Understanding speed & navigation data for GIS
Creating drive-time catchments and calculating travel times to specific points are key to setting customer service targets, depot territory management, site location analysis, network planning, vehicle scheduling and gravity modelling.
A range of datasets are currently available as vector or link and node networks with speeds attached. The speeds provided with the standard AA data reflect the DfT road classification (A road, B road etc.) with reduced speeds in urban areas. NAVTEQ provides further refinements with more specific speed categories. For example, at Hangar Lane in west London the roundabout portion of the A406 is slower than the main road.
Most speed information is provided as off-peak travel times, but MapMechanics has worked together with traffic information specialists INRIX (formerly ITIS) to establish the relative congestion both regionally and by the time of day. This attribute data is provided with the AA 1:200,000 vector routing network, OS ITN or NAVTEQ road and street data. It has been created from information derived from billions of GPS signals from vehicles on the move throughout the UK.
The Speeds and Speeds Plus products provide different values on each link according to actual speeds recorded at different times of day.
Navigational data includes on the ground information such as banned turns, one-way systems, low bridges, traffic volumes, specialist data such as Hazmat restrictions, etc.