The road, air, rail, and water networks facilitate transport in the United Kingdom. There are 29,145 miles (46,904 kilometers) of main roads, 2,173 miles (3,497 kilometers) of motorways, and 213,750 miles (344,000 kilometers) of paved roads in a radial road network. Over 18,000 passenger and 1,000 freight trains travel daily on the National Rail network, which spans 10,072 route miles (16,116 km) in Great Britain and 189 route miles (303 route km) in Northern Ireland. Belfast, Birmingham, Cardiff, Edinburgh, Glasgow, Liverpool, London, Manchester, and Newcastle all have urban rail networks. There are numerous regional and international airports, including London's Heathrow Airport, which ranks among the top ten busiest in the world. Additionally, the United Kingdom has a system of ports that handled over 486 million tons of goods in 2019. The United Kingdom's largest contributor to greenhouse gas emissions is transportation.
The United Kingdom has seen an increase in car use, which has increased its modal share, since 1952 (the earliest date for which comparable figures are available), while bus use has decreased and railway use has grown more slowly. However, from 5% to 10% of passenger-kilometers traveled in the 1990s, rail has started increasing its modal share at the expense of cars. The impact of this, which occurred concurrently with British Rail's privatization, is hotly debated. In 1952, cars and taxis accounted for 27% of travel distance; with 18% traveling by train and 42% by bus or coach. Additionally, 11% and 3% traveled by motorcycle and bicycle. The flight distance was insignificant.