|Via:||Uxbridge, Beaconsfield, High Wycombe, Oxford, Gloucester, Abergavenny, Carmarthen|
|Distance:||263 miles (423.2 km)|
|Meets:||M5, M40, A1, A4, A5, A38, A44, A48, A46, A48, A49, A312, A329, A355, A361, A404, A406, A412, A413, A415, A417, A418, A420, A429, A435, A436, A437, A449, A465, A466, A470, A477, A478, A479, A482, A483, A484, A485, A487|
|Former Number(s):||A40(M), A48|
Highways England • North and Mid Wales Trunk Road Agent • South Wales Trunk Road Agent • Transport for London • Buckinghamshire • City of London • Gloucestershire • Herefordshire • Islington • Oxfordshire • Westminster
|Route outline (key)|
The A40 is a major road that runs between London and Fishguard. Going via Oxford and Gloucester it is a road of varying degrees of standard from ex motorway to S2. At a distance of 263 miles it makes the A40 Britain's 7th longest road.
See Route Sections: Central London - Denham • Denham - Wheatley • Wheatley - Witney • Witney - Cheltenham • Cheltenham - Ross • Ross - Abergavenny • Abergavenny - Brecon • Brecon - Carmarthen • Carmarthen - Haverfordwest • Haverfordwest - Fishguard
As with many of the long A-roads, the A40 has had a vast array of upgrades over the years. Some major, others not so major. However the section from Denham to Oxford Services was mostly replaced by the M40 therefore this section has had very few changes.
Notable locations and improvements
Holborn Viaduct is the city of London's only bridge wholly within the square mile. Built in 1869, it allows the A40 to cross the A201. The lost River Fleet is underneath the A201.
The Denham Roundabout is where the A40 become M40. It is where the A40 loses it trunk status until Oxford services
Golden Valley Junction
The Golden Valley junction is where the A40 meets the M5. It is one of the busiest junctions found on the M5 therefore a important one.
|2000||Westway||Road downgraded from Motorway to A40.|
|1960s||Gibraltar Tunnels||Tunnel south of Monmouth.|
|1869||Holborn Viaduct||Bridge over the A201.|
- The A40 Trunk Road (M5 Motorway Junction 11 to the Gloucestershire/Oxfordshire County Boundary) (Detrunking) Order 2005
- The A40 Trunk Road (Wolvercote Roundabout Oxford to the Oxfordshire/Gloucestershire County Boundary) (Detrunking) Order 2003