CMF / CRF Details

CMF ID: 7572

Convert 2 lane roadway to 4 lane divided roadway

Description: Conversion of urban and rural two-lane roadways to four-lane divided roadways

Prior Condition: 2 lane roadway

Category: Roadway

Study: Evaluation of the Safety Effectiveness of the Conversion of Two-Lane Roadways to Four-Lane Divided Roadways: Bayesian vs. Empirical Bayes, Ahmed et al., 2015

Star Quality Rating: 3 Stars   [View score details]
Crash Modification Factor (CMF)
Value: 0.236
Adjusted Standard Error:
Unadjusted Standard Error: 0.072
Crash Reduction Factor (CRF)
Value: 76.4   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 7.21
Crash Type: All
Crash Severity: All
Roadway Types: Not specified
Number of Lanes: 2
Road Division Type: Undivided
Speed Limit:
Area Type: Urban
Traffic Volume: Minimum of 18000 Average Daily Traffic (ADT)
Average Traffic Volume:
Time of Day:
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: 2002 to 2012
State: FL
Country: USA
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (sites): 26 sites before, 26 sites after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Nov-01-2015
Comments: Applies to roadways with AADT greater than or equal to 18,000