A new transit line under Eglinton Avenue is finally being dug, nearly two decades after a previous attempt was killed.

The first of two east-bound tunnelling boring machines began turning Wednesday morning and will inch its way about five kilometres through the glacial till.

The machine is dubbed Dennis. Its mate, named Lea, will start a parallel tunnel later in the summer. They will run 20 hours a day, deep underground, sending truckloads of spoils back to the launch shaft near Eglinton and Black Creek.

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Two more TBMs – Don and Humber – will start in the east end of the city head toward the core, where they will meet Dennis and Lea.

The Eglinton Crosstown is a light-rail transit route that will run underground for about 11 kilometres across the core of the city and on the road at its western and eastern ends. It will have a dedicated right of way when on the road, meeting the definition of higher-order transit.

According to the regional transit agency Metrolinx, it will cut travel time dramatically across the corridor.

"We are not going to be second-class citizens in the world anymore when it comes to transit," Transportation Minister Glen Murray said at the launch Wednesday.

The minister, who threw the red Hollywood-style lever to start the machine turning, said the $4.9-billion project will benefit even those who don't use transit.

"These are going to take a lot of cars off the highway," he told assembled reporters and construction workers.

Developers have already reacted to the coming transit line with a boom on Eglinton. And Toronto Chief Planner Jennifer Keesmaat has spoken about the city's centre of gravity shifting north.

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The western section of Eglinton, beyond the Allen expressway, was to get higher-order transit under a 1980s plan called Network 2011. Governments changed and the plan went through several iterations before the Progressive Conservative administration of premier Mike Harris killed the Eglinton subway in the mid 1990s.

The preliminary excavation was filled in and will play no part in the upcoming dig.