Timber bents were erected on girders "C" to carry the I-beams under the
surface railway structure, as shown on Fig. 3, and all temporary posts
under these I-beams were removed. The bents were framed with a jack, as
tightly as possible, and very little settlement of the track occurred.

A cradle was then built under the 24-in. water main and placed on girders
"C," and, as a temporary footwalk had been constructed on the west side of
the avenue, it will be seen that all structures were thus carried on
girders "C."

All structures were put on the girders "C" before continuing the excavation
on the sides of the avenue because, in case of a slide of rock, there would
be less danger than to individual structures. The outside piers, on
which the girders "C" rested, might even be lost, without affecting the
stability of the structure, and posting could readily be done beneath these
girders in case of necessity.

A very careful record of levels, taken on the elevated railway columns, was
kept, observations being made during each jacking up and at least twice a
week during the progress of the work. The columns were usually kept about
1/2 in. high so as to allow for compression in the timber bents.

As a rule, no jacking of the elevated railway structure was done while
trains were passing over, and trains were flagged during the operation.
There was generally very little delay, as all jacking was done between
10.30 A.M. and 2.30 P.M., when the traffic was lightest, and frequently the
jacking was done between trains, causing no delay whatever. Steel clamps
were placed, three on the top and three on the bottom of each set of the
girders "C," to bind them together and cause them to act as a unit.