CMF / CRF Details
CMF ID: 7977
Install a traffic signal and left turn lanes
Description: Install a traffic signal and left turn lanes
Prior Condition: Intersections with a stop sign on minor roads
Category: Intersection traffic control
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: | 122 |
| Crash Modification Factor (CMF) | |
|---|---|
| Value: | 0.711 |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 0.052 |
| Crash Reduction Factor (CRF) | |
|---|---|
| Value: | 28.9 (This value indicates a decrease in crashes) |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 5.2 |
| Applicability | |
|---|---|
| Crash Type: | Rear end |
| 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,4-leg |
| Traffic Control: | Stop-controlled |
| Major Road Traffic Volume: | Minimum of 1360 to Maximum of 18248 Annual Average Daily Traffic (AADT) |
| Minor Road Traffic Volume: | Minimum of 1036 to Maximum of 13880 Annual Average Daily Traffic (AADT) |
| Average Major Road Volume : | 11896 Annual Average Daily Traffic (AADT) |
| Average Minor Road Volume : | 6249 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): | 379 crashes before, 313 crashes after |
| Sample Size (sites): | 67 sites before, 67 sites after |
| Sample Size (site-years): | 333 site-years before, 319 site-years after |
| Other Details | |
|---|---|
| Included in Highway Safety Manual? | No |
| Date Added to Clearinghouse: | Nov 10, 2016 |
| Comments: | The CMF was developed for both rural and suburban areas. |
