CMF / CRF Details
Install positive offset left turn lanes
Countermeasure ID: 2795
Description: Install offset left turn lanes to improve sight distance
Prior Condition: No Prior Condition(s)
Category: Intersection geometry
Study: NCHRP Report 650 - Median Intersection Design for Rural High-Speed Divided Highways, Maze et al., 2010
| Crash Modification Factor (CMF) |
|---|
| Value: | 0.37 |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 0.27 |
| Crash Reduction Factor (CRF) |
|---|
| Value: | 63 (This value indicates a decrease in crashes) |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 26.9 |
| Applicability |
|---|
| Crash Type: | Angle |
| Crash Severity: | All |
| Roadway Types: | Principal Arterial Other Freeways and Expressways |
| 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: | Divided by Median |
| Minimum Speed Limit: | 55 |
| Maximum Speed Limit: | 55 |
| Speed Unit: | mph |
| Speed Limit Comment: | 55 mph reduced to 45 mph |
| Area Type: | Rural |
| Traffic Volume: | |
| Average Traffic Volume: | |
| Time of Day: | All |
| If countermeasure is intersection-based |
| Intersection Type: | Roadway/roadway (not interchange related) |
| Intersection Geometry: | 4-leg |
| Traffic Control: | Stop-controlled |
| Major Road Traffic Volume: | Minimum of 26900 to Maximum of 30800 Annual Average Daily Traffic (AADT) |
| Minor Road Traffic Volume: | |
| Average Major Road Volume : | |
| Average Minor Road Volume : | |
| Development Details |
|---|
| Date Range of Data Used: | 1999 to 2005 |
| Municipality: | New Hanover County |
| State: | NC |
| Country: | USA |
| Type of Methodology Used: | Simple before/after |
| Sample Size (crashes): | 7 crashes before, 3 crashes after |
| Other Details |
|---|
| Included in Highway Safety Manual? | No |
| Date Added to Clearinghouse: | Mar 21, 2011 |
| Comments: | For 1 site. Speed limit was reduced at the site between before and after period. |
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