Fleming, Katie

In July of 2009, the Minnesota Department of Transportation (MnDOT) Office of Traffic Safety, and Technology (OTST), Department of Public Safety (DPS) Offices of Traffic Safety (OTS) along with the Minnesota State Highway Patrol (MSP) collaborated to develop an aggressive driving education and enforcement campaign – High Enforcement of Aggressive Traffic (HEAT). The HEAT Project began July 2009 and concluded July 2012. The three-year program aimed to improve roadway safety through education and heightened traffic enforcement. Minnesota State Patrol troopers and local law enforcement officers provided heightened enforcement through overtime hours.

From 2008-2012, lane departure crashes accounted for 46% of all severe crashes, 45% of all fatal and serious lane departure crashes occurred on a 2-lane, 2-way road, and 45% of all fatal and serious injury lane departure crashes occurred on county roads. (Minnesota Department of Transportation, 2014). In an effort to reduce roadway departure crashes, MnDOT funded the installation of six-inch edge lines on over 3,000 miles of county and township roads. Wider edge lines offer clear delineation of the roadway edge. Standard roadway edge lines measure four-inches wide. The six-inch edge lines provide additional guidance and help drivers avoid leaving the roadway to the right. In a three state evaluation of wider edge lines, Park, et al. found wider edge lines significantly reduced total crashes, fatal and injury crashes in Kansas and Illinois, and single vehicle night crashes (Park, Carlson, Porter, & Andersen, 2012). The results for each state varied; total crash reductions ranged from 17.5 to 30.1% reduction, fatal and injury crash reduction ranged 36.5 to 37.7% reduction, and single vehicle, night crash reductions ranged from 18.0 to 29.5% (Park, Carlson, Porter, & Andersen, 2012).

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.

This Sinusoidal Rumble Strip Design Optimization Study presents results of sound level monitoring of four types of centerline rumble strips installed along Trunk Highway (TH) 18 in Mille Lacs and Aitken counties in Minnesota. This study is in response to objections raised by some landowners about the unwanted noise caused by vehicles traveling over rumble strips when they drift over the edge or centerline of the roadway. By changing and modifying the design, the ultimate goal is to provide the maximum safety by capturing the drivers attention through in-vehicle generated sound levels while minimizing the associated external noise generated by the rumble strips. Tests on TH 18 were performed with three different vehicles passenger car, pickup truck and a class 35 tandem dump truck. A single speed of 60 mph was used, as this was shown to provide the most meaningful data in the previous study. For each of the designs, an initial test was performed with vehicles traveling on normal pavement, followed by three passes on the rumble strip. Rumble strip designs 1 and 4 created lower exterior sound level increases but created interior levels similar to designs 2 and 3. The external results correspond to the depth of the rumble strip design, with designs 1 and 4 having a maximum depth of 1/8 inch less than designs 2 and 3. The interior sound level increases are similar for all four designs but vary by vehicle type. All of the designs created increases greater than 10 dBA for the passenger car, which is a desirable level for gaining attention of the driver. For the pickup truck, the interior sound level increases ranged from 4.5 to 6.8 dBA, while the increases for the dump truck ranged from 0.8 to 2.7 dBA.