Niagara Tunnel

Ontario Power Generation | Canada | 2004–2013

2014 Award of Excellence
Canadian Consulting Engineering Awards

World's Largest
hard-rock-tunnel-boring machine was used in construction

More than 1.5 times
wider than the English Channel Tunnel


  • Niagara Falls is an awe-inspiring display of natural beauty, but it's also an important source of clean hydroelectric power.
  • Ontario Power Generation required an additional 500 m3/s (27%) of water-diversion capacity from the upper Niagara River to its Sir Adam Beck hydroelectric generating station.
  • The project called for the construction of a 10.4-km-long, 12.6-m-internal-diameter tunnel to provide an average annual energy increment of 14% (1.6-billion kWh), from a clean, environmentally friendly source.
  • Challenging ground conditions included rock with high in-situ stresses, prone to water-induced swelling.


  • As the owner's representative, we provided technical and management oversight.
  • Managed the preparation and negotiation of a three-part geotechnical baseline report.
  • Developed a two-pass lining system, consisting of initial rock support and a final liner made up of a double-layer, waterproofing membrane, cast-in-place concrete, and contact and pre-stress grouting.
  • Used steep grades at both ends of the tunnel to pass under an ancient buried gorge.


  • Completed ahead of schedule and under budget by $100 million.
  • Logged an exemplary safety record, twice the industry average.
  • Brought an additional $1 billion in economic benefit to the region.
  • Named the tunnel boring machine Big Becky in honor of Sir Adam Beck, the founder of the Hydro-Electric Power Commission of Ontario.
  • 2014 Award of Merit, Consulting Engineers of Ontario
  • 2013 Canadian Tunneling Project of the Year, Tunneling Association of Canada
  • 2013 Premier Project Award, Platts Global Energy Awards

“It was completed safely, with a safety record twice as good as the industry average. It will not operate for the next 10 years, or 25 years, or even 50 years, but for the next 100 years and more.”

Tom Mitchell | President, Ontario Power Generation

Project numbers

6.3 miles long
42 feet in diameter
500 m3 more water per second delivered to the generating station, enough to fill an Olympic-sized swimming pool in seconds.
C$1.6 billion cost of construction
Winner of 4 major awards

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