CMF / CRF Details
CMF ID: 7879
Improve pavement friction (Chip Seal)
Description:
Chip seal treatment to improve pavement friction
Prior Condition: Untreated pavements
Category: Roadway
| Crash Modification Factor (CMF) |
|---|
| Value: | 1.015 |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 0.063 |
| Crash Reduction Factor (CRF) |
|---|
| Value: | -1.5 (This value indicates an increase in crashes) |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 6.3 |
| Applicability |
|---|
| Crash Type: | Wet road |
| 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: | Wet road |
| Road Division Type: | All |
| Minimum Speed Limit: | |
| Maximum Speed Limit: | |
| Speed Unit: | |
| Speed Limit Comment: | |
| Area Type: | All |
| Traffic Volume: | Minimum of 170 to Maximum of 24792 Annual Average Daily Traffic (AADT) |
| Average Traffic Volume: | 2751 Annual Average Daily Traffic (AADT) |
| Time of Day: | Not specified |
| 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: | 2000 to 2011 |
| Municipality: | |
| State: | NC,PA |
| Country: | USA |
| Type of Methodology Used: | Before/after using empirical Bayes or full Bayes |
| Other Details |
|---|
| Included in Highway Safety Manual? | No |
| Date Added to Clearinghouse: | Nov 01, 2015 |
| Comments: | CMF for Single layer Chip seal treatment, wet-road crashes (PA and NC), All years of the after period 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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