CMF / CRF Details

CMF ID: 108

Install snowplowable, permanent raised pavement markers (Radius less than or equal to 1640 ft)

Description: Install snowplowable, permanent raised pavement markers (Radius less than or equal to 1640 ft)

Prior Condition:  No Prior Condition(s)

Category: Delineation

Study: NCHRP Report 518: Safety Evaluation of Permanent Raised Pavement Markers, Bahar et al., 2004

 
Star Quality Rating:4 Stars  [View score details]
Rating Points Total:120
Crash Modification Factor (CMF)
Value:1.03
Adjusted Standard Error:0.13
Unadjusted Standard Error:0.11
Crash Reduction Factor (CRF)
Value:-3  (This value indicates an increase in crashes)
Adjusted Standard Error:13
Unadjusted Standard Error:11
Applicability
Crash Type:Nighttime
Crash Severity:All
Roadway Types:Not Specified
Street Type:
Minimum Number of Lanes:2
Maximum Number of Lanes:2
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather:Not specified
Road Division Type:
Minimum Speed Limit:
Maximum Speed Limit:
Speed Unit:
Speed Limit Comment:
Area Type:Rural
Traffic Volume:Minimum of 15001 to Maximum of 20000 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:Before/after using empirical Bayes or full Bayes
Other Details
Included in Highway Safety Manual?Yes. HSM lists this CMF in bold font to indicate that it has the highest reliability since it has an adjusted standard error of 0.1 or less. However, it 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 include radius measurement 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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