Roger and Philip Tagg's

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Look up an A-road number

1. Click the map region (→↘) corresponding to the first digit of the A-road whose trajectory you want to display, e.g. 9 for A9, A92 or A971; or 5 for the A5, A59 or A505

2. In the actual listing shown after clicking a map region, either: [a] scroll down to the A-road number you're looking for; or [b] click the nearest multiple of 25 to the number you want (e.g. 350 for the A361); or [c] use your browser's Find function (Ctrl-F in Windows) and just enter the number you want.

3. If you need more detail about your A-road, visit the Wikipediia list online.


Coverage. The listings cover 1, 2 and 3-digit
A-roads in GB, i.e. England, Wales and Scotland, incl. Orkney and Shetland, but not the Channel Islands, the Isle of Man or Northern Ireland where other numbering systems apply.

Numbering system. A-roads (B-roads too, incidentally) are numbered in a clockwise system defined by radials of the single-digit A-roads starting in London (A1-A6) or Edinburgh (A7-A9). A-roads starting in, say, region 4 either run entirely in region 4 (e.g. A44 from Oxford to Aberystwyth) or they cross one or more main radials in a clockwise direction. For example, the A46 from Bath via Coventry, Leicester and Lincoln to the North Sea at Cleethorpes, crosses the A5, A6 and A1 to end in '1' territory. But A-roads starting with 4 cannot run into the threes or twos, and those starting with a 3 cannot run anticlockwise into territory 2. In short, the A38 can cross radials clockwise into territories 4, 5 and 6; the A52 can run from region 5 into regions 6 and 1, the A63 from 6 into 1, the A73 from 7 into 8 and so on, but the A66 cannot run into region 5 or less. Only trouble is that the A66 and several others disobey the rule (Dissolution).

Anomalies. The most radical exceptions to the numbering rules just explained are those described under Dissolution. Other anomalies are of lesser import, for example: [1] the bit of Kent between the A2 and the Thames estuary is not territory 1 (anti-clockwise from region 2) but region 2 (e.g. A28, A249-50, A298, A299), the only A100s to enter this territory being those to cross the estuary from north to south (A100, A101, A102); [2] though most A-roads in Scotland start with 7, 8 or 9, several in the southeastern borders start with 6 (A68, A697-A699), and a few with 1 between the A1 and the North Sea (A198, A199).

Dissolution of numbering system. The numbering system explained above has been slowly dissolving since the construction of Britain's motorway network. This process has two very noticeable effects. [1] Several A-roads are now rerouted to be carried by motorways or by other recently constructed or upgraded main roads: the A41, for example, spends much of its time unidentified on the M40 and M42 . [2] New cross-country numbering breaks the clockwise rule so that, for example, the new A14 (from 1992) 'illegally' crosses radials anticlockwise from territory 1 to 6 (near Huntingdon) and from 6 to 5 (at Kettering). Similarly, the A66, 'correctly' extended into region 1, now also runs 'incorrectly' into region 5. The whole idea is to give important, newly upgraded roads that cross the country a single identity and a two-digit A-road number.

Find A-roads from place names

Sorry. This routine is not yet available but it is possible (and fast) to use your browser's Find function in the actual listing.

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© info: British A-road Listings by Roger M Tagg & Philip D Tagg is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Permissions beyond the scope of this license may be available at Roger M Tagg and Philip D Tagg, 2010.