Since the publication of the 2016 road traffic statistics on Thursday 27 April 2017, a minor formatting error has been discovered affecting table TRA4201. This table has now been corrected, and no other tables were affected by this revision.
DfT road traffic statistics team are conducting a review of the traffic estimates for Great Britain. The aim of the review is to ensure robust traffic estimates continue to be produced, seeking innovation and greater value for money in their production while protecting user needs. The review is due to be completed in 2016.
Provisional traffic estimates are based on traffic data collected continuously from a national network of around 180 Automatic Traffic Counters (ATC).
Provisional estimates are published quarterly and remain provisional until they have been constrained by the final annual estimates each year.
Final annual road traffic estimates are mainly based on around ten thousand manual counts, which are combined with ATC data and road lengths to produce overall estimates.
Traffic estimates for major roads are based on a census whereas traffic estimates for minor roads are estimated by calculating growth rates from a fixed sample of count points on the minor road network.