Amid news that Porter Airlines has placed an order for 12 jet airplanes and options on 18 more, a lesser known project is well underway at Billy Bishop Toronto City Airport, and it set to change how Toronto's other growing airport currently operates.

The 'Island' airport has become an important hub for business commuters and regional leisure travellers. With Porter Airlines facilitating much of this growth, the little air transport hub that could has become a major player in the regional travel market, owing its success to its proximity to Toronto's core and the ease of use commensurate with its smaller size.

Owned and operated by the Toronto Port Authority (TPA), the airport constitutes the western quarter of the Toronto Islands. Passengers currently access the airport via a TPA ferry, a short journey across the channel. After years of contemplation around how to 'bridge' the island airport, the TPA is now over a year into construction of its underground pedestrian tunnel under the Western Gap of the Toronto Harbour.

Cross section of the pedestrian tunnel, image courtesy of TPA and Zas Architects

An obviously complicated engineering task, builder PCL is busy everyday mining, pouring, and welding for an estimated completion in Spring-Summer 2014. Nearly 40 metres deep below the lake surface, the tunnel will span 240 metres under the channel, providing passengers with easier access to the airport via a moving walkway. The $82.5 million tunnel is being financed through a public-private partnership, ultimately paid for by an Airport Improvement Fee of $20 per departing passenger. 

Chip (TBM) being lowered into mainland trench, image courtesy of Toronto Port Authority

Chip (TBM) breaking through island side trench earlier this year, image courtesy of Toronto Port Authority

Island side of tunnel excavation, image courtesy of Anthony Galloro

The project is a collaborative effort; ZAS is the architectural team, with Arup on the engineering design. Technicore, the tunnel contractor, has sourced two Canadian-made Tunnel Boring Machines (TBM) to create an arch of 7 mini tunnels that will serve as the canopy for the main tunnel (see below). Chip and Dale, the TBMs, drill through more than 12 metres of rock every day, and have already broken through on the opposing island side.  

Diagram of tunnel sequence, image courtesy of TPA

New island link terminal looking south, image courtesy of TPA and ZAS Architects

Pedestrian tunnel looking south, image courtesy of TPA and ZAS Architects

Airport terminal pavilion, image courtesy of TPA and ZAS Architects

Airport terminal pavilion, image courtesy of TPA and ZAS Architects

With expected completion about a year from now, there are high expectations for the quality of service the tunnel will introduce for users of the island airport. Though the ferry will still operate, passengers will have an added option for accessing the island, one that is sure to spark fascination in some as they walk beneath one of the Great Lakes.

Island Airport construction overlooking downtown Toronto, image courtesy of Anthony Galloro

Want to know more about the project? Click on the UrbanToronto dataBase entry linked below. To join in on the conversation, choose the linked Projects and Construction Forum thread, or leave your comments here.