Construction of the Eglinton Crosstown LRT line is now in full swing after a pair of tunnel-boring machines broke ground today in the city's west end near Black Creek Drive.

The two machines — named Dennis and Lea to represent the neighbourhoods of Mount Dennis and Leaside — will dig the underground portion of the line, heading east toward Yonge Street at a rate of approximately 10 to 15 metres a day.

Traffic on Eglinton Avenue near Keele Street was down to one lane in each direction by midday, according to CBC reporter Shannon Martin.

A second pair of tunnel-boring machines, named Don and Humber, will eventually begin digging westward from Leslie Street.

The province has billed the project as its largest public transit construction project in more than half a century, and says the line will help to ease congestion and create thousands of jobs.

"Our government is moving forward with the largest transit investment in a generation to get the region moving," Ontario's transportation minister Glen Murray said in a press release.

"The new Eglinton Crosstown LRT line will get commuters to work, school and play faster than ever before — up to 60 per cent faster than today."

Expected to be in service by 2020, the entire Crosstown LRT line will span 19 kilometres along Eglinton Avenue with a little more than 10 kilometres underground.

The line, which will include up to 25 stations, will link to 54 local bus routes, three TTC interchange subway stations and GO Transit.