Screwed-up Riprap: Sizing Rock Linings to Resist Ship Propeller-jets

The only underwater international vehicular (automobile) tunnel in the world owes its existence to Fred W. Martin, a Windsor, Ontario Salvation Army Captain who said he was "inspired by God" to have the tunnel under the Detroit River built. It was not God, however, but the New York City engineering firm Parsons, Klapp, Brinckerhoff and Douglas (designers and builders of the Holland Tunnel in New York) who Martin visited one day in 1926 to see if such a tunnel could be built and operated profitably. Confident that the project was indeed feasible, and with urging from Martin who suggested that "it would probably be six dozen Sundays or more before the politicians would agree on anything, so how about taking a flyer on this as a private project?" the engineers not only agreed to design the tunnel but to guarantee its costs. The privately-financed, privately-built, and privately-operated 2.4 km (1.5 mi) tunnel connecting Detroit. Michigan and Windsor was completed in 1930 after 26 months of construction, and to this day is a major border crossing and a vital socio-economic link between the United States and Canada.