Vast curtain walls to the sky: Heathrow T5 takes shape, slated to open in 2008

Airline officials submitted the planning application for the $7.07 billion Heathrow T5 project in February 1993. After a detailed public inquiry, the government gave the go-ahead for the project in November 2001.

Now, with almost two-thirds of the work completed on time and within budget, T5,  the home of British Airways, exemplifies how future large-scale projects in the United Kingdom might be managed.

The concept
The design team from Richard Rogers Partnership of London worked closely with a multitude of end-users including HM Customs and Excise and retailers as well as BAA executives, each with different requirements, to integrate the project.

The single-span roof provides a vast and flexible interior space that can be adapted to the changing demands of the aviation industry. Travellers will experience simplified circulation and shorter walking distances.

After check-in, customs and security, departing passengers will descend from the departure lounge to the gates below. Through glazed façades, the passengers will enjoy views of the airfield.

Arriving passengers will make their ways into an open concourse with a view of the interchange plaza, a 30-meter-wide area running the length of the terminal. Glazed sky bridges span the interchange plaza and connect the terminal with bus, coach and taxi facilities integrated into forecourts of a multistory car park. Glazed express lifts at the northern end of the plaza connect rail services with the departures and arrivals concourses below.

Staggering statistics
The 16 projects and 147 sub-projects of the Heathrow expansion include: diversion of two rivers and the subsequent transfer of 40,000 fish; boring of 13.5-kilometer of tunnels; curtain walling of the vast 400-by-150-meter T5A building and its two large ancillary buildings; and the erection of an 87-meter traffic-control tower.

Reportedly the largest project currently under construction in Europe, the 260-hectare expansion covers an area roughly the size of London’s Hyde Park.

In its own right, the T5A building would be the fourth largest airport in Europe; more than 60,000 people are expected to work on the project throughout construction. While T5 will not add a runway, the extra space alone will boost capacity from 60 million to 90 million passengers per year.

Glazing solutions
Officials at Schmidlin Ltd. Façade Technology of Middlesex have worked with officials of BAA and HEK Manufacturing B.V. of the Netherlands to develop technical solutions and install the T5A curtain wall.

A test section of the cladding system was made and provided the team with a list of 140 possible improvements. Some of the framework from the prototype is  in the T5A structure.

Schmidlin officials have to design, manufacture, test and install 33,000 square meters of bespoke curtain walling, consisting of 5,565 individual elements. On the east and west elevations—spanning 400 meters and glazed from the exterior—the elements have a dimension of 3 meters by 2 meters. On the north and south side—spanning 150 meters and glazed from the interior—they measure 3 meters by 1.8 meters.

The glass units have laminated inner and outer panes with a high-performance coating on the second surface. The glass varies from 12.76-to-13.52-millimeter thick with a larger than usual integral air space to enhance acoustic performance. Parts of the western elevation opposite the car park were glazed with blast-enhanced units.

Dealing with structural movement
The main challenge lie in the amount of structural movement due to the huge façade spans. Schmidlin officials used an extruded movement gasket integrated into the design.
A further challenge was to find a solution for the external shading system. Even after coating the glass, solar-gain levels were too high.

A brise soleil, or a moveable wing-like sunscreen, was designed comprising 6-meter long blades and hung from the roof via 50-millimeter diameter solid stainless steel rods and cast stainless steel connectors.

Having to install two 400-meter-long façades with an outward inclination of 6.5 degrees, a roof soffit overhang of 8 meters and the limitation of not being allowed anchors or ties, called for special installation.

Together with T5 partner HEK Manufacturing, Schmidlin officials created a mast climbing work platform mounted on a bespoke rail track system that travels the length of the façade.

The platform incorporates sufficient load capacity for the glazing element manipulators and has enough storage area for a day’s supply of elements. Elements were installed at a rate of 10 per side per day on the east and west elevations, making a total of 20 elements installed per day.

Glass specifications
All elevations of the main terminal building are glazed with Super-Neutral 63 (SN63) of Guardian Industries Corp. of Auburn Hills, Mich. The north elevation uses Guardian’s Climaguard 1.1 Nuetralite Lowe.

Polypane Glasindustries NV of Belgium took delivery of the 40,000 square meters of glass required for the laminated outer pane, and the same quantity for the inner pane, which is clear float laminated.

For the roof, there are 8,000 square meters of toughened and heat-soak tested SN63 being installed by Hathaway Roofing of Bishop Auckland, United Kingdom. Polypane completed supplying Schmidlin with glass for installation in mid-August 2005.

Logistics
Having almost no site storage available, one of the first steps was to create a complete off-site logistics center. A logistics team is permanently based at the Heathrow warehouse complex to deal with deliveries from the Schmidlin manufacturing plant in Aesch, Switzerland, and transport to the site.

Approximately 10,000 square meters of storage space were required for the T5A façade materials. The pre-assembled glazing elements arrived from Switzerland in eight truckloads a week and the unitized construction needed a precise production sequence. Glass is loaded in the correct order to minimize handling.

Bringing vast quantities of other materials to the site by rail was instrumental in reducing construction traffic on local roads.

The T5 agreement
With lessons learned from the large projects undertaken in the past, airline officials wanted to avoid familiar pitfalls associated with large-scale construction projects by changing the way suppliers and partners work together. To this end, suppliers on the project worked under the terms of the T5 agreement, a legally binding contract between BAA and its key construction suppliers. Through the agreement, BAA accepts that it carries all of the risk for the construction project.

With the burden of accountability lifted, those working on T5 can innovate and work positively. While traditional arrangements often result in confrontation and high litigation costs if something goes wrong, under the T5 Agreement, a premium is placed on solutions and results.

Many T5 suppliers were brought in at the earliest stages of the planning process, working to identify problems and solutions.

BAA Project Director Andrew is precise about when the terminal will open: “At 4 a.m. on the March 30, 2008—and even the cappuccino will be the right temperature,” he said.

Key facts

• 16 major projects

• 68,000 square meters of roof

• 60 aircraft stands

• 30 million more passengers per year

Source:

www.baa.com/t5