CMF / CRF Details

CMF ID: 9664

Implement transit signal priority

Description: Transit signal priority (TSP) is a type of transit preferential treatment implemented at signalized intersections to reduce (bus or urban rail) transit delays by providing extended or early green time 3 to transit vehicles in operation.

Prior Condition:  No TSP

Category: Transit

Study: Assessing Effects of Transit Signal Priority on Traffic Safety: Empirical Bayes Before-After Study Using King County, Washington Data, Song and Noyce, 2018

Star Quality Rating:5 Stars  [View score details]
Rating Points Total:140
Crash Modification Factor (CMF)
Adjusted Standard Error:
Unadjusted Standard Error:0.018
Crash Reduction Factor (CRF)
Value:12.7  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:1.8
Crash Type:All
Crash Severity:All
Roadway Types:Not specified
Street Type:
Minimum Number of Lanes:
Maximum Number of Lanes:
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather:Not specified
Road Division Type:
Minimum Speed Limit:
Maximum Speed Limit:
Speed Unit:
Speed Limit Comment:
Area Type:Urban
Traffic Volume:
Average Traffic Volume:
Time of Day:Not specified
If countermeasure is intersection-based
Intersection Type:Roadway/railroad grade crossing
Intersection Geometry:
Traffic Control:Signalized
Major Road Traffic Volume:Minimum of 7268 to Maximum of 44576 Annual Average Daily Traffic (AADT)
Minor Road Traffic Volume:
Average Major Road Volume :26705 Annual Average Daily Traffic (AADT)
Average Minor Road Volume :
Development Details
Date Range of Data Used:2002 to 2015
Municipality:King County
Type of Methodology Used:Before/after using empirical Bayes or full Bayes
Sample Size (crashes):3634 crashes after
Sample Size (sites):11 sites before, 11 sites after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Oct 27, 2018