CMF / CRF Details
Improve left-turn lane offset to create positive offset
Countermeasure ID: 6096
Description: Improve left-turn lane offset to make the left-turn lanes with positive offset
Prior Condition: Left-turn lanes with negative offset
Category: Intersection geometry
Study: Safety Evaluation of Offset Improvements for Left-Turn Lanes, Persaud et al., 2009
Image: View the countermeasure image.
| Star Quality Rating: |  [View score details] |
| Rating Points Total: | 80 |
| Crash Modification Factor (CMF) | |
|---|---|
| Value: | 0.644 |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 0.09 |
| Crash Reduction Factor (CRF) | |
|---|---|
| Value: | 35.6 (This value indicates a decrease in crashes) |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 9 |
| Applicability | |
|---|---|
| Crash Type: | All |
| Crash Severity: | K (fatal),A (serious injury),B (minor injury),C (possible injury) |
| 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: | |
| Average Traffic Volume: | |
| Time of Day: | All |
| If countermeasure is intersection-based | |
| Intersection Type: | |
| Intersection Geometry: | 4-leg |
| Traffic Control: | |
| Major Road Traffic Volume: | Minimum of 7,150 to Maximum of 29,200 Annual Average Daily Traffic (AADT) |
| Minor Road Traffic Volume: | Minimum of 2,200 to Maximum of 13,350 Annual Average Daily Traffic (AADT) |
| Average Major Road Volume : | 18,892 Annual Average Daily Traffic (AADT) |
| Average Minor Road Volume : | 6,668 Annual Average Daily Traffic (AADT) |
| Development Details | |
|---|---|
| Date Range of Data Used: | 1983 to 2005 |
| Municipality: | |
| State: | WI |
| Country: | |
| Type of Methodology Used: | Before/after using empirical Bayes or full Bayes |
| Sample Size (crashes): | 305 crashes before, 62 crashes after |
| Sample Size (sites): | 12 sites before, 12 sites after |
| Sample Size (site-years): | 87 site-years before, 33 site-years after |
