The North Clark Street Bridge was the last of the swing bridges that were replaced in downtown across the Chicago River (by a pony truss bridge in 1929) . It has a clear span of 215 ft, a width of 72 ft, and each leaf weighs 2800 kips.
Today, these bridges are only opened about 40 times a year. Note how the trusses becomes deeper at their ends to support the counterweights as they rotate into the pits behind each tender house. The North Clark Street Bridge was rebuilt many times, with the last rehabilitation in 1985.
Movable Bridges - North Clark Street Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.