CMF / CRF Details

CMF ID: 1433

Improve visibility of signal heads


Prior Condition:  Improvements included one or more of the following: signal lens size upgrade, installing new backboards, adding reflective tapes to existing backboards, and installing additional signal heads.

Category: Intersection traffic control

Study: Evaluating the Safety Impacts of Improving Signal Visibility at Urban Signalized Intersections, Sayed et al., 2007

Star Quality Rating:4 Stars  [View score details]
Rating Points Total:120
Crash Modification Factor (CMF)
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Value:6  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:
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:50
Maximum Speed Limit:50
Speed Unit:km/h
Speed Limit Comment:50 km/h or 30 mph
Area Type:Urban
Traffic Volume:
Average Traffic Volume:
Time of Day:Day
If countermeasure is intersection-based
Intersection Type:Roadway/roadway (not interchange related)
Intersection Geometry:4-leg
Traffic Control:Signalized
Major Road Traffic Volume:
Minor Road Traffic Volume:
Average Major Road Volume :
Average Minor Road Volume :
Development Details
Date Range of Data Used:1999 to 2004
Municipality:City of Burnaby, City of Coquitlam, City of Kelowna, City of New Westminster, City of North Vancouver, City of Surrey
Type of Methodology Used:Before/after using empirical Bayes or full Bayes
Sample Size (sites):171 sites after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Dec 01, 2009
Comments: The number of crashes in the after period were not reported in this study, however, they have been recorded as 300 to give 10 points as a beneift of doubt for one or more of the following: (1) number of miles/sites in the reference/treatment group, (2) number of crashes in the references/treatment group, (3) reporting AADTs for the aggregate dataset but not for the disaggragate dataset used for CMF development.