Fisher Street, Crossrail C300/410

Construction of concrete tunnel lining of crossover structure linking the eastbound and westbound main train tunnels.

Tunnel to be formed in 10 pours, formwork to be easily moved and adjusted to each new pour location. Tunnel width varies to suit headwalls at location of tunnel mergers. Access required through formwork support for operatives and small plant. Pour lengths vary to suit head walls at tunnel mergers. Longitudinal inclination of tunnel, curvature of tunnel. Concrete to be placed by pump in confined working spaces. Lateral loads on support system due to cross passages, etc.
SL1 H.D. Support system with Top50 Formwork. Travelling formwork moved between pours via flanged wheels on rails with the aid of tirfors/plant. System lowered with lowering wedges and levelled for next pouring cycle using hydraulic hand pumps. Support frame provides good access by using knee braces to create central opening. Working platforms provide access for operatives to adjust the formwork with spindles and for placing and vibrating concrete with use of SCC pumping ports and external vibrators attached to the Top50 formwork.