Lastly, some bridges are composed of cantilevers and suspended girders.
The cantilevers are fixed to the shore side of the towers.
In length and attached to the cantilevers by links.
The cantilevers can stiffened suspension bridge, but atter the fall of the Tay bridge in 1879 this was abandoned.
The length of the cantilever bridge is 5330 ft., made up thus: central tower on Inchgarvie 260 ft.; Fife and Queensferry piers each 145 ft.; two central girders between cantilevers each 350 ft.; and six cantilevers each 680 ft.
The outer ends of the shore cantilevers are loaded to balance half the weight of the central girder, the rolling load, and 200 tons in addition.
The centre girder may be built on the cantilevers and rolled into place or lifted from the water-level.
In this case the shore ends of the cantilevers are anchored to the abutments.
Waddell has shown that, in some cases, it is convenient to erect simple independent spans, by building them out as cantilevers and converting them into independent - (5) The Poughkeepsie bridge over the Hudson, built 1886-1887.
The girders over the second and fourth spans are extended as cantilevers over the adjoining spans.
The shore piers carry cantilevers projecting one way over the river openings and the other way over a shore span where it is secured to an anchorage.
The side girders rest on the cantilevers on 15-in.
The girders weighing 2000 tons carry a double track for trains between the girders and on each side on cantilevers a trolley track, roadway and footway.
The arms are elliptical in cross-section, diminishing from the nave to the rim, and are usually designed as equally loaded cantilevers, fixed at the nave and free at the rim.