Using Probe-Car Data to Analyze Winter Road Traffic Performance in the Urban Sapporo Area

Annual snowfall is 5 meters in Sapporo City, Hokkaido Prefecture of Japan, and winter traffic congestion causes great economic losses in the greater Sapporo area. In partnership with a taxi company that operates 115 GPS-equipped vehicles whose aggregate daily travel distance is approximately 40,000 km, a probe car survey was conducted using taxi probe-car data of time of day, coordinates (latitude and longitude), and speed, recorded at regular intervals. The authors analyze winter road traffic performance in terms of average travel speeds using the taxi probe-car data, and discuss the quality of service required by road users in Sapporo City. It is found that vehicle travel speeds are reduced in winter by snowfall and by icy or compacted-snow road surface conditions.