Work has begun on the first phase of the $2.6bn project in Canada to extend the Yonge-University-Spadina subway line.
The phase involves a link from Wilson yard to the main route of the overall project, to extend the subway by 8.6km to link Vaughan's downtown core in the York region with Toronto's.
Work includes building six new transit stops from Downsview TTC station through to the Vaughan Metropolitan Centre.
The project is being funded by C$697m from the federal, C$870m from the provincial and C$526m from the city governments, and C$352m from the regional authorities.
The project is expected to be finished by 2015 and is expected to take nearly 30 million car trips off the roads from Toronto and the York region every year.