CMF / CRF Details
CMF ID: 9716
Install alternative audible lane departure warning treatments
Description: Alternate systems typically include profile (audible) pavement markings and preformed rumble bars. Similar to rumble strips, profile pavement markings and rumble bars are intended to alert drivers that they are leaving their lanes through auditory and tactile warnings. The main difference is that rumble strips are typically milled or rolled into the pavement, while the profile pavement markings and rumble bars are usually installed on the markings. These countermeasures are commonly used on seal coat (chip seal) road surfaces where milled rumble strips cannot be utilized or on roadways where shoulders are too narrow for milled rumble strips.
Prior Condition: No Prior Condition(s)
Category: Shoulder treatments
Study: Safety Evaluation of Alternative Audible Lane Departure Warning Treatments in Reducing Traffic Crashes: an Empirical Bayes Observational Before-After Study, Wu et al., 2018
| Star Quality Rating: |  [View score details] |
| Rating Points Total: | 90 |
| Crash Modification Factor (CMF) | |
|---|---|
| Value: | 0.68 |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 0.09 |
| Crash Reduction Factor (CRF) | |
|---|---|
| Value: | 32 (This value indicates a decrease in crashes) |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 9 |
| Applicability | |
|---|---|
| Crash Type: | Head on,Run off road,Sideswipe |
| Crash Severity: | K (fatal),A (serious injury),B (minor injury),C (possible injury) |
| 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: | Undivided |
| Minimum Speed Limit: | |
| Maximum Speed Limit: | |
| Speed Unit: | |
| Speed Limit Comment: | |
| Area Type: | Rural |
| Traffic Volume: | Minimum of 237 to Maximum of 3880 Average Daily Traffic (ADT) |
| Average Traffic Volume: | 12681 Average Daily Traffic (ADT) |
| Time of Day: | Not specified |
| If countermeasure is intersection-based | |
| Intersection Type: | |
| Intersection Geometry: | |
| Traffic Control: | |
| Major Road Traffic Volume: | |
| Minor Road Traffic Volume: | |
| Average Major Road Volume : | |
| Average Minor Road Volume : | |
| Development Details | |
|---|---|
| Date Range of Data Used: | 2012 to 2016 |
| Municipality: | TxDOT's Atlanta District |
| State: | TX |
| Country: | USA |
| Type of Methodology Used: | Before/after using empirical Bayes or full Bayes |
| Sample Size (crashes): | 63 crashes after |
| Sample Size (sites): | 33 sites before, 33 sites after |
| Sample Size (site-years): | 99 site-years before |
| Sample Size (miles): | 189 miles before, 189 miles after |
| Sample Size (miles): | 567 mile-years before |
| Other Details | |
|---|---|
| Included in Highway Safety Manual? | No |
| Date Added to Clearinghouse: | Oct 27, 2018 |
| Comments: | CMF for single vehicle run-off-road crashes and opposite direction crashesSPF from the HSM was used |
