Award

82 | FEBRUA RY 2015 Billy Bishop Toronto City Airport Pedestrian Tunnel Billy Bishop Toronto City Airport Pedestrian Tunnel by ROBIN BRUNET J on Hurt, principal for Arup, echoes the sentiments of many colleagues when he says of the soon-to-be-finished Billy Bishop Toronto City Airport Pedestrian Tunnel, "It's a fascinating project due to location and function, and unique in that it's fitted out to airport standards." The latter is understandable con- sidering the owner is the Toronto Port Authority (TPA) and the $82.5-mil- lion tunnel is intended to provide travellers with convenient, reliable and predictable access to Billy Bishop Airport, according to Ken Lundy, TPA director of Infrastructure, Planning and Environment. When complete, the tunnel will have four moving sidewalks travelling at 2.3 kilometres per hour. From a bank of six elevators on the mainland side, passen- gers will go 100-feet down to access the tunnel and travel 800-feet underneath Toronto's Harbour to escalators leading directly to the airport's check-in area. The complete journey will take less than six minutes and process 1,000 people hourly – a vast improvement over the ferry service that shuttled only 200 pas- sengers per sailing. The tunnel, which will be completed in early 2015, is being built through an innovative public private partner- ship agreement bet ween the TPA, Forum Infrastructure Partners and lead contractor PCL. A portion of the existing Airport Improvement Fee paid by departing passengers is also going towards the tunnel's construction. Forum Equity Partners, an eight-part consortium responsible for building, financing and operating the structure, "pulled together a team of participants including financiers," says Andrzej Gortat, principal at ZAS Architects + Interiors. "PCL Constructors was retained to handle the design build; they in turn hired Arup to be the prime con- sultant and tunnel designer, and Arup chose us to be the project's architect." The complex P3 arrangement was necessary to tackle a project that is, by nature, driven by engineering. "There were no preconceived design ideas other than TPA had certain specifications and wanted a tunnel to link the airport to the mainland near the downtown core," says Hurt. "An understanding of the ground conditions was the prime con- sideration, and this completely dictated the tunnel design." Fortunately, core sampling for a proposed bridge in the early 2000s that was ultimately aban- doned provided the tunnel partners with a strong understanding of the ter- rain under the Western Gap in Toronto's Harbour, between the Airport's main- land and island terminal buildings. Excavation of a 100-foot-deep main- land shaft located a mere 20 feet from the water's edge began in March of 2012 with a wall of interlocking con- crete cylinders constructed around the shaft to provide structural stability dur- ing the dig. "PCL managed to maintain the construction momentum despite very harsh winter conditions," notes Gortat. By December, the arrival of two Canadian-made boring machines her- alded the commencement of tunnelling. However, prior to the main tun- nel being excavated, seven 1.8-metre- diameter tunnels or "drifts" were bored, three of which were built to include new City of Toronto sanitary and water mains, helping to save Toronto taxpay- ers an estimated $10 million in dupli- cated construction efforts. "That was a major design innovation," says Hurt. "The smaller shafts allowed us to verify the integrity of the bedrock before the main tunnel was built. They formed an arch above where the main arched tunnel would be located, and once com- pleted they were in-filled with concrete for added strength." It's the first time in Canada that this pre-support technique was used. Technicore Underground Inc. began excavation of the main tunnel in June of 2013, and during the dig several spe- cial initiatives to compensate for site restraints were undertaken. One was a concrete batching assembly used to measure and mix ingredients to make concrete. This system minimized the number of trucks required to deliver concrete to the site; it also allowed trucks to deliver gravel and aggregate and leave the site loaded with excavated material – gantry cranes were used to raise and lower material into and out of the tunnel. In August of 2013, the core of the pedestrian tunnel was fully excavated, with tunnelling equipment breaking through to the island side. "Our in-house designed and built boring machines per- formed flawlessly," Technicore CEO Tony DeMillo told reporters. The next phase of the project – constructing the tunnel's skeleton – began immediately and was finished by December of that year. In addition to the tunnel, a new one- storey entry pavilion is being built at the foot of Eireann Quay. PCL completed pouring its concrete floor at grade in November 2014 with the erection of steel structure and glass walls quickly following. Similarly, a new glazed lobby with expansive views of downtown Toronto skyline was added to the exist- ing airport building at the Island side of the tunnel. "While the design principles were pre-determined by TPA, we suc- cessfully delivered on the Authority's vision for a timeless, sophisticated architectural expression seamlessly integrating the new tunnel termini with existing facilities on both the island and the mainland," says Gortat. Final stages of construction will include installation of the moving walkways, elevators and landscaping. Installation of large digital screens throughout the tunnel will provide pedestrians with f light and weather information as well as travel and res- taurant recommendations. In 2014, the Billy Bishop Toronto City Airport Pedestrian Tunnel proj- ect won the Tunnelling Association of Canada's Canadian Project of the Year award and the International Tunnelling and Underground Space Association's Specialist Tunnelling Project of the Year Award. "Right from the start, the Toronto Port Authority has worked to ensure that the tunnel was designed and constructed in a manner that puts the traveller experi- ence first," said Lundy. "Building a tun- nel of this scale and complexity while maintaining efficient operation of a busy airport is no easy feat, but we, along with our many partners, were up to the chal- lenge and are proud to have the project recognized by these two prestigious tun- nelling associations." A LOCATION 2 Eireann Quay, Toronto, Ontario OWNER/DEVELOPER Toronto Port Authority PROJECT MANAGER Forum Equity Partners LEAD DESIGNER Arup LEAD ARCHITECT ZAS Architects + Interiors GENERAL CONTRACTOR PCL Constructors Canada GEOTECHNICAL CONSULTANT exp Services Inc. TUNNELLING CONSULTANT Technicore Underground Inc. TOTAL LENGTH 800 feet TOTAL COST $82.5 million RENDERINGS COURTESY ZAS ARCHITECTS + INTERIORS PHOTOGRAPHY COURTESY TORONTO PORT AUTHORITY ARCHIVES, JAG GUNDU

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