ÅDT

ÅDT is a traffic-volume metric used in Norway and other Nordic countries. The acronym comes from Norwegian Årsdøgntrafikk, and it is commonly translated as Annual Average Daily Traffic. It represents the average number of vehicles that pass a reference point on a road during a calendar year.

Calculation and data sources: Data are collected from traffic counting devices such as inductive loops, pneumatic tubes, or GPS-based sources. The annual count is summed over all calendar days, and the result is divided by the number of days in the year (365 or 366). In practice, days with missing data are addressed through imputation or exclusion, and sometimes daily counts are weighted to reflect typical patterns, holidays, or seasonal variations.

Applications: ÅDT is used in road planning, capacity analysis, and design standards. It serves as a baseline for comparing road segments, prioritizing maintenance, and informing funding decisions. It also supports models that estimate emissions, noise, or safety effects associated with traffic.

Relation to other metrics: ÅDT is equivalent to the English term AADT (Annual Average Daily Traffic). It differs from peak-hour traffic or average weekday traffic, which describe different moments or subsets of traffic demand.

Limitations: As an annual average, ÅDT smooths out daily and hourly fluctuations and may not reflect peak demand or seasonal variations. The accuracy of ÅDT depends on data quality, coverage, and the methods used to handle missing data or irregular counting periods. See also AADT, traffic volume, and traffic engineering.