CMF / CRF Details

CMF ID: 1417

Add signal (additional primary head)


Prior Condition: Intersection has one primary signal head per approach

Category: Intersection traffic control

Study: Safety Benefits of Additional Primary Signal Heads, Felipe et al., 1998

Star Quality Rating: 3 Stars   [View score details]
Crash Modification Factor (CMF)
Value: 0.72
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Value: 28   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Type: Rear end
Crash Severity: All
Roadway Types: Not specified
Number of Lanes:
Road Division Type:
Speed Limit:
Area Type: Urban
Traffic Volume:
Average Traffic Volume:
Time of 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:
Municipality: Richmond, British Columbia
Country: Canada
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (sites): 8 sites after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Dec-01-2009
Comments: The authors state that "three year of data were used for this analysis" (p. 7). This statement does not indicate if the before period was 3 years, the after period was 3 years, both were 3 years, or the total time period was 3 years (i.e. 1.5 years for before period and 1.5 years for after period).