Friction Measurement System for Polk County
Lee Alexander, Rajesh Rajamani
Report no. MnDOT 2013-26
A friction measurement system was developed for Polk County and installed on two snowplows in the county's winter road-maintenance fleet. The major components of the developed system were a special instrumented wheel, a pneumatic pressure-controlled cylinder, force-measurement load cell and accelerometers, a data collection microprocessor and a data processing micro-processor. The road friction coefficient was estimated in real-time and was stored on a secure digital card along with the current GPS-sensed location of the truck. The friction coefficient information was also displayed in real-time using LED lights for the operator. Although the basic design of the friction wheel system had been used for several previous years of intermitant testing without showing significant wear, the almost identical installations on the Polk County trucks suffered bearing failures after the first few days of continuous use. The failed bearings were replaced with larger bearings in a more robust mount. Apparently, the system again failed in a few days, but the research team did not learn of this failure until the end of the project. The low budget for the project and the significant travel required to go to Crookston posed major challenges in getting a friction measurement to work effectively for Polk County.