Transit Signal Priority:Managing Expectations

Kevin N. Balke, Ph.D., P.ETransLink® Research Center Director

Texas Transportation Institute

Transportation Research Board MeetingWashington D.CJanuary 13, 2002

Presentation Outline

Transit Priority Theory Historical Perspective Future Perspective

On-going Applications Implementation Issues

Managing Expectations

Historical Perspective

Driver Judgment

“Contact closure”Detection

“Preempt”Signal Operations

Intelligent Traffic Signal Priority

Transit Vehicle Knows …. Where it is Whether it needs

priority Behind Schedule Vehicle Occupancy

Its “budget” for priority

Traffic Signal Knows…. Where it is in its

timings Desired Time for

Service of Vehicle Relative “priority” of

all requests

Priority Request GeneratorsPriority Request

ServerTraffic Signal

Controller

Future TSP Perspective

Estimated Time of Desired

Service Priority Strategy

Implementations Issues

MANAGING EXPECTATIONS!!

Managing Expectations:Bus Operations

One Bus, One Route, One Trip

Multiple Buses, Multiple Routes, Multiple Trips

TRAFFIC MANAGER TRANSIT MANAGER

Managing Expectations:Scheduling

With TSP, I can better achieve

schedule!

With TSP, I can set new

aggressive schedule!

If the schedule was good in the first place, why

would I need TSP?

Managing Expectations:Responsiveness

Time Savings

To Transit

TransitFriendlyPhase

Priority Request Received

Expectation

TransitFriendlyPhase

Priority Request Serviced

TimeSavings

To Transit

OtherPhases

Reality

Managing Expectations:Time Savings

60 sec + 60 sec + 60 sec + 60 sec + 60 sec = 5 min

Expectations

10 sec + 50 sec + 0 sec + 25 sec + 30 sec = 1 min 55 sec

Reality

Managing Expectations:Coverage

Transit priority may NOT be appropriate everywhere! Tightly-timed intersections high volume, heavy

congestion Low volume intersections greater flexibility

Balance between traffic and bus operations

Future of Signal Priority

NTCIP Traffic Signal Control Working Group Tom Urbanik – Chair

Developing standards for signal priority control Rail, Emergency Vehicles, Transit,

Trucks Transit first

Completed in Summer 2002

Questions