CMF / CRF Details

CMF ID: 4112

Improve signal visibility, including signal lens size upgrade, installation of new back-plates, addition of reflective tapes to existing back-plates, and installation of additional signal heads

Description: 4-leg intersections with 3 or 4 lanes on each approach and 50 km/h posted speed

Prior Condition:  Smaller signal lens size, old back-plates, no reflective tapes on existing back-plates, and less number of signal heads

Category: Intersection traffic control

Study: Investigating Effect of Collision Aggregation on Safety Evaluations Using Multivariate Linear Intervention Models: Case Study of Signal Head Upgrade Program, El-Basyouny et al., 2012

Star Quality Rating:5 Stars  [View score details]
Rating Points Total:150
Crash Modification Factor (CMF)
Adjusted Standard Error:
Unadjusted Standard Error:0.029
Crash Reduction Factor (CRF)
Value:9.9  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:2.9
Crash Type:Day time
Crash Severity:O (property damage only)
Roadway Types:Not Specified
Street Type:
Minimum Number of Lanes:3
Maximum Number of Lanes:4
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:
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:Minimum of 4637 to Maximum of 51743 Average Daily Traffic (ADT)
Minor Road Traffic Volume:Minimum of 134 to Maximum of 48906 Average Daily Traffic (ADT)
Average Major Road Volume :20876 Average Daily Traffic (ADT)
Average Minor Road Volume :11014 Average Daily Traffic (ADT)
Development Details
Date Range of Data Used:1999 to 2004
Municipality:British Columbia
Type of Methodology Used:Before/after using empirical Bayes or full Bayes
Sample Size (crashes):4690 crashes before, 2460 crashes after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Nov 01, 2012
Comments:3 CMF sets are presented: crash severity only, time of day only, severity and time of day. Only disaggregate set (severity and time of day) is reported