The Blue Water Bridge is a twin-span bridge that spans the St. Clair River between Port Huron, Michigan and Point Edward, Ontario (near Sarnia, Ontario). The Blue Water Bridge connects with Highway 402 in Ontario and with both Interstate 69 and Interstate 94 in Michigan. The original span is a cantilever truss bridge and the second span is a continuous tied arch bridge.
The first bridge is a cantilever truss with a total length of 6,178 feet (1,883 m). The main span is 871 feet (265 m). The second bridge is a continuous tied arch with a total length of 6,109 feet (1,862 m). The main span is 922 feet (281 m). The twinning project was a combined effort between Modjeski & Masters - U.S Engineers and Buckland & Taylor Ltd. - Canadian Engineers. During the construction, two temporary masts were erected to assist in the construction of the tied arch, the towers were painted red and lighted, enabling them to be seen from afar.
Together, the two bridges are one of the busiest transportation arteries between the United States and Canada. They also provide one of the four shortest routes of land travel between the eastern seaboard of the United States, and the central United States. The Blue Water Bridges are jointly owned and maintained by Canada and the United States. The Blue Water Bridge Authority is in charge of the Canadian side, and the Michigan Department of Transportation (MDOT) is in charge of the U.S. side. The bridges charge a toll, which is used to pay for bridge maintenance and operations.
A second three-lane bridge, just south of the first bridge, opened on July 22, 1997. As a precursor to this project, the customs and toll collection booths on both sides were extensively reconfigured (in Canada, the original booths in use since 1938 were demolished). The first bridge was immediately closed afterwards for renovation and reopened in 1999; the newer bridge used a similar 3-lane configuration for a couple years. A flyover ramp on the US side temporarily diverted westbound traffic from the new bridge to the toll plaza, which was blocked off after the original bridge was rehabilitated.
During the debate over five possible designs 1994-95, over half of public opinion had mostly favored a duplicate of the first bridge, while the cable-stayed bridge came in second with around 21%. The Blue Water Bridge Authority had rejected both designs, due to the duplicate creating a false sense of history, while the cable-stayed option was feared to overshadow the existing bridge. The continuous-tied arch design, which was a distant third place in polls, was chosen for two reasons. One was that it blends in with the original span yet stands out on its own, and the other is lower maintenance costs because fewer spans are involved.