The Toronto Port Authority says it will be building a $45-million pedestrian tunnel to the Billy Bishop Toronto City Centre Airport.

"We're going to build a tunnel that's esthetically beautiful," Geoffrey Wilson, the federal agency's president and CEO, said Monday.

"It's going to be very functional, very easy to use, very pleasing to use for those who haven't previously experienced using a tunnel to access an airport. I think it will anchor the airport and allow us to manage continued growth of passenger volumes."

The tunnel will be paid for through a public-private partnership and by applying an airport improvement fee, he said.

The current airport improvement fee is $15. That is expected to rise to $20, compared to $25 at Pearson International Airport.

The 123-metre-long tunnel will be built 30 metres below the surface of Lake Ontario. Crews will start work on the island side and build towards the mainland.

An environmental assessment is underway, with the design phase being the next step.

If all goes according to plan, construction will begin in the spring of 2011 and take at least two years to complete.

Passengers currently use a ferry to access the airport. The ride takes about 90 seconds. The ferries will still carry passengers after the tunnel is built and will also be used to move vehicles and supplies to and from the island.

About 1.3 million passengers are expected to use the airport this year. The authority has argued that rising passenger volumes are one reason why the airport requires more than one point of entry.

Porter Airlines is the main carrier, but Wilson said two new carriers will start offering flights in December.

Because the project doesn't involve building on or over city land, it doesn't need any approvals from the city of Toronto, he said.

With a report from CTV Toronto's Alicia Markson