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Transactions of the American Society of Civil Engineers, 1986, Volume 151
Transactions of the American Society of Civil Engineers 1986 Volume 151 Author:American Society of Civil Engineers Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: free of the columns ; and, since the attachments are purposely made weak, the result of a vessel's striking the bridge with its hull will be to tear them away an... more »d swing the span to one side. Should the rigging of the vessel, however, strike the span, the effect will be simply to break off the masts without injury to the bridge. This latter accident has happened once already, the result being exactly what the writer had predicted. There is a special apparatus, consisting of a heavy square timber set on edge, trimmed on the rear to fit into a steel channel which rivets to the cantilever brackets of the sidewalk, and faced with a 6 x 6-in. heavy angle iron, to act as a cutting edge. This detail, which is a very effective one for destroying the masts and rigging of colliding vessels, is shown in the photograph of the structure reproduced on Plate II. The adoption of a wooden handrail on the span, while a steel one is used on the rest of the bridge, is a wise precaution against expense caused by collisions. The wooden rail is easily replaced by any carpenter, and is quite cheap; while the steel rail, if broken or bent, as it is liable to be, would be not only costly, but also difficult to match in replacing, and comparatively expensive to repair. Of course, the wooden rail is not quite so sightly as the metal one. The writer had contemplated using the latter over the entire structure, and conceded the change to a wooden rail with some reluctance, but is now convinced that it is the proper thing for the place. This wooden rail and the exterior guard are standard devices of the City Engineer's office of Chicago. The bridge is designed to carry a double-track street railway, vehicles and foot passengers, as can be seen by the photographic view shown on Plate II. It has a clear roadway ...« less