This is what the mouth of the tunnel looked like before the hammering started. If you look closely at the archway over the top of the central shaft, you'll notice it's made up of seven circular tubes of concrete. Those tubes extend all the way to the mainland. They're basically tiny tunnels, each one made with a boring machine and then filled in. Their main purpose is to prevent the tunnel from caving in.
The Toronto Port Authority’s 800-foot-long pedestrian tunnel to Billy Bishop Airport celebrated a major milestone today when a giant, truck-mounted jackhammer smashed through a wall of shale located about 100 feet below street level.
The break-through marked the end of excavation on the tunnel, which has been under construction since March 2012.
While the underground walkway will be sure to displease anyone who opposes the growth of Billy Bishop Airport for whatever reason, it will have its advantages. When it opens—which it’s expected to do in summer 2014—anyone who needs to get from the mainland to the airport will be able to catch an elevator down to the tunnel. Moving sidewalks will carry passengers underneath Lake Ontario to a bank of escalators, which will lead directly into the airport’s check-in area.
At the moment, this entire journey is done on the surface, by ferry. The distance is only around 600 feet, but waiting times can draw the trip out to 20 minutes or more. It’s estimated that walking the tunnel will only take six minutes.
The scene outside the tunnel. Photo by Tony Makepeace/Torontoist.
Today’s break-through, attended by throngs of media and officials, happened slowly, over the course of about an hour. A huge pneumatic hammer, mounted on a heavy construction vehicle, pounded away at a slab of shale at the lowest point of a deep pit about the size and shape of a ten-storey building. Thick plumes of dust wafted through the air as bits of stone tumbled to the ground. Eventually, large shelves of shale began falling away in heaps. When the tunnel opening had been excavated all the way up to its concrete ceiling, a bunch of dusty construction workers in orange safety vests clambered out of the hole and into the sunlight like rescued miners. They let up a cheer.
The job has been a complex one. In a sense, the tunnel had been completed many times over before today. Boring machines were used to dig nine small, concrete-filled shafts to be used as guides and supports for the central walkway. The walkway was then excavated with the giant vehicle-mounted hammer.
The tunnel’s estimated $82.5 million cost is, according to the Toronto Port Authority, being financed entirely by a private consortium and paid for with airport user fees.
Though the excavation, by contractor Technicore Underground, is now more or less complete, the tunnel will still need a substantial amount of interior finishing before it’s ready for use.
Click through the image gallery for a closer look at all the smash-and-crash action.