M40 motorway

The M40 motorway links London, Oxford, and Birmingham in England, a distance of approximately 89 miles (143 km).

The motorway is dual three lanes except for junction 1A to junction 3 (which is dual four lanes) a short section in-between the exit and entry slip-roads at junction 4 (which is two lanes in both directions) and also between the slip-roads at junction 9 (in the south-eastbound direction only).

An Active Traffic Management system operates on the short section north-westbound from junction 16 (A3400) to the M42.

The motorway between London and Oxford was constructed in stages between 1967 and 1974. The first section opened in June 1967, from Handy Cross roundabout, High Wycombe to Stokenchurch (junctions 4–5). In 1969, extending in a southerly direction to Holtspur, Beaconsfield, a temporary junction 2 was opened. The section bypassing Beaconsfield was built in 1971 and the section past Gerrards Cross to junction 1 was completed in 1973. In 1974, the motorway between junctions 5 to 8 was completed to Great Milton.

Between junctions 3 and 4, the beginnings of slip roads were built on both carriageways for a service area at Abbey Barns between Beaconsfield and High Wycombe. Beaconsfield services off junction 2 opened in 2009.

Late in the 1960s, not long after the first stretch opened, the Ministry of Transport announced the possibility of building a new motorway to link London with Birmingham as an alternative to the M1–M6 route – as well as improving road links to the South Coast ports for The Midlands – but it was not until 1983 that the decision to extend the M40 from Oxford to the south of Birmingham was made.

The preferred route was altered to avoid Otmoor after a vigorous road protest, which included selling over 3,000 small squares of a field to people all over the world. The field had been renamed 'Alice's field' as a reference to Alice in Wonderland by Lewis Carroll who lived in the area at the time of the book's writing.

Construction began at Warwick in October 1987, with work on the section around Banbury starting in February 1988, and finally, the section north of Oxford in July 1989. The section between the M42 and Warwick opened in December 1989, and the remainder in January 1991.