CMF / CRF Details

CMF ID: 4166

Changing left turn phasing on one approach from permissive to protected-permissive

Description: CMFs are calculated the intersection level and not the treated approach(es) level.

Prior Condition: Permissive only left turn phasing on the treated approach

Category: Intersection traffic control

Study: Evaluation of Safety Strategies at Signalized Intersections, Srinivasan, et al., 2011

Star Quality Rating: 4 Stars   [View score details]
Crash Modification Factor (CMF)
Value: 0.925
Adjusted Standard Error:
Unadjusted Standard Error: 0.067
Crash Reduction Factor (CRF)
Value: 7.5   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 6.7
Crash Type: Left turn
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: Not specified
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 4857 to Maximum of 74990 Annual Average Daily Traffic (AADT)
Minor Road Traffic Volume: Minimum of 1466 to Maximum of 42723 Annual Average Daily Traffic (AADT)
Average Major Road Volume : 31537 Annual Average Daily Traffic (AADT)
Average Minor Road Volume : 16292 Annual Average Daily Traffic (AADT)
Development Details
Date Range of Data Used:
Municipality: Toronto & North Carolina
State: notusa, NC
Country: Canada & USA
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (crashes): 597 crashes before, 343 crashes after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Dec-06-2012