CMF / CRF Details

CMF ID: 4113

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)
Value: 0.867
Adjusted Standard Error:
Unadjusted Standard Error: 0.052
Crash Reduction Factor (CRF)
Value: 13.3   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 5.2
Crash Type: Nighttime
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: Night
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
Country: Canada
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (crashes): 1348 crashes before, 786 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