CMF / CRF Details
Install oversized chevron signs
Countermeasure ID: 8981
Description: Curve warning treatment with oversized chevron signs
Prior Condition: smaller 12x18in or 24x30in signs
Category: Signs
Study: Safety Evaluation of Two Curve Warning Treatments: In-Lane Curve Warning Pavement Markings and Oversized Chevron Signs, Lyon et al., 2017
| Crash Modification Factor (CMF) |
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| Value: | 0.756 |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 0.25 |
| Crash Reduction Factor (CRF) |
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| Value: | 24.4 (This value indicates a decrease in crashes) |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 25 |
| Applicability |
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| Crash Type: | Other |
| Crash Severity: | All |
| 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: | |
| Minimum Speed Limit: | |
| Maximum Speed Limit: | |
| Speed Unit: | |
| Speed Limit Comment: | |
| Area Type: | Not specified |
| Traffic Volume: | Minimum of 173 to Maximum of 27235 Annual Average Daily Traffic (AADT) |
| Average Traffic Volume: | |
| Time of Day: | Night |
| 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: | |
| Municipality: | |
| State: | IA,KS,MO |
| Country: | USA |
| Type of Methodology Used: | Before/after using empirical Bayes or full Bayes |
| Sample Size (crashes): | 103 crashes before, 50 crashes after |
| Sample Size (sites): | 91 sites before, 91 sites after |
| Sample Size (miles): | 19.57 miles before, 19.57 miles after |
| Sample Size (miles): | 223.25 mile-years before, 139.36 mile-years after |
| Other Details |
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| Included in Highway Safety Manual? | No |
| Date Added to Clearinghouse: | Nov 17, 2017 |
| Comments: | This cmf applies to nighttime run-off road crashes. Small sample size, use with caution |
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