CMF / CRF Details
CMF ID: 322
Install a traffic signal (major road speed limit at least 40 mph)
Description:
Install a traffic signal (major road speed limit at least 40 mph)
Prior Condition: No Prior Condition(s)
Category: Intersection traffic control
| Crash Modification Factor (CMF) |
|---|
| Value: | 0.95 |
| Adjusted Standard Error: | 0.09 |
| Unadjusted Standard Error: | 0.08 |
| Crash Reduction Factor (CRF) |
|---|
| Value: | 5 (This value indicates a decrease in crashes) |
| Adjusted Standard Error: | 9 |
| Unadjusted Standard Error: | 8 |
| Applicability |
|---|
| Crash Type: | All |
| Crash Severity: | All |
| 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: | Urban |
| Traffic Volume: | |
| Average Traffic Volume: | |
| Time of Day: | |
| If countermeasure is intersection-based |
| Intersection Type: | Roadway/roadway (not interchange related) |
| Intersection Geometry: | 4-leg |
| Traffic Control: | Stop-controlled |
| Major Road Traffic Volume: | |
| Minor Road Traffic Volume: | |
| Average Major Road Volume : | |
| Average Minor Road Volume : | |
| Development Details |
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| Date Range of Data Used: | |
| Municipality: | |
| State: | |
| Country: | |
| Type of Methodology Used: | Before/after using empirical Bayes or full Bayes |
| Other Details |
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| Included in Highway Safety Manual? | Yes. HSM lists this CMF in bold font to indicate that it has the highest reliability since it has an adjusted standard error of 0.1 or less. However, it also includes an asterisk (*) to indicate that the CMF value itself is within the range 0.90 to 1.10, but that the confidence interval defined by the CMF ± two times the standard error may contain the value 1.0. This is important to note since a treatment with such an CMF could potentially result in (a) a reduction in crashes (safety benefit), (b) no change, or (c) an increase in crashes (safety disbenefit). HSM recommends that this CMF should be used with caution. |
| Date Added to Clearinghouse: | Dec 01, 2009 |
| Comments: | Countermeasure name changed to match HSM The number of crashes in the after period were not reported in this study, however, they have been recorded as 300 to give 10 points as a beneift of doubt for one or more of the following: (1) number of miles/sites in the reference/treatment group, (2) number of crashes in the references/treatment group, (3) reporting AADTs for the aggregate dataset but not for the disaggragate dataset used for CMF development. |
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