Historic Road Speeds

Data collected from vehicles on the move as GPS points; then this data is collated into a sufficiently large database, the points can be applied to the nearest piece of road and linked together to infer the average speed on that stretch of road (often further broken down by time of day and vehicle type, provided that the GPS location is tagged with this information). Applying historic road speed data to a digital road network in a GIS enables users to create realistic (based on averaged historic data) drive-time isochrones.