CMF / CRF Details
CMF ID: 7996
Install left-turn lane at signalized intersection
Description:
Prior Condition: Intersections without left turn lanes
Category: Intersection geometry
Study: Safety Evaluation of Signal Installation With and Without Left Turn Lanes on Two Lane Roads in Rural and Suburban Areas, Srinivasan et al., 2014
| Star Quality Rating: |  [View score details] |
| Rating Points Total: | 115 |
| Crash Modification Factor (CMF) | |
|---|---|
| Value: | 0.748 |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 0.095 |
| Crash Reduction Factor (CRF) | |
|---|---|
| Value: | 25.2 (This value indicates a decrease in crashes) |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 9.5 |
| Applicability | |
|---|---|
| Crash Type: | All |
| Crash Severity: | All |
| Roadway Types: | Not specified |
| Street Type: | |
| Minimum Number of Lanes: | 2 |
| Maximum Number of Lanes: | 2 |
| 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: | All |
| Traffic Volume: | |
| Average Traffic Volume: | |
| Time of Day: | All |
| If countermeasure is intersection-based | |
| Intersection Type: | Not specified |
| Intersection Geometry: | 3-leg |
| Traffic Control: | Signalized |
| Major Road Traffic Volume: | Minimum of 2981 to Maximum of 18248 Annual Average Daily Traffic (AADT) |
| Minor Road Traffic Volume: | Minimum of 972 to Maximum of 13880 Annual Average Daily Traffic (AADT) |
| Average Major Road Volume : | 9199 Annual Average Daily Traffic (AADT) |
| Average Minor Road Volume : | 4847 Annual Average Daily Traffic (AADT) |
| Development Details | |
|---|---|
| Date Range of Data Used: | 1992 to 2012 |
| Municipality: | |
| State: | NC |
| Country: | |
| Type of Methodology Used: | Before/after using empirical Bayes or full Bayes |
| Sample Size (crashes): | 576 crashes before, 388 crashes after |
| Sample Size (sites): | 36 sites before, 36 sites after |
| Sample Size (site-years): | 180 site-years before, 174 site-years after |
