Accident Analysis of Significant Crash Rates for Low to Very Low Volume Roadways in 10 Minnesota Counties


Michael Wade, Curtis Hammond, Kim ChungGon

March 2004

Report no. Mn/DOT 2004-22

Three sets of analysis were carried out on the database. First was a descriptive analysis of the data to determine the general frequency rates of accidents. A second identified dangerous roadways. Counting the number of crashes on specific roadways and dividing this number by the average ADT on a roadway generated crash rates for those roadways, including county state aid highways (CSAHs), county highways, and township roads. Roadways with the highest five percent were considered significantly dangerous. Crash rates were generated for specific locations. This method identified 15 dangerous locations, nine on CSAHs, three on county highways, and two on township roads. There were only 235 cases where no improper driving was indicated. The remaining 1,554 cases suggested that driver error was the major cause. The most likely factor in causing an accident on a highway with an ADT of less than 400 is a crash involving an animal. Road design factors such as number of lanes and the speed limit seem to be the factors related to these accidents.

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