CMF / CRF Details

CMF ID: 113

Install continuous milled-in shoulder rumble strips

Description:

Prior Condition:  No Prior Condition(s)

Category: Shoulder treatments

Study: Evaluation of the Effectiveness of Shoulder Rumble Strips on Rural Multi-lane Divided Highways In Minnesota, Carrasco et al., 2004

 
Star Quality Rating:1 Star  [View score details]
Rating Points Total:30
Crash Modification Factor (CMF)
Value:0.9
Adjusted Standard Error:0.25
Unadjusted Standard Error:0.11
Crash Reduction Factor (CRF)
Value:10  (This value indicates a decrease in crashes)
Adjusted Standard Error:25
Unadjusted Standard Error:11
Applicability
Crash Type:Run off road,Single vehicle
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
Minimum Speed Limit:
Maximum Speed Limit:
Speed Unit:
Speed Limit Comment:
Area Type:Rural
Traffic Volume:Minimum of 2000 to Maximum of 50000 Annual Average Daily Traffic (AADT)
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:
Municipality:
State:
Country:
Type of Methodology Used:Simple before/after
Other Details
Included in Highway Safety Manual?Yes. HSM lists this CMF in italics font to indicate that it has a lower reliability than bold font CMFs since it has an adjusted standard error of 0.2 to 0.3. HSM also includes an asterisk (*) to indicate that the CMF value itself is within the range 0.90 to 1.10, but that the confidence interval defined by the CMF ± two times the standard error may contain the value 1.0. This is important to note since a treatment with such an CMF could potentially result in (a) a reduction in crashes (safety benefit), (b) no change, or (c) an increase in crashes (safety disbenefit). HSM recommends that this CMF should be used with caution.
Date Added to Clearinghouse:Dec 01, 2009
Comments:Countermeasure name changed to match HSM 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.

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