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.
