TORONTO - The Toronto Transit Commission is building an extension to the subway system and is inviting the public to name the machines that'll dig the new tunnels.

Four large, powerful circular cutting machines will work in pairs below the ground on the Toronto-York Spadina Subway extension.

The 8.6-kilometre project will have two tunnels and the two pairs of machines will excavate and build almost in parallel.

It's a tradition to name the tunnel boring machines -- the machine boring a hydro tunnel in Niagara Falls, Ont., has been dubbed Big Becky.

Each entry for the Toronto contest must consist of two names and entries will be accepted online beginning Sept. 10 with the winner to be announced in November.

Contest winners will get to view the tunnel boring machine launch and the winning names will be printed on the four machines.