The Straits of Mackinac Shipwreck Preserve are divided in two by a bridge spanning how long?
Straits of Mackinac Shipwreck Preserve The Straits of Mackinac Shipwreck Preserve is a 148 sqmi state preserve in and around the Straits of Mackinac. The preserve is divided in two by the Mackinac Bridge. The waters of the preserve include the waters offshore from Mackinaw City and St. Ignace, as well as all or part of the shorelines of Bois Blanc Island, Mackinac Island, Round Island, and St. Helena Island.
Monocacy River bridge and viaduct The Monocacy river bridge and viaduct is a 326 ft open deck steel girder bridge with two main spans crossing the river and 2 viaduct sections crossing the floodplain, south of Walkersville, Maryland. Originally constructed by the Frederick and Pennsylvania Line Railroad Company (F&PL). Construction began in late 1871, and continued until July 1872 when the railroad opened that year. It was rebuilt by the Pennsylvania railroad prior first in 1900-1905 as an open deck riveted iron plate under girder bridge. In 1915, the bridge was surveyed as part of the Interstate Commerce Commission's ("ICC") effort to establish freight rates for the Parent railroad. In 1927, the Pennsylvania railroad rebuilt the bridge again using deeper and thicker steel girders, but leaving the masonry piers intact. In 1972, the two 85 foot river spans were washed out by Hurricane Agnes. In 1982, the State of Maryland purchased the bridge as part of the railroad line. In 1995, the State rebuilt the river spans and Pier 3 which is located in the middle of the river crossing was completely reconstructed using concrete to replace the original masonry foundations. In 2015, the State performed minor maintenance on the structure and painted some spans. 