STEELWORK group Severfield-Rowen is undertaking a £2.4m trial run in preparation for building the roof of Terminal Five, at Heathrow Airport, near London.

The trial is taking place at its headquarters at Dalton Airfield Industrial Estate, near Thirsk, North Yorkshire.

The 35-metre-high framework - which can be seen from the A1 - has been built to simulate the work that will take place at Heathrow.

"It may look like something from a sci-fi film set, but it is a vital test run for building the stunning roof which will span Terminal Five at Heathrow when it opens in 2008," said Mark Cowieson, project leader for the British Airport Authority.

The trial is being undertaken to prove and streamline the roof assembly method before construction begins at the end of the year.

As far as possible, the conditions the project team will face during construction have been recreated at Dalton.

"The constraints at the terminal site itself, just yards from one of the world's busiest airfields and situated between the two runways, mean when we start assembly for real in November, we have to get it absolutely right," said Mr Cowieson.

"The principal objective was to practice constructing one of the most difficult sections of the roof and support structure before repeating the process at Heathrow."