CMF / CRF Details

CMF ID: 9819

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)
Value: 0.841
Adjusted Standard Error:
Unadjusted Standard Error: 0.021
Crash Reduction Factor (CRF)
Value: 15.9   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 2.1
Crash Type: All
Crash Severity: O (property damage only)
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: No values chosen.
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
State: WA
Country: USA
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (crashes): 2304 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