On July 30, 2015 travelers catching a flight out of Billy Bishop Airport became the first passengers to descend below Lake Ontario to experience the engineering feat of one of the world’s first fully underwater tunnels from a mainland to an island airport, now open in downtown Toronto.
“PCL is proud to deliver this landmark project that fulfills PortsToronto’s vision of dramatically improving the passenger experience at Billy Bishop Airport,” said Bruce Sonnenberg, PCL Toronto district manager. “As travelers descend 100 feet below ground to travel a convenient six minutes through the passenger tunnel, they may not realize they are passing through an engineering marvel.”
The project, which broke ground in 2012, included excavation of vertical shafts on both the mainland and island sides. At 190m in length, and 6m high by 9m wide, the tunnel is one of the largest to be constructed within the Georgian Bay shale formation of the Greater Toronto Area.
In its role as design-builder, PCL delivered innovative solutions to combat construction challenges which included site and weather conditions, the logistics of building adjacent to an operational airport, excavating through shale, as well as the infinite water source present from Lake Ontario.
The team pioneered use of an innovative pre-support technique using seven interlocking horizontal bores, drilled by two tunnel boring machines and backfilled with fluid concrete. This permitted safe excavation of the main tunnel. Once the tunnel’s pre-support arch was in place, mass excavation began. To validate the tunnel’s structural design, the team utilized advanced computer and numerical analyses to simulate nonlinear, time and stress dependent swelling behavior of the shale rock, combined with a rigorous shaft and tunnel deformation monitoring program.
The project has been recognized with several prestigious awards, including the Specialist Tunnelling Project of the Year by the International Tunnelling and Underground Space Association, as well as the Canadian Project of the Year by the Tunnelling Association of Canada.
The Billy Bishop tunnel project adds to PCL’s portfolio of significant and technically challenging civil projects delivered throughout North America, including the Disraeli Bridges in Winnipeg, Manitoba; Glacier Skywalk in Jasper, Alberta; and Gilmerton Bascule Bridge Replacement in Chesapeake, Virginia. PCL’s civil construction operations are strategically located across North America to meet growing transportation needs.