What it means: the length of the road network each year. New roads add only a few miles a year now; much recent motorway work has widened existing roads or turned the hard shoulder into a running lane, which adds capacity but not length. Minor roads grow as housing estates are built. Changes in how roads are measured, most recently in 2022, mean small year-to-year changes are not all new building. Shown for context.

Source: DfT, road length statistics, table RDL0103.