Thorney Interchange from the south, looking north along the M25 in July 2009; it is junction 15 of the M25
|Type||4-level stack interchange|
|Constructed||by Cementation Company and Costain Group|
|Opened||19 December 1985|
|Maintained by||Highways England|
The Thorney Interchangeis a large motorway intersection in the UK, between the M4 and M25. It is one of the busiest motorway interchanges in the UK. It is situated directly on the edge of Buckinghamshire and Greater London (London Borough of Hillingdon).
Buckinghamshire, abbreviated Bucks, is a ceremonial county in South East England which borders Greater London to the south east, Berkshire to the south, Oxfordshire to the west, Northamptonshire to the north, Bedfordshire to the north east and Hertfordshire to the east.
Greater London is a ceremonial county of England that forms the London region. This region forms the administrative boundaries of London and is organised into 33 local government districts—the 32 London boroughs and the City of London, which is located within the region but is separate from the county. The Greater London Authority, based in Southwark, is responsible for strategic local government across the region and consists of the Mayor of London and the London Assembly. The City of London Corporation is the principal local authority for the City of London, with a similar role to that of the 32 London borough councils.
The London Borough of Hillingdon is a large borough located in Greater London, England which had a population of 273,936 according to the 2011 Census. It was formed from the districts of Hayes and Harlington, Ruislip-Northwood, Uxbridge, and Yiewsley and West Drayton in the county of Middlesex. Today, Hillingdon is home to Heathrow Airport and Brunel University, and is the second largest of the 32 London boroughs by area.
The M4 (London-South Wales Motorway) under the interchange was opened in December 1964, from junctions 4 (A408) to 5; this 3.9-mile section cost £3.2m, and was built by Cubitts and Green. The interchange, hence, is junction 4b of the M4.
Holland, Hannen & Cubitts was a major building firm responsible for many of the great buildings of London.
The interchange is around one mile north-west of Heathrow Airport; the interchange is the main junction for traffic heading from the M25 to the airport. The interchange is the point that the M4 enters Greater London.
Heathrow Airport, also known as London Heathrow, is a major international airport in London, United Kingdom. Heathrow is the second busiest airport in the world by international passenger traffic, as well as the busiest airport in Europe by passenger traffic, and the seventh busiest airport in the world by total passenger traffic. It is one of six international airports serving Greater London. In 2018, it handled a record 80.1 million passengers, a 2.7% increase from 2017 as well as 477,604 aircraft movements, an increase of 1,821 from 2017.
The bridge decks were to be built of prestressed concrete, but instead were built with composite steel beams and concrete decks, designed to BS 5400. In the early 1980s, when the interchange was being built, the entire M25 was to cost around £600m.
Prestressed concrete is a form of concrete used in construction. It is substantially "prestressed" (compressed) during its fabrication, in a manner that strengthens it against tensile forces which will exist when in service.
BS 5400 was a British Standard code of practice for the design and construction of steel, concrete and composite bridges. It was applicable to highway, railway and pedestrian bridges. It has now been replaced by the European standard, BS EN 1991-2_2003 and other Eurocodes for the design of steel and concrete structures.
The southern part of the M4/M25 interchange was part of a 2.05-mile section of the M25 which was due to open in spring 1985, the Poyle to Thorney Mill Road section, from junction 14 (Poyle Interchange) to junction 15. The £44m contract, given to the joint venture of Cementation/Costain, was to take three years.The M25 section was due to be open nine months before the M4/M25 interchange would open.
The northern section of the interchange was to be part of a 10.5-mile section of the M25 also due to open in spring 1985; this later became the 4-mile M4 to Iver Heath section to the M40, at Denham Interchange junction 16. The 6.5-mile section of the M25 directly north of the M40 opened in January 1985.
The M40 motorway links London, Oxford and Birmingham, a distance of approximately 89 miles (143 km).
Much of the M25 was designed by Halcrow Group. The interchange was designed by Atkins.
3.5m cubic metres of infill was needed for the contoured landscaping.
The section of M25 to the north began construction in April 1983.Construction took 28 months, and cost £25m, with £10m for the fifteen bridges, by Wimpey Construction. The bridges were built to allow expansion to four lanes at a later date. The M25 was opened by Nicholas Ridley, Baron Ridley of Liddesdale on Wednesday 18 September 1985, an 11-mile section directly south of the M40 to Poyle. The section had cost £80m. The M4/M25 junction was planned to open at a later date of June 1986, but it opened six months early, due to good weather, on Thursday 19 December 1985. At the time of opening two sections of the M25 remained – in Hertfordshire and Kent (which opened in February 1986), and the M4/M25 junction was expected to be the busiest motorway junction in the UK.
It is a typical stack interchange. The part of the interchange that is north of the M4 is in Iver, in South Bucks. It is named after Thorney, Buckinghamshire, now part of Iver, the village in which the northern part of the interchange in situated. The part of the interchange that is south of the M4 is in Colnbrook with Poyle, in Slough. West Drayton and Harmondsworth are close to the east.
There are 11 bridges and three major viaducts, varying from 182m to 264m long. A 229m viaduct carries the M25 over the M4.
A single-track disused railway line passes through the middle of the interchange. The railway line, the former Staines and West Drayton Railway, is still there.The railway line went from West Drayton railway station, to the north, to Staines West railway station, to the south, and the disused section passes through the Lakeside Road Industrial Estate to the south.
Colnbrook is a village in the unitary authority of Slough in Berkshire, England. It lies within the historic boundaries of Buckinghamshire, and straddles two distributaries of the Colne, the Colne Brook and Wraysbury River. These two streams have their confluence just to the southeast of the village. Colnbrook is centred 3 miles (4.8 km) southeast of Slough, 3.5 miles (5.6 km) east of Windsor, and 18 miles (29 km) west of central London.
The M1 motorway connects London to Leeds, where it joins the A1(M) near Aberford, to connect to Newcastle. It was the first inter-urban motorway to be completed in the UK; the first motorway in the country was the Preston By-pass, which later became part of the M6.
The M62 is a 107-mile-long (172 km) west–east trans-Pennine motorway in Northern England, connecting Liverpool and Hull via Manchester and Leeds; 7 miles (11 km) of the route is shared with the M60 orbital motorway around Manchester. The road is part of the unsigned Euroroutes E20 and E22.
The A38, part of which is also known as the Devon Expressway, is a major A-class trunk road in England.
The M5 is a motorway in England linking the Midlands and the South West. It runs from Junction 8 of the M6 at West Bromwich near Birmingham to Exeter in Devon. Heading south-west, the M5 runs east of West Bromwich and west of Birmingham through Sandwell Valley. It continues past Bromsgrove, Droitwich Spa, Worcester, Tewkesbury, Cheltenham, Gloucester, Bristol, Weston-super-Mare, Bridgwater and Taunton on its way to Exeter, ending at Junction 31. It is the primary gateway to South West England. Congestion is common during the summer holidays, on Friday afternoons, and school and bank holidays on the section south of the M4.
The M18 is a motorway in Yorkshire, England. It runs from the east of Rotherham to Goole and is approximately 26 miles (42 km) long. A section of the road forms part of the unsigned Euroroute E13.
The M20 is a motorway in Kent, England. It follows on from the A20 at Swanley, meeting the M25, and continuing on to Folkestone, providing a link to the Channel Tunnel and the ports at Dover. It is 50.6 miles (81.4 km) long. Although not signposted in England, this road is part of the European route E15.
The A14 is a trunk road in England, running 127 miles (204 km) from the Port of Felixstowe, Suffolk to its western end at the Catthorpe Interchange; a major intersection at the southern end of the M6 and junction 19 of the M1 in Leicestershire. The road forms part of the unsigned Euroroutes E24 and E30.
The M180 is a 25.5 miles (41.0 km) motorway in England from junction 5 on the M18 motorway in the Metropolitan Borough of Doncaster to a point close to Humberside Airport some 10 miles (16 km) from the port of Immingham and 14 miles (23 km) from the port of Grimsby and the east coast and provides access for major routes to Cleethorpes, Grimsby, Hull, Immingham, Lincoln, Scunthorpe, Humberside Airport and the Killingholme Oil Refineries; Humber Oil Refinery and Lindsey Oil Refinery. The road forms part of the unsigned Euroroute E22 and is the main route along the south bank of the Humber Estuary. At 25 miles long it is the longest motorway in the United Kingdom to carry a three digit number.
The M50 is a 22-mile/35-km-long dual two-lane motorway in Worcestershire, Gloucestershire, and Herefordshire, England. It is sometimes referred to as the Ross Spur, connecting, as it does, the M5 motorway to a point close to the Herefordshire town of Ross-on-Wye, where it joins the A40 road continuing westward into Wales. The motorway was fully opened in 1962.
The M73 is a motorway in Glasgow and North Lanarkshire, Scotland. It is 7 miles (11 km) long and connects the M74 motorway with the M80 motorway, providing an eastern bypass for Glasgow. The short stretch between Junctions 1 and 2 is part of unsigned international E-road network E05, where it continues along the M8 through Glasgow. To the south, the M74 motorway is also part of the E05.
Poyle is a largely industrial and agricultural area in the unitary authority of Slough, in the ceremonial county of Berkshire, England. It is located 18 miles (29 km) west of Charing Cross in London and immediately west of the M25 motorway, near Heathrow Airport; it also adjoins the Colne Valley regional park.
Iver railway station is situated in the village of Richings Park, near Iver, Buckinghamshire, England. It is the first station on the Great Western Main Line located outside Greater London, 14 miles 60 chains (23.7 km) down the line from London Paddington and situated between West Drayton to the east and Langley to the west.
The M63 motorway was a major road in the United Kingdom. It was completely renumbered as part of the M60 motorway in 1999 which orbits part of Greater Manchester.
The Glasgow Inner Ring Road was a proposed ring road encircling the city centre of Glasgow, Scotland. Construction of the roads began in 1965, and half of its circumference was completed by 1972, but no subsequent construction was made and the remaining plans were formally abandoned in 1980. After 30 years, the southern section of the proposals have become part of the new M74.
North Cross Route (NCR) was a planned motorway-standard road which would have formed the northern section of Ringway 1 and would have formed the innermost circuit of the London Ringways network. The six-lane dual carriageway with grade separated junctions to an extended M1 Motorway was planned during the late 1960s along with the rest of the Ringway scheme. It was never constructed due to large-scale opposition from many quarters.
The Johnsonville–Porirua Motorway is a motorway in Wellington, New Zealand. It forms part of State Highway 1, the main route of traffic in and out of the city. Completed in the 1950s, it was New Zealand's first motorway.
The Staines & West Drayton Railway (S&WDR) is a former railway on the western edge of London, England. It was about 5 1⁄2 miles (9 km) long and ran roughly north-south along the River Colne, parallel to the modern M25 motorway west of Heathrow Airport. It opened from West Drayton on the Great Western Main Line to Colnbrook in 1884 and reached Staines the next year.
The Colne Brook is a river in England that is a distributary of the River Colne which runs from Uxbridge Moor, there forming the western border of Greater London, to the River Thames just below Bell Weir Lock in Hythe End, Wraysbury, Berkshire.
The Thorpe Interchange is a large motorway free-flow intersection in Surrey, United Kingdom, connecting the M3 with the M25.