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Between 2018 and 2019, MnDOT installed a lane constrictor design at 66 side-street, stop-controlled intersections in Minnesota. The lane constrictor design narrows the lane width for mainline approaches via a striped median with centerline rumble strips. By narrowing the mainline lane, the goal of this design is to encourage mainline traffic to slow down as it approaches the intersection. The striped median also provides greater separation between mainline directions and draws more attention to the location of the intersection. Following the installation of lane constrictors at MnDOT intersections, overall crash rates have seen little change but there have been decreases in fatal and serious injury (KA) as well as fatal and all injury (KABC) crash rates. These results indicate the addition of lane constrictors have a positive impact on crashes by reducing the severity of crashes, swapping injury crashes for property damage only crashes.

Between 2010 and 2022, 83 J-turn intersections were installed on Minnesota Department of Transportation (MnDOT) roadways. The J-turn is an alternative intersection layout that is intended to provide safety benefits by limiting the number of points within an intersection that two or more vehicle paths might intersect. Before-after analyses at J-turns and control sites were conducted and compared. With the installation of a J-turn, the analyses found decreases in fatal and serious injury crashes, angle crashes, and fatal and serious injury angle crashes. The large decreases in severe crashes at J-turn locations indicate the J-turn can be an effective safety treatment. The analysis also found J-turns have lower crash rates for key crash types as compared to low-volume interchanges and rural, high-speed signalized intersections.

Between 2016 and 2021, MnDOT installed retroreflective signal backplate borders at 116 signalized intersections in Minnesota. Retroreflective signal backplate borders are intended to further increase visibility of the signal head both during the day and at night. The goal of installing retroreflectivity to backplates is to reduce crashes at the intersection by drawing more attention to the current phase of the signal. Backplates with retroreflective borders are listed as a Federal Highway Administration Proven Safety Countermeasure with a listed safety benefit of a 15% reduction in total crashes. With the installation of retroreflective signal backplates on MnDOT signals, the changes in crash rates were not found to be statistically significantly different from similar locations that did not have retroreflective signal backplates. These results indicate there has been little impact on crash rates in the few years after the installation of retroreflective signal backplates.

Between 2010 and 2020, 49 Reduced Conflict Intersections (RCIs) were installed on Minnesota Department of Transportation (MnDOT) roadways. The RCI is an alternative intersection layout that is intended to provide safety benefits by limiting the number of points within an intersection that two or more vehicle paths might intersect. Both a before-after analysis at RCIs and a cross-sectional analysis comparing RCIs to untreated intersections were conducted. With the installation of an RCI, both analyses yielded statistically significant decreases in fatal and serious injury crashes, angle crashes, and fatal and serious injury angle crashes. Statistically significant increases in rear-end crashes were found. Both analyses showed no significant changes to sideswipe crashes or total crashes. Based on these results, severity shift in crashes has been seen at the RCIs in Minnesota. The overall number of crashes have not changed, but the high-severity crashes have been reduced while property damage crashes have increased. The large decreases in severe crashes at RCI locations indicate the RCI can be an effective safety treatment.