CMF / CRF Details
Install a traffic signal and left turn lanes
Countermeasure ID: 7966
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
| Crash Modification Factor (CMF) |
|---|
| Value: | 0.541 |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 0.044 |
| Crash Reduction Factor (CRF) |
|---|
| Value: | 45.9 (This value indicates a decrease in crashes) |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 4.4 |
| 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: | Stop-controlled |
| Major Road Traffic Volume: | Minimum of 2981 to Maximum of 18248 Annual Average Daily Traffic (AADT) |
| Minor Road Traffic Volume: | Minimum of 1852 to Maximum of 13880 Annual Average Daily Traffic (AADT) |
| Average Major Road Volume : | 10169 Annual Average Daily Traffic (AADT) |
| Average Minor Road Volume : | 5970 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): | 374 crashes before, 234 crashes after |
| Sample Size (sites): | 19 sites before, 19 sites after |
| Sample Size (site-years): | 95 site-years before, 91 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. |
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