CMF / CRF Details

CMF ID: 5458

Convert an open median to a directional median

Description: Convert a full median opening to a directional median opening

Prior Condition: Roadway with full median openings

Category: Access management

Study: Safety Effects of Median Treatments Using Longitudinal Channelizers: Empirical Bayesian Before-and-After Study, Zhou et al., 2013

 
Star Quality Rating: 3 Stars   [View score details]
Crash Modification Factor (CMF)
Value: 0.43
Adjusted Standard Error:
Unadjusted Standard Error: 0.0447
Crash Reduction Factor (CRF)
Value: 57   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 4.47
Applicability
Crash Type: Left turn
Crash Severity: All
Roadway Types: Principal Arterial Other
Number of Lanes: 4 to 6
Road Division Type: Divided by Median
Speed Limit: 40mph to 55 mph
Area Type: Urban and suburban
Traffic Volume: Minimum of 27000 to Maximum of 96000 Annual Average Daily Traffic (AADT)
Average Traffic Volume:
Time of Day: Not specified
If countermeasure is intersection-based
Intersection Type:
Intersection Geometry:
Traffic Control:
Major Road Traffic Volume:
Minor Road Traffic Volume:
Average Major Road Volume :
Average Minor Road Volume :
Development Details
Date Range of Data Used: 2003 to 2010
Municipality: Tampa
State: FL
Country:
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (crashes): 17 crashes after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Apr-30-2014
Comments: CMF for left-turn crashes (based on the KABCO scale). The SPF only included VMT. It was not clear if annual calibration factors or other methods were used to account for trends.