Eads Bridge

The superstructure consisted mainly of 3 steel arches, the largest that had ever been constructed. It was also the first to be built of spanded bracing, and the first to be built of cast steel. The Encyclopedia Brittannica called them "the finest example of a metal arch yet erected." They were built out from the piers from both ends to meet in the middle and were put into place without staging from below, this also was the first instance of such work. All the working platforms and machinery were suspended from temporary towers built on the piers, so that while the arches were being put up navigation below was not interfered with. This accomplishment along with the sinking of the piers presented some of the most difficult problems ever attempted by an engineer. One problem caused by the fault of the contractors presented itself when they came to insert the central tubes to close the arches. The tubes were found to be two and a half inches too long to go in, although they would only be the required length after they were in.
Eads solved this problem by cutting the tubes in half, joining them by a plug with a right and left screw. Then he cut off their ends, for the plug would make them any required length by inserting or with drawing the screws a little. It would have been much cheaper not to use this device, his assistants tried for hours to shrink the tubing by ice applications to get the arches closed. There is a popular tradition that they succeeded, but the weather was so hot they did not. Any part of this steel work can safely be removed and replaced. This was another structural feature original in this bridge. Mr. Eads took care to patent all these special innovations.
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