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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.

This study aims to determine whether passing related maneuvers trigger the high number of fatal crashes on two-lane two-way highways. The public and others perceive that fatal head-on crashes are a result of drivers who attempt to pass others on two-lane two-way highways. Public officials advocate for additional passing lanes and four lane expansions to alleviate these fatal crashes. The Minnesota Department of Transportation (MnDOT) reviewed 251 fatal head-on crashes on Minnesota two-lane two-way highways. After careful review of police crash reports, seven (7) of 251 fatal crashes involved passing. The remaining 97% of the crashes involved vehicles drifting over the centerline, losing control of the vehicle, weather, and incorrect lane use. Drifting over the centerline alone accounted for 162 (65%) of the fatal crashes.

The first Minnesota modern roundabout was constructed in 1995. Since then, roundabouts have been built across the state by the Minnesota Department of Transportation, counties, and cities. There is no definitive count across Minnesota, but it is likely nearing 200 roundabouts across the state on all roads. They have become an increasingly popular intersection type by traffic engineers, communities, and transportation officials. The purpose of this report is to examine the safety performance of roundabouts by comparing the before construction crash rates and the after construction crash rates and traffic volume data. Overall, roundabouts are performing well when looking at the crash reduction record. Roundabouts in Minnesota have had over an 80% reduction in fatal and serious injury crashes. At the time of this report, there still has not been a multi-vehicle fatality in a roundabout in Minnesota

In 2010, the Minnesota Department of Transportation installed the first Reduced Conflict Intersection (RCI) in the City of Willmar. Since 2010, seven more were constructed, with more planned. The RCI concept is gaining popularity in several states, including Maryland, Mississippi, Missouri, North Carolina, and Wisconsin. This report includes findings from a safety performance evaluation of Minnesota Reduced Conflict Intersections. This evaluation found: - A 100% reduction of fatal and serious injury right-angle crashes - A 77% reduction of all severity right-angle crashes - A 50% reduction of injury crashes Additionally, compared to their untreated counterparts, Reduced Conflict Intersections showed significantly fewer severe right-angle crashes and severe crashes, and the crashes observed at an RCI intersection were of lower crash severity than their untreated counterparts.

By the end of 2022, nearly 450 roundabouts were installed on Minnesota roadways. An evaluation of traffic safety at roundabouts published by MnDOT in 2017 showed substantial decreases in fatal and serious injury crashes for all users at intersections after installation of a roundabout. The safety effects of roundabouts are largely due to geometric design practices that reduce the speed of motorized vehicles as they approach and travel through the intersection. The purpose of this evaluation is to determine if the safety effects seen in the 2017 evaluation still apply to roundabouts with higher levels of use by pedestrians and bicyclists. This evaluation conducts a before-after analysis of 95 roundabouts in Minnesota and an analysis comparing roundabouts to untreated intersections. With the installation of a roundabout, this study finds that the before-after analysis results in a 40% decrease in all severity injury crashes for all roadway users, a 70% decrease in fatal and serious injury crashes for bikes and pedestrians, and a 15% decrease in total pedestrian bike and pedestrian crashes. The results of the comparison analyses suggest roundabouts have better safety performance than through-stop and traffic signal-controlled intersections and similar safety performance to locations with all-way stop control. The results of this evaluation thus indicate that roundabouts can be an effective safety treatment for pedestrian and bicycle crashes.