The Minnesota Road Research Facility (also known as Mn/ROAD, pronounced Min-road), is an outdoor research laboratory operated by the Minnesota Department of Transportation (Mn/DOT) that specializes in testing different types of pavement. Said to be the largest such facility in the world, it is located 40 miles (64 km) northwest of Minneapolis-St. Paul near the town of Albertville along Interstate 94 (I-94). Minnesota is a good site for such a project, as the state experiences some of the largest seasonal swings in temperature in the United States, and has a spring freeze–thaw cycle that can heavily damage roadways. More than 4,500 sensors are embedded in and under the road surfaces to measure stresses while the test segments are in use.