The volume of transport output is measured in miles travelled by parties of individuals. The source of information for this estimate is the National Travel Survey (NTS). We have used information collected on the purpose and method of travel, the length of trip and numbers in parties, and whether the respondents live in London or in the rest of the UK. Walking for pleasure or exercise has been excluded. The NTS samples all households in Great Britain, and the survey estimates have been grossed to the UK population using data derived from the Labour Force Survey, which exclude people living in institutions.

For further details, see Chapter 3 of the HHSA Methodology (downloads).

See Value for prices and value estimates.