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 braced securely to prevent possible dislodgment
during the removal of the rock. The weight of the structure was then taken
by jacking up the girders near the bents until the column was lifted off
the old foundation; blocking was put in between the girders and the bents
during the jacking, so that when the jacks were released the base of the
column was still clear of the old foundation. One 80-ton jack was used for
this purpose, and the general method is shown by Fig. 1, Plate LII.

[Illustration: FIG. 4. (Full page image)

METHOD OF EXCAVATING NINTH AVENUE PLAN AND ELEVATION SHOWING VARIOUS STAGES
OF THE WORK]

[Illustration: FIG. 5. (Full page image)

METHOD OF EXCAVATING NINTH AVENUE SECTIONS SHOWING VARIOUS STAGES OF WORK

No. 1

Condition Prior to Commencement of Work