CMF / CRF Details
CMF ID: 5553
Converting four-lane roadways to three-lane roadways with center turn lane (road diet)
Description:
Conversion of road segments from a four-lane to a three-lane cross-section with two-way left-turn lanes (also known as road diets).
Prior Condition: 4 lane roadway
Category: Roadway
| Crash Modification Factor (CMF) |
|---|
| Value: | 0.748 |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 0.012 |
| Crash Reduction Factor (CRF) |
|---|
| Value: | 25.2 (This value indicates a decrease in crashes) |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 1.17 |
| Applicability |
|---|
| Crash Type: | All |
| Crash Severity: | All |
| Roadway Types: | Not specified |
| Street Type: | |
| Minimum Number of Lanes: | 4 |
| Maximum Number of Lanes: | 4 |
| Number of Lanes Direction: | |
| Number of Lanes Comment: | |
| Crash Weather: | Not specified |
| Road Division Type: | Undivided |
| Minimum Speed Limit: | |
| Maximum Speed Limit: | |
| Speed Unit: | |
| Speed Limit Comment: | |
| Area Type: | Urban |
| Traffic Volume: | Minimum of 2030 to Maximum of 15350 Annual Average Daily Traffic (AADT) |
| 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 |
|---|
| Date Range of Data Used: | 1982 to 2004 |
| Municipality: | |
| State: | IA |
| 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: | Aug 12, 2014 |
| Comments: | CMF calculation is for reduction in crash frequency per mile.
The sites used for the development of this CMF were largely located in smaller urban areas. 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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