|Buckinghamshire • Middlesex|
The M4 Motorway was built through here in the 1960s. The M25 was constructed in the 1980s, opening to traffic in 1985. The connecting roads did not open immediately, but were completed a few months later.
In order to construct the interchange the main carriagesways of the M4 were diverted either side of the central core of the interchange in order to allow construction of the bridge carrying the M4 over the M25 to M4 slip roads, as well as the bridge carrying the M25 over the M4, and the high level bridges carrying M4 to M25 traffic. In addition, the whole interchange also bridges over a railway line.
As part of the interchange construction, the M4 was widened to the east to Junction 4.
|The WEST, Slough, Reading|
|London (W & C), Heathrow Airport (Terminals 1, 2 & 3), Central London, Hammersmith|
|(M40, M1, M11), Oxford, Watford, Stansted Airport|
|Heathrow Airport (Terminals 4, 5 & Cargo), (M3, M23, M20), Gatwick Airport, Dartford|