Only 11 Ottawa businesses have approached city officials to become partners in an underground shopping centre that's expected to be built once Ottawa's downtown tunnel is up and running.

Although few businesses have expressed interest, the man behind the downtown coalition of businesses says it's too early to write off the possibility of one day having an underground city.

"I think it's a little premature to expect a whole lot of concrete decisions at this stage. I mean, I think we have to define the project a little further," Hume Rogers told CTV Ottawa on Friday.

He said while some businesses are already in talks with the city's consultants and engineers, others are waiting until the project is further along.

Even once the tunnel is built, Hume predicts it will likely be years before Ottawa has a thriving underground city.

"It takes years to build that up - it did in Toronto, it did in Montreal; and it will in Ottawa."

City planners hope to begin construction on phase one of the project, which includes a downtown tunnel, by 2013.

City council will receive an estimate on the final cost of phase one of the transit plan next Friday.