to the forward panel point will be ignored; or, in other words, the uniform load will be treated as if concentrated at the various panel points.

In deck-spans on sharp curves, after the centre curve for each rail and the centre lines of the longitudinal girders are laid out, the approximate extra live load on the outer girder due to the projection of the curve of the rail beyond its centre line near mid-span is to be computed and added to the regular live load; but the corresponding excess of dead load from the flooring, being small, is to be ignored. As the superelevation provides for an equal distribution of the live load on the rails for the assumed medium velocity of trains, there will be an excess of live load on the outer girder due to the velocity being sometimes greater than this; but the said excess is so small that it is to be ignored.

The excess of live load on the inner girder, due to the velocity of train being sometimes less than that assumed for determining the superelevation, is offset by the reduced load due to the projection of the centre line of the rail near midspan beyond the centre line of the girder; so it also is to be ignored.

LIVE LOADS.

The live load to be used in designing any railroad structure shall be taken from the "Compromise Standard System of Live Loads for Railway Bridges and the Equivalents for Same," which is given in Chapter XIX and in Plates I, II, III, and IV.

In single-track bridges but one of the seven classes of loading given can be used for any span; but in bridges having more than one track two or even three classes of loading can be used in the same span, if so desired by the Engineer: for instance, Class W could be adopted for stringers, Class X for cross-girders, and Class Y for trusses, thus utilizing the theory of probabilities.

The equivalent live loads given on the diagrams are to be used instead of the actual wheel concentrations.

For elevated railroads the live loads are generally to be very