Work begins on Britain’s longest railway viaduct

CONSTRUCTION of what will become the UK’s longest railway viaduct has commenced within earshot of the M25 near Denham, 18km north-west of Old Oak Common, writes Phil Marsh.

The 3.4km viaduct has a 120-year design life and is being formed from 1000 individual deck segments and 56 supporting piers made on site.

Every deck segment is unique because of the viaduct’s vertical and lateral alignment combined with a slight curvature. Rebar (steel) frames are constructed outside the factory using huge jigs, then moved inside the huge aircraft hangar type shed for concrete to be poured in giant moulds. Three segments can be made at a time, and up to 10 per week when the factory is fully up to speed.

The completed segments are moved into storage using a self-propelled platform on a rail mounted jig, awaiting their turn to be installed. Production commenced in mid-February and installation will commence by the end of April.

PHIL MARSH The Colne Valley Viaduct factory and some of the supporting piers it has already made, as pictured on March 16.