TUNNEL – TAKE TWO
Tunnel 80 Years in the Making Makes its Debut
It’s not really surprising that when governments change, so do civic priorities. New leaders come in and the commitments and goals of the prior regime are often quickly discarded as a new vision for the future takes shape. Such was the case in 1935, when a change in government led to the filling in of a tunnel on which construction had begun in an effort to connect Toronto’s mainland to the island 400 feet to its south.
It all began in the 1930s, when the Toronto Harbour Commissioners, precursor to what is today known as Ports Toronto, began considering plans to build an airport on the Western Sandbar (now the northwestern part of Toronto Island). The Great Depression had slowed planning and development in the city, and there were concerns that Toronto would fall behind in the growing commercial aviation industry if investment weren’t made in this area. As both a means of getting people back to work and a show of confidence in the future of transportation in Toronto and the surrounding area, Conservative Prime Minister R.B. Bennett announced that an island airport would be constructed. But a tunnel would need to be built first so people could get to it.
In May 1935, Parliament approved $1 million to build the tunnel, with another $600,000 coming from the City of Toronto. On October 8, 1935, city council voted to approve the plan and work began in earnest only days later on a tunnel to the island. Alderman Sam McBride did not approve and did his best to stop construction.
Despite his isolated opposition, a long ditch was hollowed out along what is now the roadway known as Eireann Quay toward the seawall of the Western Channel, while another ditch was burrowed on the island side leading to the north seawall. Steel sheet piles were hammered into the ground to shore up the seawalls and enable excavation.
However, work on the project ended as quickly as it had begun. In late October 1935, a federal election was held and Bennett was defeated by William Lyon Mackenzie King’s Liberals. King, a close ally of McBride, issued the order to cease all work on the tunnel, and to fill in the holes and ditches. As for the steel sheeting, it had no effect on the topography or surrounding environment and so was left in place. In 1939 an airport was built despite the access challenges flagged by Bennett.
Fast forward 74 years to 2009 as the airport becomes a thriving transportation gateway. An airport was built, despite the access challenges flagged by Bennett, and became a thriving transportation gateway welcoming millions of travellers each year. It was this success that re-ignited discussion regarding the need for fast, reliable and predictable access to the airport.
As such, Ports Toronto began discussions to construct a tunnel to the airport. During these discussions, the organization learned of a City of Toronto plan for a major infrastructure project under the Western Channel that would connect much-needed water and sewer mains to the island – a plan that would parallel the proposed pedestrian tunnel.
“We identified the opportunity early on to complete the projects in tandem,” said Ken Lundy, Vice President of Infrastructure, Planning and Environment, Ports Toronto. “By incorporating the city’s water and sewer mains into the tunnel construction, we could save taxpayers approximately $10 million and also eliminate the need for additional, redundant construction and the associated disruption to the neighbourhood.”
Arup, Ports Toronto’s tunnel consultant engineers, came up with an innovative design to drill seven, six-foot-high interlocking “drifts” across the top of the tunnel, forming an structural arch that would permit excavation to continue under the tunnel’s crown, while allowing the tunnel to hold its shape.
“Not only was this the first time in Canada such a pre-support technique would be used, it would also allow the city’s planned water and sewer mains to be incorporated directly into three of the tunnel’s drifts, effectively combining both major projects into one,” continued Lundy.
Excavation of the 100-foot-deep mainland and island shafts of the tunnel began in early 2012. Once digging on the two shafts was complete, two purpose-built, 36-foot-long, Canadian-made tunnel boring machines dubbed “Chip” and “Dale” were engaged to bore the seven interlocking “tunnel drifts,” forming the unique arched crown design of the main tunnel. The first tunnel drifts broke through to the island side in January 2013, marking a significant milestone in the tunnel’s construction. By August of that year, the approximately 853-foot tunnel had been fully excavated, establishing the first land link between mainland Toronto and the island.
Today, the tunnel has come full circle and been transformed from dirt, shale and rock under the Western Gap into an innovative passageway through which travellers can get to and from the airport in less than six minutes. The tunnel’s unique design and construction won the International Tunneling &
Underground Space Association’s 2014 Specialist Tunneling Project of the Year Award and the Tunneling Association of Canada’s 2014 Canadian Project of the Year Award.
As for the steel sheeting left over from 1935, these remnants of the past were rediscovered during the current excavation, serving as a reminder of the colourful history of today’s pedestrian tunnel to Billy Bishop Airport.