What it means: the total distance driven by all motor vehicles on public roads in a year, stacked by type of vehicle. Traffic grew almost every year from 1949, dipped after the 2008 financial crisis and fell sharply in 2020. Van traffic has grown fastest, with online shopping and deliveries. Miles driven matter for congestion, road safety and emissions, but more or less driving is not good or bad in itself, so this is shown for context.

Source: DfT, road traffic estimates, table TRA0101.