Overview of

Transit Signal Priority Programin King County

Prepared byTransit Signal Priority Unit

Transit Speed & Reliability Program

The Speed & Reliability Program at King County Metro makes capital improvements designed to improve transit performance. Most projects are in partnership with local cities, and are coordinated with larger projects. Typical improvements include:

• Bus zones: upgrades, relocations, consolidations and bus bulbs• Trolley overhead modifications• Roadway improvements: HOV/BAT lanes, parking removal• Intersection improvements: turn radii, queue jumps• Traffic signals: timing and signal phasing, and

Transit Signal Priority

Goals for Transit Signal Priority (TSP)

• Increases amount of “green” time at intersections for selected bus trips

• Decrease average travel time• Decrease variation in travel time• Reduce signal related delay• Minimize impact on general traffic

TSP Operating Philosophy

• Conditional priority rather than hand pre-empt

• Maintain signal coordination• Concept of “green time” as a

scarce resource led to

Transit Priority Request System

Background on TPR System Selection

• Functional specifications developed by Regional Oversight Committee (ROC)

• Used negotiated Procurement process: price consideration but no low bid selection process

• Contract awarded to McCain Traffic for system development, integration and testing

• 99% read accuracy required• Final contract closeout scheduled for

December 2001

TPR Field Equipment

TPR Field Components

TagAntenna

TPR Generator

Tag Interface Unit for Dynamic Data

Reader Cabinet

TPR Tag Interface Unit (TIU)

• Supplies route/run from AVL system to TPR system

• Dynamic data enables trip level discrimination

• TIU is interim arrangement until full feature “Smart Bus” is available

• TIU does not supply data relocated to passenger schedule

TPR Transponder “Tag”

• Amtech slot tag• 904-921 MHz “spread

spectrum” band• Field disturbance device• 128 bit data packet:

– system – run– agency – trip– vehicle ID – class– driver ID –

lateness– route –

ridership

• No input by driver required

TPR Antenna

• Log-Periodic (pictured)– unobtrusive– suitable for most

applications• Yagi (not pictured)

– Used for longer range applications

TPR Reader

• Functions:– Detect tag– Acquire tag and

validate data– Transfer data to

interface unit

TPR Request Generator -specifications

• Compact size– 8.5” wide, 8” deep– 5.25” tall

• Serviceable– Connections at front

panel

• PC-104 bus– Environmentally rugged– Modular– Off-the-shelf

components

TPR Generator - Functions

• Interfaces with traffic controller

• Determines if bus is eligible for priority

• If eligible, places a request for priority to traffic controller

• Stores and logs priority settings

Conditional Priority Requests

• Issued by TPR Generator

• Request based upon– Time of Day– Frequency of Request– Vehicle ID– Bus Direction– Route Information– Lateness (Future)– Ridership (Future)

TPR Data Files

• Settings– Time of Day plans (TOD)– Eligible Vehicle Tables (EVT)

• Logs– Operations Logs– Transponder (Tag) Logs

TPR System Flow Diagram

Roles and Responsibilities in Initial TSP Implementation

• Traffic Jurisdictions– Participate in selection,

approval and design of TPR installations

– Approve the TSP Operating Plan

– Establish transit priority control strategy that will be implemented

– Insure that its traffic control system has the required functionality

• Transit Agency– Propose location for TPR

equipment and develop draft TSP Operating Plan

– Support traffic engineer in evaluation/selection of TSP. compatible traffic control equipment

– Lead final design effort or approve final PS and E documents for TPR system

Roles and Responsibilities in Initial TSP Implementation - continued

• Traffic Jurisdiction– Establish frequency

with which buses can request priority

– In future, further discriminate calls based on passenger loads and schedule adherence

– Set “budget” for green time for buses within signal timing plans

• Transit Agency– Determine which

vehicles/trips will be eligible for performance

– After initial activation, monitor system performance and request adjustments from traffic engineer as needed

– Update transit operation plan if required.

Roles and Responsibilities in Initial TSP Implementation - continued

• Traffic Jurisdiction– Optimize signal timing

prior to initial implementation of TSP.

– Assist in testing and acceptance of TPR system

– Assist in evaluation and adjustment of initial TSP settings

• Transit Agency– Lead the testing and

acceptance effort for all new TPR installations

– Provide system integration support

– Lead effort to evaluate and adjust initial TSP settings

Roles and Responsibilities in TSP Operation - ongoing

• Traffic Jurisdiction– Coordinate future changes in

signal timing that impact TSP intersections with transit agency

– Review all proposed TSP. adjustments; accept and implement, or modify, or reject

– Participate in the TSP Regional Oversight Committee

– Support continued development of TSP. Functionality in traffic control system

• Transit Agency– Responsible for ongoing

TSP system evaluation– Propose adjustments to TPR

settings set by city or to TSP traffic control strategies employed by city

– Convene regular meetings of a TSP Regional Oversight Committee composed of users to guide continued system development, including enhanced functionality.

Roles and Responsibilities in TPR Maintenance - ongoing

• Traffic Jurisdiction– Owns and maintains all TPR

equipment in the street, including communication links

– Responsible for power for street equipment

– Coordinates repairs with transit agency in agreed upon response time

– Maintain TPR equipment consistent with configuration management plan

• Transit Agency– Owns and maintains all aspects

of the TPR system from the modem back to the server.

– Maintain system access for all participants; serves as network administrator

– Monitor system and notify traffic jurisdictions when field equipment is not functioning

– Responsible for developing and implementing a configuration management plan

TSP Development Considerations

• Expect a steep learning curve with local traffic engineers; TPR/traffic control system integration is very labor intensive and highly technical

• TPR design is a highly interactive process; – adjustments in bus stop spacing/ location may be

required to make TSP feasible– availability of interconnect, poles and power are

limiting factors; city’s ability/willingness to provide interconnect significantly impacts cost

– Rf field surveys are required to site and order TPR equipment

TSP Development Considerations - continued

• Few local consultants are familiar with TPR system design requirements

• Need to insure that existing traffic control cabinets have space for TPR equipment

• Need to secure commitments that traffic engineer will “exercise” TSP in a manner that makes a TPR investment worthwhile

• O and M issues should be resolved as part of the up front project planning/financing

Overview of TSP System Development

• Community Transit, Everett Transit and King County Metro will all utilize Rf-based bus detection developed by McCain; Pierce Transit will use Opticom

• Metro KC is prepared to administer the TPR Management System for King County

• O and M principles/expectation have been established for all active TSP projects sponsored by King County Metro

Overview of TSP System Development - continued

• City of Seattle and King County have operating experience with initial installations; King County is funding a Traffic Technician for the City of Seattle to support new TSP installations over the next 2 years

• KC Metro has a contract with Econolite to add improved TSP functionality to the AC2 controller; deliverables are due in July, 2002

• City of Seattle is leading effort to improve TSP functionality in the Eagle and PEEK controllers

• Bellevue has added TSP functionality to their Computrans traffic control system and will first apply it to a two intersection demonstration that is under development

Overview of TSP System Development - continued

• King County has put a TPR parts contract in place with McCain Traffic; McCain Traffic has agreed to supply this equipment to any public agency for the same terms.– Equipment prices and escalation factors are set for a period of

3 years. – King County will insure that the parts list is kept current– All pricing has been subject to a FTA compatible cost/price analysis– Agencies must exercise this option within the constraints of their

own purchasing rules and regulations.

• King County has a new contract with McCain for enhancements to the TPR system; new functionality will be added in modules over a period of two years. Development priority will be given to those modules that can improve TSP performance.

Project Design Issues

• Renton TSP • First Ave S TSP

Project Design Issues continuedRenton TSP

Project Design Issues continuedFirst Ave S TSP