This is a railroad bridge that goes across the Cape Cod canal from the mainland onto the cape. Parking is at the end of Bell Rd. N 41° 44.450 W 070° 36.793.
More information on the bridge can be found
here.
Wikipedia: "The Cape Cod Canal Railroad Bridge (also known as the Buzzards Bay Railroad Bridge), a vertical lift bridge in Bourne, Massachusetts near Buzzards Bay, carries railroad traffic across the Cape Cod Canal, connecting Cape Cod with the mainland. While most lift bridges are kept down for land traffic to cross and lifted to allow boat traffic to pass under, the Cape Cod Canal Railroad Bridge is one of only a few lift bridges in the United States kept in an raised position and only lowered for the occasional land traffic."