at street, and the
material-disposal tracks and trestle. Fig. 3, Plate LII, shows the cuts
joined up and the excavation along the south side practically completed.

On the north side of the work, between Stations 182 + 90 and 183 + 65, the
rock was low, and provision had to be made for maintaining the yards to the
north of the site. Therefore a rubble-masonry retaining wall was built,
with the face about 2 ft. north of the face of the proposed concrete wall
which was to be put in later. On the same side of the work, between
Stations 188 + 24 and 188 + 46, the rock was exceedingly poor, and as a
small frame house on the adjoining lot was considered to be in an unsafe
condition, a rubble masonry retaining wall was built. As the building
adjoining the south side of the work at Tenth Avenue was on an earth
foundation, it was necessary to underpin it before the excavation could be
done. The building was supported on needles, and rubble masonry was put in
from the bottom of the old foundation to the rock. The foundation of 413
West 31st Street, immediately west of the Express Building site, was of
very poor masonry, and it was necessary to rebuild it prior to taking out
the adjoining excavation.

[Illustration: PLATE L, FIG. 1.--TW 23, P.N.Y. & L.I.R.R. Terminal Station
West. View looking Eastward from Tenth Ave., showing work between Ninth &
Tenth Avenues. Dec. 26, 06.]

[Illustration: PLATE L, FIG. 2.--TW 35, P.T. & T.R.R. Co. Terminal Station
West. View looking Northwest from Sta. 184, 120 feet South of center line.
Dec. 31, 07.]

[Illustration: PLATE L, FIG. 3.--TW 96, P.T. & T.R.R. Co. N.R. Div.
Terminal Station West. View looking West from Ninth Avenue Elevated
Railway, showing condition of work. May 26, 09.]

[Illustration: PLATE L, FIG. 4.--TW 104, P.N.Y. & L.I.R.R. Terminal Station
West. View from Tenth Avenue looking East, showing progress of concrete
walls. Aug. 7, 09.]

Along the north side, between Stations 186 + 50 and 187 + 50, the walls
supporting the adjoining back yards were of poor quality and had to be
renewed by the contractor before excavation could be done.

The excavated material was loaded by derricks on cars at the top of the
excavation, these cars being on tracks having a direct connection with the
disposal trestle, as shown by Fig. 1, Plate L. As soon as it could be done,
derricks were placed at the bottom of the excavation; tracks were then laid
out there, and the excavated material was loa