Execution

Ottawa's Confederation Line runs from Tunney's Pasture station in the west to Blair station in the east, is 12.5 km long and includes 15 stations. The central piece is a 2.5 km long tunnel, running under the central business district of the city and including three underground stations. The twin track running tunnel and the three underground stations were constructed using the mined construction method in order to minimise surface disruption. The underground stations are located directly adjacent to existing, sensitive and historic buildings and required strict adherence to design and risk mitigation processing during construction. The Dr. G. Sauer & Partners on site team supported the contractor to meet these requirements.

Luck Stone Corporation (LSC) is the nation's largest family owned and operated producer of crushed stone, sand and gravel. At their plant in Leesburg, Virginia, Luck Stone Corporation acquired a new quarry, which is located to the West of Goose Creek river. An inter-quarry tunnel was constructed to link the existing South-Eastern pit with the new West pit. The tunnel's cross section is approximately 45 feet in diameter, and the tunnel's length is approximately 1275 feet. The tunnel crosses the Goose Creek river approximately 50 feet beneath. The excavation method was drill and blast in hard rock (diabase).

Bank Station is a London Underground station located in the City of London financial district. It is a key interchange served by five existing lines. The Bank Station Capacity Upgrade (BSCU) aims to relieve heavy passenger congestion during peak hours for boarding, alighting and interchange. The capacity upgrade comprises the construction of a new southbound platform tunnel and associated length of running tunnel for the Northern line, connecting passageways to the existing station tunnels, and the provision of step-free access from King William Street. The total length of tunnels is 1,300m with tunnel cross sections that range from 10m2 up to 90m2.

The constructed tunnel is part of the City Trunk Line project in L.A. (replacement of an existing water trunk line). The tunnel is located at the junction of Riverside Drive and Whitsett Avenue. It is between eight and ten feet in diameter and has a total length of 252 feet. To fit between the existing structures in the ground (foundation piles of a bridge), the tunnel follows an S-shape and is divided into sections with different geometries. The tunnel was built using NATM/SEM construction methods. The primary support measures included fibre reinforced shotcrete, lattice girders and spiles (rebar spiles and grouted pipe spiles).

University Link is a 5km light rail extension that runs in twin-bored tunnels from Downtown Seattle north to the University of Washington, with stations at Capitol Hill and on the University of Washington campus. The project further includes 20 cross passages located in soft ground and a maximum design water head of 60m. To deal with the prevailing geological conditions, specific ground support categories were developed. Steel fibre reinforced initial lining, sheet membrane waterproofing and CIP final lining were utilised.

A major collapse during construction of the Thierre Tunnel in 2009 led government officials to call on NATM experts to come up with an innovative fix for the 5.6km, two-lane twin tunnel, which is part of the new Reshen Kalimash Motorway. Recommended stabilisation measures by the Dr. Sauer/iC JV such as backfilling, ribs and fibre shotcrete were implemented and halted creep movements. An alternative design was developed and replaced the original horseshoe profile by an ovoid shape. Pre-treatment, excavation works and support installation were accompanied by extensive monitoring.

The City of Edmonton built a 3.3km Light Rail Train extension from Churchill Station to the Northern Alberta Institute of Technology. Approximately 670m of the extension are underground consisting of ca. 430m of twin tunnels of 6m nominal diameter. NATM/SEM tunneling was applied. The software 2DOC, which was at that point used in North America for the first time, allowed real-time tracking of all geotechnical instruments on the project, as well as the recording of the actual geotechnical conditions and the grout support elements installed.