a little longer to get the bus through the intersection 2)Shorten the side street green time to get the green for the bus to occur more quickly 3)Use a new traffic signal algorithm

18. Most Common Signal Logic Implementation Long Green or Short Red

19. Only Change Signal Timing Occasionally What criteria do you use to determine which buses get priority?

20. Only Change Signal Timing Occasionally Only late buses get priority Only special (Express?) buses get priority Only a few (random) buses get priority Priority is only available at some intersections Priority is only available on some corridors (bus priority corridors) Only full buses get priority

21. Limited Timing Changes Each of these approaches has a different impact on the combination of: –Size of improvements to transit –Size of impact to traffic –Distribution of those improvements / impacts –Amount of information needed to run the system

22. TSP Let’s examine how the TSP works

23. TSP Basics 1)Identify bus as it approaches intersection 2)Determine if bus deserves priority 3)Determine if signal is willing to give priority 4)Determine if priority is needed (is signal green already?) 5)Change signal 6)Let signal return to normal operation

24. Identify Approaching Bus Manual –Will driver’s use the system correctly? Automatic

25. Identify Approaching Bus Beacon (signpost) GPS + communications –To central? –To roadside? On-board dead reckoning –With DSRC (dedicated short range communications)

26. Determine if Priority Deserved 1)Which buses get priority? If all buses = easy If specific routes / runs = need data transfer 2)Transfer data to The bus The signal controller / interface A central location

27. What Buses Get Priority? If only specific buses get priority, then there must be a connection between –Vehicle ID, –Daily Vehicle Assignment table (route/run), –Route/run and signal cabinet location –Maybe a “priority table,” and –Clock

28. What Buses Get Priority? Late Bus Requires Bus ID + Route / Run + Detailed knowledge of –mid-point schedule times, and –current location

29. What Buses Get Priority? Only Full Buses Requires a current passenger count

30. What Buses Get Priority? Limited number of buses: Signal controller must keep track of –How many priority calls have been given, or –When was the last priority call made?

31. Signal Controller Checks Is controller willing to give priority? –Limits set by roadway agency Number of priority calls per hour Time required between calls Is priority needed? –What phase is the controller currently in?

32. Signal Controller If priority is permitted / needed Select appropriate action: –Hold green time –Limit other green times No pedestrian calls Shorten side street green allowed –Actuated signals –Fixed time signals –Other

33. Let Signal Return to Normal The more quickly this happens the better Exit detection versus timing Timing is dependent on speed of the vehicle and location of detection zone

35. Detection Zone Location Where is the bus stop? Advanced warning? –Speed of processing (detection to priority call) Exit zone –Reduces time taken from side streets

36. Transit Signal Priority Puget Sound Regional Implementation

37. Standard TSP Design Hardware –AVI Tag + Reader, or –Transmitter + receiver –Interface with traffic signal controller Interfaces also with central for route/run priority information –Extra readers to Give advance knowledge of bus approach Indicate bus has arrived at intersection Advise signal when bus has left intersection

38. System Configuration

39. Tag Antenna Interface Unit Tag Interface Unit for Dynamic Data Reader Cabinet TSP System Components

40. System Data Flow Diagram

41. How and Why Do We Use TSP Keep buses on time –Happy riders –More riders? Speed up buses –Happy riders –More riders? –Reduced transit cost (don’t need to build in time to the schedule) Reduce variability in travel time –Reduced transit cost (don’t need to build in time to the schedule) –Improves transfer timing (faster schedules?)

42. Operating Strategies and TSP Benefits

43. TSP Issues How much delay (mostly on side streets) does the priority system create? How many signal priority calls can be made? How much is exit detection worth? How do we control which buses get priority? What benefits do we get from TSP? How do we measure the benefits?

44. TSP Issues Side Street Delay –Effected by the type of priority calls Do we skip phases? Which phases? Do we shorten phases? Which phases? (peds?) –Number of priority calls –Size of side street versus priority direction –Existing delay on side street

45. TSP Issues How many calls can be made? –Side street delay –Effect of calls on progression –How many calls actually change the signal timing? –Can we monitor what actually happened?

46. TSP Issues Is exit detection worth the cost? –Importance of side street delay Cars Pedestrians –Importance of cost –(Note: Light rail versus bus and the issue of throughput)

47. Approximate TSP Costs per Approach Assumes underground installation Plus system engineering, integration, & on-bus equipment

48. TSP Issues What benefits do we get? –Increased transit speed –Increased transit reliability –Both speed and reliability

49. TSP Issues How do we measure the benefits / costs? –Intersection delay? Vehicle delay Person delay (needs transit ridership) –On time performance AVL / TSP calls / other –Scheduled route time Bus schedules Requires feedback to the scheduling department

50. TSP Issues - System Management Given all of the above choices, once the system is built: How do we know it is working optimally?