k signaling system as installed consists of automatic
overlapping system above described applied to the two express tracks
between City Hall and 96th Street, a distance of six and one-half
miles, or thirteen miles of track; and to the third track between 96th
and 145th Streets on the West Side branch, a distance of two and
one-half miles. This third track is placed between the two local
tracks, and will be used for express traffic in both directions,
trains moving toward the City Hall in the morning and in the opposite
direction at night; also the two tracks from 145th Street to Dyckman
Street, a distance of two and one-half miles, or five miles of track.
The total length of track protected by signals is twenty-four and
one-half miles.

The small amount of available space in the subway made it necessary to
design a special form of the signal itself. Clearances would not
permit of a "position" signal indication, and, further, a position
signal purely was not suitable for the lighting conditions of the
subway. A color signal was therefore adopted conforming to the adopted
rules of the American Railway Association. It consists of an iron case
fitted with two white lenses, the upper being the home signal and the
lower the distant. Suitable colored glasses are mounted in slides
which are operated by pneumatic cylinders placed in the base of the
case. Home and dwarf signals show a red light for the danger or "stop"
indication. Distant signals show a yellow light for the "caution"
indication. All signals show a green light for the "proceed" or clear
position. Signals in the subway are constantly lighted by two
electric lights placed back of each white lens, so that the lighting
will be at all times reliable.

On the elevated structure, semaphore signals of the usual type are
used. The signal lighting is supplied by a special alternating current
circuit independent of the power and general lighting circuits.

A train stop or automatic stop of the Kinsman system is used at all
block signals, and at many interlocking signals. This is a device for
automatically applying the air brakes to the train if it should pass a
signal in the stop position. This is an additional safeguard only to
be brought into action when the danger indication has for any reason
been disregarded, and insures the maintenance of the minimum distance
between trains as provided by the overlaps established.

Great care has been given to the design, construct