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Goin’ Underground Fig. 2: Two purpose-built, Canadian-made tunnel-boring machines, dubbed “Chip” and “Dale,” were launched to bore the seven interlocking “tunnel drifts,” forming the unique arched crown design of the main tunnel mixture to the project engineers for approval and This is not the first attempt at building a tunnel were soon given the authorization to proceed. to the Island Airport. In May 1935, Parliament Over 1200 tons (1010 tonnes) of King MS-D3 approved $1 million to build the tunnel, with Accelerated Macro-Synthetic Fiber Reinforced another $600,000 coming from the city of Shotcrete were applied throughout the 550 ft Toronto. On October 8, 1935, City Council voted (170 m) tunnel using an Aliva AL 252 dry-mix to approve the plan and work began in earnest shotcrete machine (Fig. 3). only days later. King provided a complete shotcrete solution, A long ditch was hollowed out along what is which included mixture design, equipment supply, now the Eireann Quay roadway, toward the material supply, and technical support. Represen- seawall of the Western Channel, while another tatives from King were on-site throughout the project ditch was burrowed on the island side leading to to assist with all aspects of the shotcrete operation, the north seawall. Steel sheet piles were ham- from equipment operation to product placement. mered into the ground to shore up the seawalls The next phases of the tunnel project will and enable excavation. include construction of the connecting terminal But work on the project ended as quickly as structures; installation of the moving walkways, it had started when, shortly after construction escalators, and elevators; landscaping; as well as began, the Federal Government issued an order electrical, mechanical, and final finishing work. to cease all work on the tunnel and fill in the When it opens, the pedestrian tunnel (Fig. 4) holes and ditches. will have four moving sidewalks traveling at 1.4 As for the steel sheeting, it had no effect on mph (2.3 kph). From a bank of six elevators on the topography or surrounding environment, and the mainland side, travelers will go 100 ft (30 m) was left in place. Fast-forward 77 years to the down to access the tunnel and travel along the construction of the new pedestrian tunnel at Billy passageway to the escalators, which will take Bishop Toronto City Airport. Geotechnical travelers to the airport’s check-in area. The com- plans and documents of public record indicated plete journey will take fewer than 6 minutes and that there were tunnel remnants underground, but will dramatically improve passenger flow. no one knew for sure what the pilings looked like. Shotcrete • Fall 2014 39


2014FallShotcreteEMag
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