Heathrow Cargo Tunnel
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The Heathrow Cargo Tunnel is a road tunnel in the London Borough of Hillingdon, London, UK.
The tunnel was built in the late 1960s to connect Terminals 1, 2 and 3 to the (then new) cargo terminal at Heathrow. The tunnel is not open to the public: it is used only by vehicles with security clearance to drive airside. It is now used for cargo movements and transfer of passengers to and from Terminal 4 (Terminal 4 was built next to the cargo terminal in 1986). From 1972 a public bus service (route 82) operated through the tunnel. With the opening of Terminal 4 in 1986 a number of other bus routes also passed through the tunnel. This was an odd situation as anyone could board the bus, and travel "Airside" without going through any form of security checks. In the interests of security all public bus services where withdrawn from the tunnel in 1989. All buses now enter the central area through the main tunnel.
The cargo tunnel is bi-directional (it has one bore, carrying one lane in each direction). Each lane has width 3.66 m with clear height 5.03 m. The tunnel consists of approximately 625 m of circular bored tunnel with 130 m of rectangular cut and cover tunnel at each end. Its total length is 885 m.
The bored tunnel segments are precast concrete, 33'9" (10.29 m) internal diameter, 12" (0.3 m) thick and are expanded directly against the ground (which is London clay). The bored section of the cargo tunnel is notable among tunneling engineers, for having been constructed with a remarkably thin cover of solid clay above it (minimum cover 1.2 m clay beneath the Terrace gravels).
There is one sump in the tunnel, at a low point about 300 m north of the south portal.
The tunnel is one of the few in the United Kingdom that is ventilated by a fully-transverse system (it has an air supply duct in the invert of the tunnel, and an air extract duct in the crown of the tunnel). Extract and supply fans are sited in underground chambers at the north end and south end of the tunnel, at the TBM launch and TBM retrieval chambers.
Consulting Engineer for the works was Sir William Halcrow and Partners, with Hoare Lea & Partners advising on electrical and mechanical services. The tunnel was built by Taylor Woodrow Construction, with E&M fitout by Halliday Hall and Aerex.
The cargo tunnel was the only privately-operated road tunnel in the United Kingdom until March 2005, when the Heathrow Airside Road Tunnel was opened to airside traffic just next door to it.
[edit] References
- Muir Wood, A. M. & Gibb, F. R., Design and Construction of the cargo tunnel at Heathrow Airport, London, Paper 7357, Proc. Instn. Civ. Engnrs., Vol 48, 1971
- Discussion of paper 7357, Proc. Instn. Civ. Engnrs., Vol 48, 1971
- Map showing Heathrow Cargo Tunnel.
