Main Street Tunnel Main Street Tunnel The Main Street Tunnel, located in Welland, Ontario, Canada, is an underwater tunnel, carrying Niagara Road 27 and the unsigned designation of Highway 7146 under the Welland Canal. It is named as a part of East Main Street. The structure was built as a part of the Welland By-Pass project. Its construction was relatively easy since, like the Townline Tunnel, it was constructed at the same time as the channel above it and a simple cut and cover. The tunnel was officially opened on May 20, 1972. The tunnel links Highway 406 on the west side of
Channel Tunnel at the English portal, caused concerns. Identified by the 1964–65 geophysical survey, the Fosse Dangaered is an infilled valley system extending below the seabed, south of the tunnel route in mid-channel. A 1986 survey showed that a tributary crossed the path of the tunnel, and so the tunnel route was made as far north and deep as possible. The English terminal had to be located in the Castle Hill landslip, which consists of displaced and tipping blocks of lower chalk, glauconitic marl and gault debris. Thus the area was stabilised by buttressing and inserting drainage adits. The service tunnel acted