Mott MacDonald has been the lead designer for all of Terminal 5’s substructures. Even though the visible parts of T5 are huge, like an iceberg they are dwarfed by its unseen underground structures – the basements, foundations and tunnels.

These huge unseen subterranean basements house baggage handling and storage halls, underground railway stations and five tunnels which are 14km in total length. We also designed five aircraft taxiway bridges,
provided project and programme management, and certified the
new rail tunnels for use.

Heathrow Terminal 5 is one of the most acclaimed construction projects of recent years. Costing £4.3 billion, T5 is the largest single building project in Europe by value, and its physical scale and scope are similarly enormous. T5 consists of three buildings whose square footage adds up to more than all of Heathrow’s existing terminal buildings put together.

T5A and T5B are already built; T5C substructure is in place and the superstructure will be erected and ready for use by 2010. In addition, there are 60 aircraft stands, a new air traffic control tower and over 13km of bored tunnel.

All construction has been carried out around, and without disrupting, BAA’s operation of Heathrow Terminals 1, 2, 3 and 4. It will open to operations on 27 March 2008 on time and under budget.

Even though the visible parts of T5 are huge, like an iceberg they are dwarfed by its unseen underground structures – the basements, foundations and tunnels, all designed by Mott MacDonald. These huge unseen subterranean basements house baggage handling and storage halls, underground railway stations and five tunnels which are 14km in total length. We also designed five aircraft taxiway bridges, provided project and programme management, and certified the new rail tunnels for use.

More than meets the eye

The main T5 basement is believed to have been the largest ever excavated in the UK. Foundations for T5B and C are smaller, but were vast undertakings in their own right. Road, rail, baggage, passenger transit and drainage tunnels have had to be constructed adjacent to and underneath the new terminal buildings, and beneath the airport’s taxiways and aprons. Individually, each tunnel was a significant project.

They include extensions to the Heathrow Express and London Underground Piccadilly Line rail tunnels, the Airside Road Tunnel, Stormwater Outfall Tunnel and a light rail passenger transit tunnel connecting the three terminal buildings.

Delivering these subterranean works involved delicacy and precision. Innovative design and construction were informed by findings of original research, significantly reducing costs and time against schedule, and improving safety. Tunnelling and foundations innovations played an important part in meeting BAA’s objectives of realising exceptional value, preventing cost escalation, and of reducing health and safety risks.

All aspects of geotechnical design were carried out by Mott MacDonald with input from civil engineering main contractor Laing O’Rourke, piling subcontractors Bachy Soletanche and Expanded Piling, and tunnelling contractor Morgan Est. We supervised construction. Mott MacDonald also designed rail systems for the new Heathrow Express and Piccadilly Line extensions and, separately, approved those systems for use.

A collaborative approach

Terminal 5 is one of Europe’s largest and most complex construction projects. With 16 major projects and over 147 sub-projects, it has encompassed a vast and hugely complex programme of works. Lauded by many as a template for major construction projects of the future, Terminal 5’s unique framework contract pushed the boundaries of traditional construction by encouraging collaborative working, promoting design innovation and harnessing best practice from other industries and translating it into mainstream construction management.

Client: BAA
Architect: Richard Rogers and Pascal & Watson
Designer (below ground): Mott MacDonald
Designer (above ground): Ove Arup
Constructor (substructures): Laing O’ Rourke
Contractor (tunnelling): Morgan Vinci JV

Start/finish dates: September 2002 – March 2008