Manchester united.

A new footbridge in an anodyne area of central Manchester forms a landmark as well as an urban link.

Facing each other across a Manchester street are two of the flagships of the booming British retail economy: Marks & Spencer, the great clothes and food emporium, and the Arndale Centre (a sort of shopping mall, modelled on the American type, but not as flash). Instead of firing broadsides at each other across the street (which was devastated by an IRA bomb in 1996), the two have decided to link with a sort of gang plank so that shoppers can pass seamlessly from one to the other without having to dodge traffic or face the weather.

The two new buildings are not particularly noteworthy, but the bridge in its tube is a remarkable structure, and a memorable landmark in the city. Designed by Hodder Associates with Ove Arup & Partners, a tube slopes slightly downwards from Arndale to M&S. Tapering towards the middle of the span, the structure is an elegant triangulated steel basket, formed in hyperbolic paraboloid geometry out of 110 mm tubes welded together and linked in lattice by tie rods and four circular structural hoops.

The twisted geometry stiffens the tube and allows individual members of the curved structure to be straight, just as the triangular glass panes suspended within the basket are plane, and so easily joined with flexible silicone pointing. The ends of the structure are contained within compression rings.

A timber deck is supported on I beams which transfer its loads to the hoops. Its gentle ramps are relieved by two horizontal landings. Glass balustrades support stainless steel handrails and slatted panels extend into the gap between deck and cladding. (It remains to be seen how this detail will stand up to the tender mercies of the British public, notoriously the filthiest and most litter-prone in Europe, but the extended deck will at least allow the inside of the glass to be cleaned easily.) The bridge is ventilated naturally, and lighting and heating is carried under the deck.