The Manhattan bridge

The Manhattan Bridge was completed at the beginning of the 20^th century. It is very pleasing in the design. Especially noteworthy is the improvement in the appearance of the towers. The flexible design of the towers permits them to bend to and fro with the variations in length and the sag of the cables, and makes possible a design of slender proportions. The Manhattan Bridge was the work of the engineers of the Department of Bridges of the City of New York. The Manhattan Bridge also represents an improvement in the technique of suspension bridgebuilding. For example, a new method for erecting the towers was devised. Each tower of this bridge consists of four steel columns, which are supported on a cast steel pedestal that rests, in turn, on a masonry pier. The tower columns were erected by the use of ingenious derrick platform (one for each pair of columns). Each platform projected out from the face of the tower and was supported by two bracket struts below. Then a derrick was mounted on the platform and the sections of the tower (weighing up to 62 tons) were lifted from the top of the pier and set in place. When a full section had been added to the tower, the derrick platform lifted itself to the next level with the aid of block and falls.

With the towers completed, the next step was the construction of a temporary footbridge, which would connect the two shores.

The Manhattan Bridge was thus the first suspension Bridge to amplify modern suspension bridge construction technique. It stands, carrying the increased loads of present-day traffic without a tremor. Architecturally and structurally, it deserves to be included among the great engineering works of the twentieth century.

Дата добавления: 2015-08-27