s
near the bulkhead line, reach the surface in Long Island City from 3,000
to 4,200 ft. east of the East River. The tunnel portals are in
Sunnyside Yard, which extends to Woodside, the easterly end of the
Division, and the Yard grading with its buildings and a number of City
viaducts crossing it were executed under this Division. The total length
of the Division is 4.48 miles.

The total length of the entire line is 13.66 miles. There are 6.78 miles
of single-track tube tunnels, and the average length of the tunnels
between portals is 5.56 miles.

[Illustration: PLATE II.--Pennsylvania Tunnel and Terminal Railroad. Map
and Profile. Harrison Yard to Bergen Hill Tunnel. Meadow Division July
30 1909]

GENERAL CONSIDERATIONS.

Details have been omitted from the foregoing description, as they can be
treated better and more fully by the constructing engineers in
succeeding papers. There are, however, some general considerations
involved in the designing of the work, which may, perhaps, be referred
to more conveniently in this introductory paper, and these will now
receive attention.

In all parts of the work problems were encountered requiring for their
solution large expenditures and much engineering skill; but many of
these difficulties had been frequently met in previous engineering
experience, and the methods of overcoming them were well understood.
Thus, in the Meadows Division, a long and heavy embankment, part of
which was on submerged meadow land, and many bridge foundations had to
be constructed; in the Bergen Hill tunnels, very tough trap rock was
encountered; in the tunnels under the city, the work was much
complicated and its cost increased greatly by the necessity of caring
for sewers, water and gas pipes, and the foundations of adjacent
buildings; and many troublesome problems were met in the construction of
the tunnels connecting the East River tunnels with the Sunnyside Yard.

The novel features of the project, however, were the great tunnels
extending the line under the North and East Rivers. Tunnels of the kind
contemplated, to be used for heavy and rapid railroad traffic, had never
been constructed through materials similar to those forming the beds of
the North and East Rivers. Questions arising in connection with the
design and method of construction of the tunnels will be considered
later. Here they are referred to only in their relation to the location
and grades of the line, in which connecti