Search Content

This evaluation determined the change in crash frequency, type or severity associated with longitudinal sinusoidal rumble strips on rural two-lane undivided Minnesota roadways constructed between 2018 and 2022. Crash modification factors (CMFs) were estimated using cross-sectional analysis to compare crash experience of locations with sinusoidal rumble strips (i.e., centerline only, centerline and shoulder, or shoulder only) compared to roads with rectangular rumble strips. The cross-sectional analysis matched sites with sinusoidal and rectangular rumble strips using matched-pair comparisons. Negative binomial (NB) or Poisson log-linear regression models were used to model the crashes at all treatment and non-treatment sites. There was a total of approximately 327 miles of treated (i.e., centerline only, centerline and shoulder, or shoulder only sinusoidal rumble strips) and approximately 302 miles of untreated (i.e., centerline only, centerline and shoulder, or shoulder only rectangular rumble strips) on rural two-lane divided roads. Overall, the results of the models indicated no significant differences in crash rates between rural two-lane undivided roads with sinusoidal rumble strips, and rural two-lane undivided roads with rectangular rumble strips.

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 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 was 0.73 for all crashes; shoulder only rumble strips had 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 was 0.68; the CMF for shoulder only rumble strips was 0.76. The CMF for head-on; or opposite direction sideswipe crashes on rural two-lane roads with centerline and shoulder rumble strips was 0.64. On rural four-lane divided roads; the CMF for shoulder rumble strips for all crashes was 0.66 and 0.40 for single vehicle run-off-the-road crashes.