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The risk of fatal road accidents in winter between studded and unstudded tires does not differ significantly. However, the accident risk has recently been substantially higher on bald ice for unstudded than for studded tires. The magnitude of this risk difference is difficult to determine without specific information on exposure by road surface.

Purpose This field study was designed to compare to what degree various proportions of studded and unstudded winter tyres affect the roughness and polishing of road surfaces covered with ice and compact snow. Methods Test cars equipped with studded and unstudded winter tyres drove around a test track according to the designed procedure. The main straight section of the track had five lanes, each with a different proportion of cars with studded tyres: 100%, 75%, 50%, 25% and 0% of the respective lane traffic. The remainder were cars with unstudded winter tyres. Each lane included sections of ice and compact snow with subsections for constant speed, braking and acceleration. The lanes were driven 642 times. The ambient temperature was approximately 0°C during the test. Results The overall results showed that there was no substantial difference in friction of the road surface between lanes having 100%, 75% or 50% of cars with studded tyres. However, the friction was much poorer in lanes having fewer cars with studded tyres. Conclusions These results suggest that traffic with 50% of cars having studded tyres results in adequate friction of icy road surfaces in the test conditions.

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or several years, the U.S. Federal Highway Administration (FHWA) Office of Transportation Operations Road Weather Management Program has been involved in the development of a guidance tool for winter road maintenance decision makers. The tool, known as the maintenance decision support system (MDSS), is the culmination of work by a consortium of national laboratories, directed by FHWA with feedback from both the state departments of transportation and the private sector. The MDSS combines advanced weather and road condition prediction with automated rules of practice to produce a customized and optimized set of treatment recommendations for winter road maintenance managers. The potential payoff is higher mobility and safety on roadways, and more efficient and cost-effective use of staff, equipment, and chemicals. The latter would produce a reduced impact on the environment. This paper describes the history, development, and status of the MDSS project. Preliminary results and lessons learned from a field demonstration, future development efforts, and the technology transfer plan is discussed.