Tunnel Design & Specialities

The Dr. G. Sauer Corporation was responsible for the NATM design of the lower escalator, station tunnels, cross adits and emergency access shafts at City Place Station, the only underground station in the Dallas' Light Rail System. Excavation of the station chambers took place 85 ft (26 m) below the road deck of the new North Central Expressway cutting and within 115 ft (35 m) of the adjacent foundations of the multistory City Place tower block. The large 59 ft x 59 ft x 23 ft (18 m x 18 m x 7 m) domed mezzanine level chamber is one of the largest free span caverns constructed in medium soft rock in the US to date. The two station platform tunnels are 79 ft (24 m) apart (centerline to centerline) and involve several cross adits of various sizes with relatively narrow pillars of chalk between. Through a series of comprehensive calculations, the size of openings, excavation sequences, size and advance of headings, the shotcrete and cast-in-place concrete lining requirements were specified.

The Dublin Port Tunnel is an approximately 3.5 mile long twin, two-lane tunnel which connects the M50 motorway and Dublin Airport with Dublin Harbour. The underground connection will help to manage the rising traffic demands and will carry up to 20,000 vehicles per day upon opening. The overall scheme consists of 2.8 miles of tunnels, where 1.3 miles are Cut-and-Cover and the remaining 1.5 miles are TBM bored 35ft.

London Underground Limited have extended the Jubilee line from Green Park to Stratford in East London. The Jubilee line Extension is 15.4km long and located predominately underground with several new stations along its route. London Bridge Station (Contract 104) is one of the major stations and includes comnnections to, and an up-grade of the existing Northern line Platforms. The main contractor, a Costain-Taylor Woodrow Joint Venture, commissioned Dr. Sauer & Partners to design the NATM works which comprised running tunnels, station tunnels, ventilation tunnels, and concourse tunnels as well as temporary access headings with internal spans of between 4.8m and 11.3m. The tunnels were excvavated predominately in London Clay with NATM works starting in the spring of 1994 and being completed in 1996.