The Crosstown light rail transit line got a lot less boring today. Metrolinx and its contractors celebrated the end of tunnel-boring for the project as they lifted the cutting head of one of two tunnel boring machines from a shaft on Eglinton Avenue East at Holly Street, just east of Yonge Street.
It took a couple hours of standing in the frigid cold March air before we glimpsed sight of tunnel-boring machine, "Don," appearing above ground for the first time in more than a year. Signal persons stopped all traffic on Eglinton between Holly and Dunfield Avenue to allow a crane to safely operate above the street.
The crane lifted the 100-tonne 'business end' of the machine from the pit, swung it over Eglinton and then laid it onto the ground about 20 metres east of the original site. Later tonight, the crane will lift the part onto a truck and remove it from the site.
The contractors completed the entire 'cutting-edge' operation in just ten minutes. "We're excited because this is a major milestone for the project," explained John Brown, the chief engineer for the east tunnel portion of the future transit line. Brown said that digging in an urbanized environment had its challenges, but he was proud that his team had managed to complete the task ahead of schedule.
Metrolinx plans to remove the rest of Don from the site in pieces over the next several days. Wednesday, March 15, they intend to uproot the forward shell from the shaft. This Friday, March 17, it's the turn of the trailing shield. Finally, crews will lift the last piece, the stationary shield, from the hole, Thursday, March 23.
Once the team has totally cleared Don from the site, they'll start moving its twin, "Humber." It currently lies under the south side of Eglinton, where traffic is now flowing. The crews must move that machine to the north side of the street—to the extraction shaft—before they can start removing it, again bit by bit.
While this is a milestone for the project, the consortium building the line still has lots of work to do. Contractors will continue to work on building the stations, laying track, installing power, signals and other systems for the underground portion of the line. They'll also start working on the street-level tracks and stations east of Brentcliffe Road (between Laird Drive and Leslie Street.)
In September, 2015, Ontario Minister of Transportation Steven Del Duca joined Metrolinx chief executive officer Bruce McCuaig and members of the Crosstown team to launch of the two east tunnel-boring machines from a shaft on Eglinton East near Brentcliffe. Don, the machine digging the north tunnel, began its 10-kilometre journey to Holly Street September 29. Humber starting its trip to build the south tunnel October 29.
The two machines altogether each weighed 400 tonnes, standing ten metres high and six metres across. Six-person crews operated the machines 24 hours a day about 20 metres underground. Each machine created tunnels 5.7 metres in diameter and moved westward about 10 metres a day. They installed 26,178 precast tunnel liners to form 2,182 rings as they excavated. Each ring consists of six concrete segments make up one ring. Each cycle to build a ring requires about an hour for the machines to complete.
The borers propelled themselves forward by pushing against each newly installed ring of liners. A conveyor removed the muck that the machines dug out. According to Metrolinx, the volume of material that the tunnel borers extracted could fill the ACC to the height of the CN Tower. Don and Humber arrived at the Holly Street site last August.
Metrolinx used two other boring machines, "Dennis" and "Lea" to build the west tunnels between Black Creek Drive and Yonge Street, with digging for these tunnels beginning in September 2013. Dennis and Lea were then dragged over the TTC's Line 1 subway tunnel at Eglinton West Station during an April 2015 community event. The machines arrived at their final destination on Eglinton at Duplex Avenue—just west of Yonge—in May 2016. Metrolinx and its contractors will extract these two machines at a later date before station construction begins at the site. Metrolinx expects to open the line to passengers in 2021.
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