T3 Webinar Presentation

Lessons Learned: Improving Reliability with Transit Signal Priority Systems -
King County Metro Transit and Los Angeles County MTA (January 22, 2008)

Presenter:   John Toone
Presenter's Org:   King County Metro

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T3 Webinars are brought to you by the ITS Professional Capacity Building Program (ITS PCB) at the U.S. Department of Transportation's (USDOT) ITS Joint Program Office, Research and Innovative Technology Administration (RITA)

Slide 1: Overview of King County Transit Signal Priority Program

Metro’s Countywide Signal Priority Program
T3 Webinar
January 22, 2008

Slide 2: Transit Signal Priority.Program Timeline.

  • 1991 – Rainier Ave HOV study recommends demonstration of Transit Signal Priority
  • 1993 – Regional Oversight Committee formed
  • 1994-1996 – RFI, RFP, Contract Award
  • 1997 – System design approved
  • 1999 – Rainier Ave installation
  • 2000 – Aurora Ave installation
  • 2002 – Final acceptance & Aurora Ave evaluation

Slide 3: System Requirements

  • Conditional priority
    • Data message
  • Decentralized operation
  • Work with multiple signal controller types
  • Minimal disruption to general Traffic
    • Limited call frequency
    • Must serve all phases
  • No driver interaction

[Photo of signal controller.]

Slide 4: King County TSP System

  • Detection
    • RF Tag Reader
    • 500 - 1,000 feet
  • Request
    • TPRG in signal cabinet
    • Conditional priority

[Diagram of the King Country TSP system. Shows location of signal priority equipment installed around the intersection. Installed equipment consists of 1) antenna, 2) reader, 3) traffic signal controller, 4) lonworks to interface unit. Diagram shows bus with a transponder traveling through the intersection, activating the signal priority system.]

Slide 5: TSP Transponder "Tag"

128 bit packet:

  • system
  • agency
  • vehicle ID
  • driver ID
  • route
  • run
  • trip
  • class
  • lateness
  • ridership
  • No input by driver required.

[Photo of TSP transponder tag located on the outside of the bus. ]

Slide 6: TSP Reader

  • RF antenna mounted above roadway
  • Reader detects tag, reads data packet and passes information to TPR Generator

[Photos of RF antennas.]

Slide 7: TPR Generator

  • Interfaces with traffic controller
  • Determines if bus is eligible for priority
  • Stores logs and priority logic

[Photos of traffic signal controllers.]

Slide 8: Current TSP Projects

  • Rainier Avenue
  • SR 99 North
  • SR 99 South
  • Bellevue 8th St.
  • 272nd / I-5
  • Redmond (RITS)
  • NE 124th St.
  • Renton TSP
  • Lake City Way
  • 1st Avenue South
  • Jackson St/12th Ave.
  • E-3 Busway to CBD

[Map of King County that shows the location of current TSP projects.]

Slide 9: TSP Evaluation Findings

Average reduction in bus travel peak period: 5.5%
Average reduction in bus delay at signalized intersections: 25%
Reduction in buses with travel time >30 min: 40%

Slide 10: TSP Lessons Learned

  • TSP impacts on reliability are as important as speed
  • Communication quality is critical
  • RFID is effective, but complex and a large share of installation and maintenance cost
  • No one cares more about Transit Signal Priority than Transit

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