TYNESIDE REPORT 8. PART 2: CONSTRUCTION

This article describes the constructional features of the new sections of the Tyne and Wear Metro. The largest is the 2.1 km long tunnel from Jesmond, under central Newcastle, to Forth Banks. Tunnel diameters are 4.75 M compared with London's 3.85 M. Tunnelling operations were complicated by the need to underpin the foundations of Newcastle Central Station and the need for compressed air in pockets of water-bearing sand. Twin 800 M long bored tunnels beneath Gateshead are flanked by cut-and-cover sections at each end. Two new bridges have been built. The through-train bridge over the River Tyne was chosen because it was strong, economical and of compatible appearance with the four existing bridges. The 815 M long Byker viaduct spanning a difficult side over a steep sided valley, was the first to use glued segment concrete cantilever construction in the UK. The viaduct has 18 spans and 253 precast deck segments. The Monument station, at the centre of the Metro, has been built in stages and roofed over to keep at least half the street open for buses and pedestrians. For abstracts of parts 1 and 3 of this article see IRRD nos 248772 and 248774.