CMF / CRF Details
CMF ID: 3340
Install variable speed limit signs
Description:
Install variable speed limit signs
Prior Condition: No variable speed limit sign present
Category: Speed management
Crash Modification Factor (CMF) |
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Value: | 0.92 |
Adjusted Standard Error: | |
Unadjusted Standard Error: | |
Crash Reduction Factor (CRF) |
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Value: | 8 (This value indicates a decrease in crashes) |
Adjusted Standard Error: | |
Unadjusted Standard Error: | |
Applicability |
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Crash Type: | All |
Crash Severity: | All |
Roadway Types: | Principal Arterial Interstate |
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: | |
Minimum Speed Limit: | 40 |
Maximum Speed Limit: | 60 |
Speed Unit: | mph |
Speed Limit Comment: | |
Area Type: | Urban |
Traffic Volume: | |
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 |
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Date Range of Data Used: | 2007 to 2009 |
Municipality: | St. Louis |
State: | MO |
Country: | U.S.A. |
Type of Methodology Used: | Before/after using empirical Bayes or full Bayes |
Sample Size (crashes): | 1636 crashes after |
Other Details |
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Included in Highway Safety Manual? | No |
Date Added to Clearinghouse: | Jun 04, 2012 |
Comments: | The crash count sum in Table S4 (p. 24) is for the 'after' period. The crash count for the 'before' period is not given. Although the crash count in the after period is substantial, the after period is only 1 year (p. 38); therefore, the crash count may give an inflated impression of the sample size. Traffic volume data is not given in this report. According to Table S2, the total length of the segments is 35.21 mi. |