CMF / CRF Details

CMF ID: 3035

Install raised median

Description:

Prior Condition:  no raised median

Category: Access management

Study: Analyzing Raised Median Safety Impacts Using Bayesian Methods, Schultz et al., 2011

 
Star Quality Rating:2 Stars  [View score details]
Rating Points Total:35
Crash Modification Factor (CMF)
Value:0.56
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Value:44  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:
Applicability
Crash Type:All
Crash Severity:K (fatal),A (serious injury)
Roadway Types:Not Specified
Street Type:
Minimum Number of Lanes:
Maximum Number of Lanes:
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather:Not specified
Road Division Type:Divided by Median
Minimum Speed Limit:
Maximum Speed Limit:
Speed Unit:
Speed Limit Comment:
Area Type:
Traffic Volume:Minimum of 10000 to Maximum of 55000 Average Daily Traffic (ADT)
Average Traffic Volume:
Time of Day:All
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:1998 to 2008
Municipality:
State:UT
Country:USA
Type of Methodology Used:Before/after using empirical Bayes or full Bayes
Sample Size (site-years):32 site-years before, 28 site-years after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Jul 15, 2011
Comments:The number of crashes in the after period were not reported in this study, however, they have been recorded as 300 to give 10 points as a beneift of doubt for one or more of the following: (1) number of miles/sites in the reference/treatment group, (2) number of crashes in the references/treatment group, (3) reporting AADTs for the aggregate dataset but not for the disaggragate dataset used for CMF development.