The United Kingdom
's roads are arranged radially around London
s with single-digit numbers form the main arteries:
- The A1 is the Great North Road from London to Edinburgh along the east coast.
- The A2 runs south-east from London to the channel ports.
- The A3 runs more or less south from London.
- The A4 is the main road west from London towards Bath.
- The A5 is Watling Street, the main road north-west from London to Holyhead.
- The A6 is the road to Carlisle.
- The A7 is the continuation of the A6 north to Edinburgh.
- The A8 runs west from Edinburgh to Glasgow and thence to Greenock.
- The A9 leads north from Edinburgh to Scrabster, near Thurso.
Roads on the clockwise side of a main A-road have two, three and four digit numbers beginning with the appropriate digit, so that near the A1 you find the A10
, the A1000
and the A11
. Between the A1 and the A7 in Scotland
, the roads are treated as being clockwise of the A6.
B-roads are more minor, and similarly grouped. Motorways are usually numbered to match nearby A-roads, which leads to incongrous results as the motorways are extended.
Twinned with How the United States Highway System Works