DETAILS OF STEEL GIRDERS, ETC. SUPPORTING NINTH AVENUE STRUCTURES]

_Supports for Surface Railway Structure._--A uniform load of 3,000 lb. per
lin. ft. of single track, with the weight of a car at 39,000 lb., was
assumed. Several feet of earth, between the structure and the rock, were
mined out, and the structure was supported on I-beams and posts, and
ultimately on the transverse girders by using timber bents under the
I-beams, as shown on Fig. 3.

_Water Mains and Sewer._--Cradles were designed for the support of the
48-in. and 24-in. water mains, resting on the transverse girders, and the
48-in. cast-iron sewer on the east side of the avenue was carried on
I-beams bracketed to the ends of the transverse girders, as shown on Figs.
1 and 2.

[Illustration: FIG. 2. (Full page image)

METHOD OF SUPPORTING ELEVATED RAILWAY STRUCTURE]

[Illustration: FIG. 3. (Full page image)

METHOD OF SUPPORTING TRACKS OF NEW YORK CITY RAILWAY CO.]

_Girders "C."_--The transverse girders below the street surface, referred
to above, were known as girders "C," and they were put in place at first
resting on concrete piers on the central core; the weight of all structures
was placed on them while the sides of the avenue were being excavated, and
the sides of the viaduct were being built. The ends of these girders were
then picked up on the sides of the viaduct, and, spanning the central rock
core, carried all structures while the core was being excavated and the