Cut & Cover

The Puerto Suello Tunnel is a 400 m long single-track rail tunnel in San Rafael, California and was constructed in 1879. The 4.9 m wide and 6.8 m high tunnel was partially destroyed by a fire in 1961, was rebuilt for freight service in 1967 and closed in the mid-1980s. The tunnel was acquired by SMART in 2003, who retrofitted and then reopened it for commuter rail service in 2017.

The ground overburden above the tunnel reaches a maximum of 45 m and the tunnel was constructed using cut-and-cover and mined construction methodologies.

Beacon Hill Station is part of the 22.5 km initial segment of Sound Transit's Central Link Light Rail. It is located 49 m below the ground surface in complex glacial soils with multiple groundwater horizons. The project comprises deep mined station tunnels and two 1.5 km long running tunnels excavated using a tunnel boring machine. The mined station was excavated through compressible glacial soils with multiple groundwater horizons using conventional mining techniques. The access shafts and station headhouses were constructed using slurry walls and cut-and-cover techniques.

Currently over 150,000 passengers use the station daily and with the completion of Crossrail in 2017, passenger numbers are expected to increase to over 200,000. The tunnels are of diameters between 4.0m and 11.0m and typically consist of a temporary sprayed concrete primary lining, a spray applied waterproofing membrane and a cast-in-place concrete secondary lining. Multiple transitions and interfaces to existing LU structures make for a challenging design and construction project under the busy streets of central London.

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.

The Beacon Hill Tunnels and Station are part of the 22.5km initial segment of the Sound Transit Central Link Light Rail Line that will establish a high capacity commuter connection from downtown Seattle to Tacoma. The 1300m running tunnel under Beacon Hill will be mined by Earth Pressure Balance Machine (EPB), while the deep mined Station will be constructed using slurry walls and the New Austrian Tunneling Method (NATM), referred to as Sequential Excavation Method (SEM) for this project.

The North Shore Connector Project consisted of three underground station structures and running tunnels, excavated with TBM and Cut-and-Cover tunneling methods. It also included a twin bore tunnel under the Allegheny River. Dr. Sauer and Partners provided design review and design support services. The development of the waterproofing system for underground structures including tying into an existing station using a flexible membrane system, combined with a sectioning system that allows for section grouting instead of the entire structure if a leak is detected was also provided.