List of motorways in the United Kingdom
The list of motorways in the United Kingdom is a complete list of motorways in the United Kingdom. Note that the numbering scheme used for Great Britain does not include roads in Northern Ireland, which are allocated numbers on an ad hoc basis.
Great Britain
M-designated motorways
Upgraded A-road designations
Former motorways
Roads which used to be motorways but have been downgraded:| Link | Description |
| M10 | A short spur linking St Albans to the M1 near Hemel Hempstead. Now part of the A414. |
| M15 | The designation for the Ringway 2 upgrade of the A406 and A205. Only the section between junction 4 of the M11 and Redbridge Roundabout was built to motorway standard and was initially signed as M11 because the section built, at the time, only led to and from the M11. When the route was extended to Beckton, this section of M11 was redesignated as the A406. |
| M41 | The London West Cross Route, a spur from the London Westway and the only part of the western section of the London Motorway Box to be built, now A3220. |
| A18 | A spur from M18. Mostly now part of M180, although a section has been abandoned. |
| A36 | The Ower Spur, now the A36. |
| A40 | The London Westway, now the A40. |
| A41 | The Tring bypass, now the A41. |
| A46 | A spur towards Leicester from M1 at junction 21, now part of the A5460. |
| A102 | The London East Cross Route, in two sections:
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| A329 | The northern third of the A329 from Winnersh to Reading, now the A3290. Downgraded to permit Reading council to dedicate one lane for buses. |
| A6144 | Formerly the longest single-carriageway motorway spur in the United Kingdom from the M60 north of Sale towards Carrington. Now just a spur of the A6144. |
Motorways that have been renumbered
Motorways under construction or planned
The Adwick-le-Street to M62 stretch of the A1 is under consideration for upgrade to motorway standard, meaning the A1 between Blyth, south of Doncaster, to Birtley near Gateshead, would all be part of the same A1 stretch of motorway.In addition, the proposal to put a tunnel under the River Thames to the east of Dartford Crossing and the revived Birmingham Western Orbital plans are both described as motorways.
Unbuilt motorways
There have been many plans for motorways in the UK that have not been built. Below is a list of plans that were not built :- M12 in 3 forms :
- * From the London end of the M11 to Brentwood;
- * From the London end of the M11 to Maplin Sands Airport ;
- * From the M25 to Chelmsford.
- M13, from East London to Maplin Sands airport passing south of Southend.
- M17 Castle Donington bypass, a short spur off the M1;
- M31, a bypass of the busiest section of the M25, cutting the corner for traffic from the west. Partially built as the A329 and A3290.
- M59, M58 junction 2 to south of Preston.
- M64, between the M6 south of Stoke-on-Trent and the M1 near Derby. Mostly built as the A50.
- M601, which would have entered Manchester from the M62 in the Irwell Valley at Clifton near Pendlebury.
- M650, Airedale Motorway from near Silsden to Shipley.
- A6, which would have formed an eastern bypass for Stockport. As of March 2006, this is still under the planning stage as part of the SEMMMS project.
- A556, which would have cut the corner between the M6 and M56 near Warrington.
- Chippenham Spur, off the M4
- Strensham – Solihull motorway, a link between the M50 and M42 or M69
- Most of the M67 – from Hattersley to the M1 via the Hope Valley in the Peak District national park and Sheffield. Various routes have been proposed but have yet to come to fruition due to controversy and/or expense. In 2014, the then Sheffield Hallam MP and Deputy Prime Minister, Nick Clegg signalled his support for improvements to the Woodhead Pass. The latest proposal to extend the M67 is to tunnel under the Peak District from Hattersley to Stannington and to link that tunnel to a new underground motorway providing links to the M1.
It was proposed that the A14 upgrade between Huntingdon and Cambridge would be classified as a motorway once complete, however prior to opening it was announced that the road would open as a "best in class A road" instead.
Northern Ireland
M-designated motorways
Upgraded A-road designations
Unbuilt motorways
The following motorways were planned, but never built.- M11, from the M1 going through Lisburn and then crossing the M1 again and ending at Newry
- M23, from the M2 to Derry