Studded tire research in Norway, Finland and Sweden

In June of 1995, engineers for the Alaska Department of Transportation and Public Facilities journeyed to Norway, Sweden and Finland to investigate Scandinavian research into reducing the effects of studded tires on pavements. Many northern tier states in the United States have banned studded tires: since the 1970's. little research has been done in North America. The road administrations, road institutes, and tire manufacturers of Norway, Sweden and Finland have continued to do extensive research on studded tires. To solve the problem of stud damage 10 pavements the three countries researched stud design, tire traction, driver behavior, aggregates, asphalt concrete, and asphalt mix designs. The solution to studded tire wear involved a three pronged approach. First, the countries legislated the use of lightweight studs: studs that weigh less than 1.1 grams. The core of the stud is tungsten carbide steel, but the lightweight sleeve is either plastic or aluminum oxide. This stud reduced pavement wear rates by 50 percent. Second, they used a Stone Mastic Asphalt (SMA) concrete mis ibr surface courses. This mix contains up in 70 percent coarse aggregate. The use of SMA can reduce pavement wear rates from 25 to 50 percent. Third, they found hard durable aggregates that resist studded tire wear better than aggregates from local material sources. They developed tests such as the Brill Mill Test, SRK Test and the Point Load Test. Their research showed that the commonly used wear and degradation tests do not correlate to pavement wear due to studded tires. The harder aggregates that resist studded tire wear are fine grained metamorphic and volcanic rocks and make up only 2 to 4 percent of the rock in Scandinavia. They have hauled this rock up to 300 kilometers for a wearing course. The use of these harder aggregates can reduce wear rates by a factor of three to five compared to using local aggregates.