CMF / CRF Details

CMF ID: 2947

Install median barrier


Prior Condition: No Prior Condition(s)

Category: Roadside

Study: Bayesian Analysis for Zero-Inflated Regression Models with the Power Prior: Applications to Road Safety Countermeasures, Jang et al., 2010

Star Quality Rating: 2 Stars   [View score details]
Crash Modification Factor (CMF)
Value: 0.23
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Value: 77   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Type: All
Crash Severity: All
Roadway Types: Not Specified
Number of Lanes: 4
Road Division Type:
Speed Limit:
Area Type: Rural
Traffic Volume:
Average Traffic Volume:
Time of Day: Not specified
If countermeasure is intersection-based
Intersection Type: Not specified
Intersection Geometry: Not specified
Traffic Control: Not specified
Major Road Traffic Volume:
Minor Road Traffic Volume:
Average Major Road Volume :
Average Minor Road Volume :
Development Details
Date Range of Data Used: 2001 to 2002
Country: Korea
Type of Methodology Used: Regression cross-section
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Mar-21-2011
Comments: The authors make no mention of the traffic volumes on their sample of roads. They also state that highway segments were divided into 3 categories (divided, non-intersection, or intersection) while crashes were divided by type (pedestrian or vehicle) (p. 544). However, they don't specify how they dealt with these different categories. They also state that the "current" data are from 2002 and the "historical" data are from 2001 (p. 544). Table 3 includes 2003 data, and Table 4 excludes historical data. Since the zero-inflated regression models with the power prior use both current and historical data, the true sample sizes used for the models do not seem to be given in the paper. The method is a cross-sectional analysis, but employs Baysian techniques.