A40 road

A40 road
Country	England
Route	40
Length mi	174
Terminus a	City of London
Terminus b	M48 near Monmouth
Regions	Greater London, Oxfordshire, Gloucestershire, Monmouthshire
Established	1923

A40 road

The A40 road is a major trunk route linking central London with the Severn Estuary and the Wales border, running through historic and commercial centres such as City of London, Westminster, Kensington, Shepherd's Bush, Ealing, Oxford, Cheltenham, and Gloucester. Originating near St Mary-le-Bow and terminating at the M48 motorway near Monmouth, the road connects urban districts, market towns, university cities, and port approaches while intersecting strategic routes including the M25 motorway, M40 motorway, and M4 motorway. Its alignment reflects successive phases of turnpike, coaching, and modern road planning that shaped south-central and south-west England.

Route

The route begins in the City of London near Cheapside and proceeds westward through St Martin-in-the-Fields adjacent to Whitehall, passing Notting Hill and Holland Park before reaching the western suburbs of Ealing and Southall. Beyond Uxbridge Road, the road joins or parallels the M40 motorway corridor around Beaconsfield and continues through the Cotswolds, traversing the market town of Burford and approaching the university city of Oxford via the A420 road junction at Botley Road. From Oxford it proceeds west past Faringdon and Lechlade into Gloucestershire, running near Cheltenham Spa and converging with the A417 road near Cirencester and Gloucester where it meets the M5 motorway interchange at Junction 11. West of Gloucester the A40 follows the Wye Valley corridor, skirting Ross-on-Wye before crossing into Monmouthshire to join the M48 motorway close to Chepstow and Monmouth.

History

The road overlays ancient tracks and Roman alignments connecting Londinium with western settlements and estuarine crossings. In the 18th century sections were improved under turnpike trusts established by Acts of Parliament in counties including Oxfordshire, Gloucestershire, and Middlesex. During the coaching era the route served stagecoaches between London and Bath, Bristol, and Chepstow, linking inns such as those recorded in travelogues by Daniel Defoe and John Wesley. The 20th-century classification system of 1923 assigned the A40 number as part of a national scheme alongside routes like A1 road and A4 road, with subsequent interwar and postwar upgrades introducing bypasses at Cheltenham and Burford and dual-carriageway sections constructed in the 1960s and 1970s contemporaneously with the development of the M40 motorway and M4 motorway. Late 20th-century projects included interchange remodelling near Oxford and relief schemes around Ross-on-Wye influenced by environmental legislation such as the Town and Country Planning Act 1990 and conservation designations like the Cotswolds Area of Outstanding Natural Beauty.

Major junctions and connections

The A40 intersects numerous principal highways and nodes: in London it links to the A201 road and access roads serving Hyde Park Corner and Marble Arch; near M25 motorway it connects to orbital networks and freight corridors serving Heathrow Airport via the A4 road; further west the A40 forms a strategic link to the M40 motorway at interchanges near High Wycombe and Stokenchurch for long-distance traffic toward Birmingham and the West Midlands. At Oxford it meets radial A-roads including the A34 road and A420 road which provide routes to Bicester and Swindon respectively. In Gloucester the A40 provides interchange with the M5 motorway and freight routes to Port of Bristol via the A38 road. Westward junctions with the A449 road and A48 road facilitate access to Newport and Cardiff regions, while the connection to the M48 motorway serves crossings of the Severn Bridge and approaches to Chepstow.

Traffic, usage and safety

Traffic volumes vary from dense urban flows in Westminster and Ealing to moderate interurban volumes across the Cotswolds and rural corridors near Ross-on-Wye. Peak-hour congestion is frequent in sections approaching Central London and the Portland Road–Notting Hill corridor, with heavy goods vehicles using the A40 as an alternative to the M4 motorway when accessing Bristol and South Wales freight terminals. Safety records show clusters of collisions at complex junctions such as the A4320 interchange near Oxford and rural bends in Gloucestershire; transport authorities including National Highways and local councils have published casualty reduction strategies under statutory frameworks like the Road Traffic Act 1988.

Public transport and cycling provision

The corridor supports commuter and interurban bus services operated by companies including Stagecoach Group, Arriva, and regional operators linking London with Oxford and Cheltenham, while local bus networks serve suburban hubs like Ealing Broadway and Hammersmith. Park-and-ride sites near Oxford and Cheltenham integrate with the A40 corridor to reduce inner-city pressure. Cycling provision varies: segregated cycleways and Quietways in West London connect to the A40 corridor via junctions near Shepherd's Bush and Acton, while rural stretches feature National Cycle Network routes managed by Sustrans with advisory signage and selective hard shoulders.

Future developments and improvements

Planned schemes focus on junction upgrades, safety improvements, and environmental mitigation. Proposals promoted by county councils and combined authorities include coordinated junction remodelling near Eynsham to improve access to Oxford, carriageway resurfacing programmes in Gloucestershire, and active travel enhancements influenced by Cycling and Walking Investment Strategy funding. Strategic resilience measures consider climate impacts on low-lying crossings near the Severn Estuary, and proposals to manage freight routing are aligned with rail freight terminals such as Didcot Parkway and logistics hubs in Thames Gateway.

Category:Roads in England Category:Transport in London Category:Transport in Gloucestershire