The TTC has filed a $10-million breach-of-contract lawsuit against the engineering firm contracted to oversee construction of the new Vaughan Metropolitan Centre subway station.

The lawsuit against Arup Canada alleges the company failed to meet the terms of its contract in a number of ways. The allegations have not been proven in court.

The TTC alleges the contractor failed to meet building and electrical codes on the site and did not use skilled, competent staff. It also says Arup failed to meet the contract's schedule.

The station, located near Highway 7 west of Jane Street, is the final stop on the Toronto-York Spadina subway extension. A statement on the TTC's website says the $2.6-billion extension is slated to open in the fall of 2016.

TTC president Andy Byford would not comment on the lawsuit. But he did say opening the line on time would be a challenge.

"We've identified ways that the contractors need to accelerate their program, they are struggling to get additional resources to apply to those stations," he said. "But I won't know for certain until my engineers have had time to review the program as to exactly what that means in terms of duration and cost.

"Our plans to open the line remain scheduled for late fall 2016 but we do know that is going to be a challenge at a number of the sites. My project team is working with the contractors to see what's possible."

In a written statement, Andrew McAlpine of Arup Canada said they are proud of their contribution to the project and are confident they can reach an amicable resolution to the lawsuit.