Tunneling

Led by subsidiary McNally International out of Canada and McNally Tunneling Corporation in the United States, our tunneling expertise helps build the infrastructure that sustains healthy communities and supports growth and development.

Our deep tunneling work is executed throughout North America and supports the transportation of both fresh and waste water, as well as transit infrastructure like subways. We have a depth of experience building shafts and tunnels utilizing a broad range of methods, including Earth Pressure Balance (EPB), Mechanized Rock Tunneling, Drill and Blast Tunneling and Conventional Soft Ground Tunneling. We construct tunnels in a wide variety of sizes, with diameters ranging from one to 10 meters and lengths stretching up to 6,000 meters on a single heading. An internationally recognized leader, McNally has successfully completed over 800 kilometers of tunnels from coast to coast.

Types of Tunneling Expertise

Conventional Soft Ground Tunneling

This type of tunneling involves the use of traditional soft ground tunneling machines combined with temporary liners. In the right grounds this can still be one of the most economical methods of tunneling, especially for tunnels where a carrier pipe or secondary lining is required.

Earth Pressure Balance (EPB) Tunneling

McNally has been at the forefront of Earth Pressure Balanced (EPB) Tunneling since its introduction into North America. Combining the latest technologies with modern precast concrete liners, we have pushed the boundaries of this pioneering method, successfully completing projects in areas previously considered too difficult for tunneling.

Mechanized Rock Tunneling

McNally’s long history of using Mechanized Rock Tunneling dates back to the earliest days of hard rock tunneling in Canada. Our experience covers a wide spectrum of machines and techniques, from utilizing Main Beams to bore through unlined rock to employing Double Shields with secondary supports in fractured rock. We are also experts in modern rock tunnels, where rock machines are being utilized with precast concrete segmental liners.

Drill and Blast Tunneling

Drill and blast techniques, although less common since the introduction of modern machinery, are still utilized throughout North America. Our experience includes small adits to facilitate machine launches, shaft sinking through rock, and the construction of tunnels, often on multiple headings.

Cast-in-Place Linings

Many shafts and tunnels require a secondary lining. Paired with conventional tunneling techniques, liners can be a highly cost effective and timely method of tunnel construction for the right type of ground. Our experience covers all types of cast-in-place liners for shaft and tunnel, including installations for both jump-forming and slip-forming.

Tunnel Pipe Installation

Many tunnels serve the sole purpose of being a conduit for a pipe carrying effluent, water, oil, or gas. We have experience installing all types of pipes, both large and small. This includes concrete pressure pipes, HOBAS® pipes, T-Lock lined pipes, and High-Density Polyethylene (HDPE) pipes, along with steel pipes that meet oil and gas specifications. Each pipe installation within each tunnel can present unique challenges. Our in-house design team, combined with our deep experience makes us well equipped to rise to any challenge.