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This Rumble Strip Noise Evaluation study presents results of sound level monitoring of three types of longitudinal rumble strips installed along the edge of two-lane rural roads in Polk County, Minnesota. The 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 driver's attention through tactile and sound levels while minimizing the associated external noise generated by the rumble strips. Both exterior and vehicle interior sound levels were measured from three longitudinal edge of pavement rumble strip designs - California, Pennsylvania and Minnesota. Simultaneous digital audio files were also recorded. Three vehicles were used - a passenger car, pickup, and semi-trailer truck. Tests were performed at 30, 45 and 60 mph. Comparison of exterior and interior sound levels and audio shows that the Pennsylvania design is the quietest, both interior and exterior. The interior level of the Minnesota and California designs are similar but exterior levels are higher for the Minnesota design.

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.

In this project, researchers studied the flow of freight in the 12-county northwestern region of Minnesota for the Minnesota Department of Transportation (Mn/DOT). This project uses data from C.J. Peterson & Associates, as well as data on agricultural commodities, timber, and Canadian border crossings. This report identifies major commodity flows by origin and destination within and outside of the region and assigns these to a regional highway network using the QRSII model. It presents annual flows by major commodity classification on each highway link, both in weight value shipped, which permits an identification of significant freight corridors within the region. Mn/DOT plans to use this information in targeting investment and maintenance of the region's transportation infrastructure. The study also serves as a prototype for examining freight flows in other regions of the state.

Extensive transportation systems, which include highways, rivers, Great Lakes ports, railroads, airports, and pipelines, link Minnesota to markets throughout the North American Continent. This study provides a comprehensive source of freight flow information in Minnesota and shows the ways in which the transportation systems support business and commerce. It draws upon data and analysis developed over the past five years with contributions from the University of Minnesota's Center for Transportation Studies and the Minnesota Department of Transportation. The report summarizes the freight flows in, out, through, and within Minnesota in 1990 by model and in some cases by major commodity and major origin or destination.