On the Brooklyn Extension the maximum grade is 3.1 per cent.
descending from the ends to the center of the East River tunnel. The
minimum radius of curve is 1,200 feet.

[Illustration: STANDARD STEEL CONSTRUCTION IN TUNNEL--THIRD RAIL
PROTECTION NOT SHOWN]

[Illustration: PLAN OF BROOKLYN BRIDGE STATION AND CITY HALL LOOP]

[Sidenote: _Track_]

The track is of the usual standard construction with broken stone
ballast, timber cross ties, and 100-pound rails of the American
Society of Civil Engineers' section. The cross ties are selected hard
pine. All ties are fitted with tie plates. All curves are supplied
with steel inside guard rails. The frogs and switches are of the best
design and quality to be had, and a special design has been used on
all curves. At the Battery loop, at Westchester Avenue, at 96th
Street, and at City Hall loop, where it has been necessary for the
regular passenger tracks to cross, grade crossings have been avoided;
one track or set of tracks passing under the other at the intersecting
points. (See plan on this page.)

The contract for the building of the road contains the following
somewhat unusual provision: "The railway and its equipment as
contemplated by the contract constitute a great public work. All parts
of the structure where exposed to public sight shall therefore be
designed, constructed, and maintained with a view to the beauty of
their appearance, as well as to their efficiency."