DETAILS OF DESIGN FOR VIADUCTS.

The specifications for the "Details of Design for Trestles and Elevated Railroads" are in general to be followed as far as they will apply in the designing of highway viaducts, the principal variation being that, for cheap structures, adjustable rods with clevises may be substituted for the stiff diagonals in the four faces of the braced towers, by adding, of course, horizontal struts at the panel points of the transverse and longitudinal bracing. These struts must be riveted to the columns by means of wide plates to which the clevises attach, and must never be pin-connected. Corner horizontal plates are to be employed for attaching the horizontal adjustable rods by means of clevises, each of said plates being riveted to both a transverse and a longitudinal bracing strut.

The detailing for the longitudinal girders of viaducts and the bracing between same shall comply with the specifications for detailing highway plate or open-webbed, riveted girder spans; and the specifications for wooden floor system, paving, hand-rails, etc., shall be the same for highway viaducts as for highway bridges.