Three years after Crosslinx celebrated the removal of the two tunnel boring machines (TBMs) at Yonge nicknamed Don and Humber for Toronto's coming Crosstown LRT, the remaining two TBMs—nicknamed Dennis and Lea—have been now extracted too. Don and Humber dug westwards under Eglinton Avenue from just west of Leslie Street, and Dennis and Lea dug eastwards from just east of Black Creek Drive. All four finished up at Yonge Street where an interchange station with the Yonge line is being built through the cut-and-cover method. 

This latest milestone occurred last month, before social distancing measures and work site limitations were introduced. Tunnelling on the Metrolinx-led project was launched in 2012 and completed in 2016 by all four TBMs. Once all TBMs had excavated their combined roughly 10-kilometre paths from launch shafts at Keelesdale Park in the west and Brentcliffe Road in the east, they terminated at points east and west of Yonge Street. The east TBMs were extracted in March, 2017, while the west TBMs sat idle for about four years prior to their removal last month. This was necessary in order for excavation to be completed at Eglinton Station, down to the LRT's tunnel depth of 20 metres.

In early March, the first sections of TBMs were removed, including the 10-metre diameter steel-toothed cutting heads that carved the path for the new transit line.

Cutter head removal in early March, image via blog.metrolinx.com

A time-lapse video highlights the removal process of the main TBM bodies, requiring a massive mobile hydraulic crawler crane parked in the middle of Eglinton Avenue between Duplex Avenue and Yonge Street. Even with the large crane, the TBMs had to be disassembled into smaller sections to allow for their removal from the extraction shaft.

After boring through just shy of seven kilometres of twin tunnels for the line's western leg, the TBMs—each measuring 6.5 metres in diameter, 10 metres in length, and weighing a whopping 400 metric tonnes—have taken on significant wear. The removal of cutting heads is offering a rare view inside one of these TBMs, shared by Metrolinx, where the complex inner workings of the machine can be seen looking well-used. Due to the extensive length bored by the TBMs, they have been deemed beyond their lifespan and will not be re-used.

View inside one of the west TBMs from late March, image via blog.metrolinx.com

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ED NOTE: An early version of this story had the names of the TBMs reversed.