Investigation of Winter-Weather Speed Variability in Sport Utility Vehicles, Pickup Trucks, and Passenger Cars

Abstract

The different characteristics of sport utility vehicles (SUVs), pickup trucks, and passenger cars put the smaller vehicle at a disadvantage in a crash. A larger difference in the speed of two vehicles can also increase crash severity, and increases in speed variability on a roadway can decrease overall safety. Research investigated whether drivers of SUVs, pickup trucks, and passenger cars choose different vehicle speeds during winter weather. Vehicle speed, roadway condition, time of day, and vehicle type were recorded during normal and winter-weather conditions. The results indicated that winter-weather vehicle speeds for all three vehicle types were significantly less than normal and that during the day a large percentage of the speed reduction occurs after snow begins to accumulate in the gutter pans of the roadway. Vehicle speed variability also increases during winter-weather conditions. The average SUV speed was statistically higher than the average passenger car speed during the day for four of the five winter-weather roadway surface conditions observed. The magnitude of the speed differences increased with roadway snowcover, but it was always less than 5.6 km/h (3.5 mph). The winter-weather speed differences between passenger cars and SUVs, although small, may have safety implications. The safety of winter-weather roadways may be lower than before the increase in SUV use, more-severe winter-weather crashes may occur between passenger cars and SUVs, more SUV run-off-the-road crashes might occur, and the safety benefits of larger vehicle characteristics may be smaller than believed.