CMF / CRF Details

CMF ID: 5231

Convert traffic signals to unconventional median U-turns

Description: Remove existing traffic signals and replace with unconventional median U-turn

Prior Condition: Three and Four-Leg Signalized Intersections

Category: Intersection geometry

Study: Safety Effect of U-Turn Conversions in Tehran: Empirical Bayes Observational Before-And-After Study and Crash Prediction Models, Leila Azizi and Abdolreza Sheikholeslami, 2013

Star Quality Rating: 4 Stars   [View score details]
Rating Points Total: 130
Crash Modification Factor (CMF)
Value: 1.132
Adjusted Standard Error:
Unadjusted Standard Error: 0.06
Crash Reduction Factor (CRF)
Value: -13.2   (This value indicates an increase in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 6
Crash Type: All
Crash Severity: All
Roadway Types: Not specified
Street Type:
Minimum Number of Lanes: 3
Maximum Number of Lanes:
Number of Lanes Direction: Both Directions
Number of Lanes Comment: Multi Lane
Crash Weather: Not specified
Road Division Type: Divided by Median
Minimum Speed Limit:
Maximum Speed Limit:
Speed Unit:
Speed Limit Comment:
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: Not specified
Traffic Control: Signalized
Major Road Traffic Volume: Minimum of 33650 to Maximum of 70579 Average Daily Traffic (ADT)
Minor Road Traffic Volume: Minimum of 9405 to Maximum of 31789 Average Daily Traffic (ADT)
Average Major Road Volume : 46666 Average Daily Traffic (ADT)
Average Minor Road Volume : 16757 Average Daily Traffic (ADT)
Development Details
Date Range of Data Used: 2001 to 2009
Country: Iran
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (crashes): 286 crashes before, 556 crashes after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Dec-02-2013