Transactions of the American Society of Civil Engineers, vol. LXVIII, Sept. 1910

he structures, and these were carried on posts; they were changed alternately until the excavation had been taken out to a depth of about 16 ft. below the surface. In placing these I-beams, heavier blocking was used in the center of the span than at the ends where the bents would come, to prevent the subsidence of the track owing to the sag in the I-beams. As much excavation, to a depth of about 20 ft., was taken out adjoining the elevated railway foundations as could be done with safety. Fig. 2, Plate XLVII, shows this condition of the work. The 48-in. brick sewer was broken, and the sewage was pumped across the excavation.

The overhead girders "B" were then put in place, and two of the girders "C" were used as temporary shoring girders at each column. These, as shown by Fig. 3, Plate XLVII, were placed parallel to the elevated railway, with blocking between them and the girders "B." Double bents, independent of each other, were placed under the ends of these temporary shoring girders, and these were brac