It's expected up to six international firms will be among the bidders for Ottawa's $2.1-billion light rail project.

The City of Ottawa released a Request For Qualification Thursday to design, build, finance and maintain the light rail project.

The city's new light rail plan includes a downtown transit tunnel along a route that extends from Tunney's Pasture to Blair Road.

The RFQ document requires a submission that will build a light rail system "on budget and on schedule."

Firms will have until Sept. 13 to apply. A Request for Proposal will then follow. The final contract will be signed in Dec. 2012.

Construction on the project is expected take a period of five years.

The project was estimated to cost $2.1 billion in 2009. City Council will get an updated quote at a special meeting in July.