Road Tunnels

Broadway Underpass, Westlink, Belfast, Ireland

Design, under a DBFO contract, of a 500m long, 30m-span underpass, constructed using secant bored pile walls. The underpass, together with 3 major culverts, had to be built under existing city roads – design for appropriate methods of construction to deal with the ground level traffic, river diversions and very poor quality ground. The covered section of the underpass was designed to be built top-down to minimise the impact on the city centre site. 

Dublin Port Tunnel – Railway Crossing, Ireland

Independent design review of the temporary works for the construction of a dual carriageway beneath an existing railway embankment. Problems were experienced during the construction of this complex ‘pipe arch’ excavation under the live railway between Dublin and Belfast. The designer called Benaim in to do a detailed review of the design and construction and to solve the problems. 

Central Expressway, Singapore

Design for the contractor of 3.6km of cut-and-cover tunnels together with a five slip road underground interchange. The tunnels varied between dual 3-lane and dual 4-lane layouts, and had to cope with a variety of ground conditions and temporary works requirements. The tunnel crossed under the Singapore River and was constructed under the river in two halves (photo to the right).