Thursday, 29 December 2011

UK Road Numbering System

Ever wonder about the logic behind the country's road numbering system? The system was developed in the 1920's as motor vehicle use increased. In England & Wales six routes radiating clockwise from London were identified:

A1 to Edinburgh
A2 to Dover
A3 to Portsmouth
A4 to Bristol
A5 to Holyhead
A6 to Carlisle

These routes created six sectors eg sector 1 was the area between the A1 & A2. Any road starting in this area was named A1x, A1xx or A1xxx the longer numbers been generally more minor roads. B roads are local routes. Roads crossing sectors will use the lowest sector number.

Similarly Scotland has four routes from Edinburgh giving 4 sectors.

A1 to London
A7 to Carlisle
A8 to Glasgow, Greenock
A9 to Thurso

The system is pretty consistent but there are anomalies. There two roads called A594. One is the Leicester inner ring road and the other runs from Maryport to Cockermouth in Cumbria.

Then there's the Motorways........

UK road sectors

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