The Beck tunnel boring machine (alternately Big Becky) was the largest tunnel boring machine in the world, when it was operated by Ontario Power Generation, from 2006 to 2011.
[1] Hydro used it to bore a deep replacement tunnel to supply water from the upper Niagara River 10.2 kilometres (6.3 mi) to the Sir Adam Beck Hydroelectric Plant.
The tunnel was delayed when Beck encountered a bed of loose material, unsuitable for boring, that required a detour.
[2] According to Ontario Power Generation the TBM itself weighed 2000 tons.
[3] However, when its task was complete, Western Mechanical, the firm that removed Beck, described it weighing 7000 tons.