ASDT - Average summer daily trafficASDT – Average Summer Daily Traffic


Average summer daily traffic (ASDT) is the total volume of vehicle traffic, seven days a week in the summer, on a road or motorway for a year divided by the number days in the summer. ASDT is a useful and simple measurement of how busy a road is during the summer season. The ASDT 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 AADT – Annual Average DailyTraffic which measures as above, but on all days of the year and AAWT – Annual Average Weekday Traffic – ignoring weekends and bank holidays.