Bridges presentation
The Saint Charles Airline
Railway Bridge (1919) spanning 16th Street in Chicago was at 260ft (79m) the longest single-leaf
bascule when it was completed. In 1927, the Atchison, Topeka & Santa Fe Railroad built the world's
longest single-span swing bridge, 525ft (160m), over the Mississippi at Fort Madison, Iowa. One of
the most interesting and unusual moveable bridges is the Lacey V Murrow Bridge (1940), whose
design reached back to the pontoons built by Roman legions. The depth and breadth of the lake
precluded the construction of conventional piers on pilings, cantilever, or suspension spans, and so
Washington State bridge engineers designed a floating bridge supported by hollow concrete
pontoons to connect Seattle and Mercer Island. Equally unique was the retractable floating draw
span for ocean-going ships in the lake. Three other bridges of this type were completed over the
Hood Canal (1961) and at Evergreen Point (1963)
annaabi.ee 
