AADT or AADF - Annual Average Daily TrafficAADF / AADT – Annual Average Daily Traffic Flow


This is either known as AADF or AADT – Annual Average Daily Flow or Annual Average Daily Traffic. Essentially they are one and the same.  The government has now opted for AADF and has produced a website relating to annual traffic in the UK. Click here to go to their website.

Annual average daily traffic flow (AADT or AADF) is the total volume of vehicle traffic on a highway or road for a year divided by 365 days. AADT is a useful and simple measurement of how busy a road is. The AADT or AADF traffic data can be used for:

  • selecting a new site or business location
  • evaluating a site for development
  • determining funding for highway maintenance and improvement
  • forecasting road maintenance needs and expenditure
  • identifying the best location for your business based on traffic patterns
  • analysing the environmental hazards of pollution related to road transport

This is usually used by Highways departments of the local authority and Highways England, Scotland etc.

Similar surveys are AAWT – Annual Average Weekday Traffic which measures as above, but just on weekdays ignoring any bank holidays and ASDT – Average Summer Daily Traffic. This is a similar measure to the annual average daily traffic, however the ASDT data is collected during summer only. The measure is useful in areas where there are significant seasonal traffic volumes carried by a given road.


Page Updated:  26th June 2022