'Chip', one of the two tunnel boring machines being used to construct the pedestrian walkway to Billy Bishop Toronto City Airport, has completed one of the drift tunnels and broken through the tunnel's shaft wall on Toronto Island.
The Canadian-made tunnel boring machine was lowered into the tunnel shaft at the foot of Eireann Quay on January 10 and began drilling on January 12. Its twin, 'Dale', is currently beneath the Western Gap creating one of seven drift tunnels that will form the walkway's crown. 'Chip' will be returned to the mainland to begin work on the next drift tunnel.
The walkway crown will be arched and comprise seven smaller, interlocking tunnels (six feet/1.8 metres) designed to reduce the potential for water ingress during construction. These tunnels will be constructed to form an arched roof for the walkway. Three of the drift tunnels will carry city mains to the Toronto Islands.
The Toronto Port Authority is building a pedestrian walkway across the Western Gap to Billy Bishop Toronto City Airport. The 800-foot walkway will be completed in Spring 2014 and will be the only known pedestrian tunnel in the world that connects to an airport and sits beneath a body of water.