Rectangular Rumble Strip Safety Evaluation

Status: Complete
Report Date: 06/01/2020

Summary:

This evaluation determined the change in crash frequency, type or severity associated with longitudinal rectangular rumble strips on rural two-lane undivided and rural four-lane divided Minnesota roadways constructed between 2012 and 2018. Crash Modification Factors (CMFs) were estimated using cross-sectional analysis to compare crash experience of locations with (i.e., centerline only, centerline + shoulder, or shoulder only) and without rectangular rumble strips. The cross-sectional analysis matched sites with and without rumble strips using matched-pair comparisons. Negative Binomial (NB) or Poisson log-linear regression models were used as appropriate to model the crashes at all treatment and non-treatment sites. There was a total of approximately 1,200 miles of treated (i.e., centerline only, centerline + shoulder, or shoulder only) and untreated sites on rural two-lane roads; and approximately 35 miles of treated (i.e., shoulder rumble strips) and untreated sites on rural four-lane divided roads. On rural two-lane undivided roads, the CMF for centerline + shoulder rumble strips is 0.73 for all crashes; shoulder only rumble strips have a CMF of 0.68 for all crashes. For single vehicle run-off-the-road crashes on rural two-lane highways, the CMF for rumble strips on the centerline + shoulder is 0.68; the CMF for shoulder only rumble strips is 0.76. The CMF for head-on, or opposite direction sideswipe crashes on rural two-lane roads with center-line and shoulder rumble strips is 0.64. On rural four-lane divided roads the CMF for shoulder rumble strips for all crashes is 0.66, and 0.40 for single vehicle run off the road crashes.

Final Deliverables:

Report #2020-07

Research & Innovation