It extends eastward from the station under 32d and 33d Streets through
tunnels partly three-track and partly so-called twin tunnels to Second
Avenue; thence the line curves to the left under private property to
permanent shafts a few feet east of First Avenue. Four single-track,
cast-iron, concrete-lined tunnels, with outside diameters of 23 ft.,
pass under the East River, and, after passing through permanent shafts
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.