FECATC.TXT
The ATC is effective between Sunbeam and North Miami, or, in other words, between
the yard limits at Jax and Hialeah.

The ATC uses this hardware: there are three displays in the cab. The cab
signal display is mounted on the divider between the middle front
windshields, and consists of LEDs arranged in two sets of three like a
set of signals, and a alertor beeper. The engineer's panel is on top of
the control stand, and has LED indicators for speed, time-to-penalty,
decelleration rate, and system status. There are pushbuttons for light
intensity, and circuit test, and another alertor beeper of a different
tone. The conductor's panel is mounted in the front cab wall behind the
left numberboard. It has a speedometer, and system status indicators.
There is an axle generator on the #1 axle for speed sensing, in addition
to the usual generator on the #2 axle, which is for the speed recorder.
(The two signals must compare within 6 mph or a penalty application is
made.) There is a solenoid valve in the penalty brake pipe, and a
pressure sensor in the train brake pipe. Underneath the pilot at both
ends of the locomotive are two coils above and inside the rails. The
reverser handle selects which set of coils is being read. There is an
acknowledgement pedal on the floor at the engineer's feet. The
electronics are housed under the cab floor in a box about the size of
the proverbial breadbox.

The wayside system (that is, the electronics connected to the signals
beside the track) feeds a coded signal to the rails in addition to the
signal that detects the presence and movement of the trains. The signal
is sent from the DISTANT signal. In other words, as you pass a signal
that is say, clear, the cab signal is being sent from the next signal
down the road. This signal is decoded by the onboard equipment to
indicate what signal to display. Any interruption of the signal is taken
as a restricting signal. When the signal changes to a more restrictive
signal than the one currently displayed, the new signal is displayed and
the alertor goes off, which must be acknowledged within 8 seconds, or a
penalty brake application is made. (A penalty application is one that
cannot be recovered from before it has completed it's cycle. The train
brakes are applied at a controlled rate, and the PC switch is opened,
removing power from the locomotive.) <Watch out for that slack!>

Now that the engineer has acknowledged the signal, the system calculates
the time-to penalty. This is based on what it would take to stop a 100
car train of 100 ton hoppers with 6,000 hp. The ttp is displayed for the
engineer, and a LED graph shows whether the rate of decelleration is
adequate to meet the ttp, and the engineer's alertor warns of impending
penalty. When the specified speed is reached, the system returns to it's
normal state, displaying only the signal and speed. 

The speed authorized for the various signals are: Clear, 65 mph.
Approach-intermediate, 15. Approach-home, 12. Restricting, 15, after
falling below 3. Approach diverging, 40. Advance approach, 40. Diverging
route clear, 40. Diverging route approach, 12. Advance approach is
displayed 14,000 feet before the approach signal. 2,000 feet before
reaching a positive stop at a home signal, the cab signal will go to
single red restricting. The speed must then be reduced to 3 mph or less,
but then can be increased to 15 if the train will permit. Since the cars
short out the signal, running backwards or off the mainline is limited
to 15 mph. When the locomotive reaches the signal at the yard limits,
another code is sent to put the system into "non-cab" mode. This allows
operation up to 45 mph inside the yard or on branch lines where there
are no signals. (The signals inside yard limits at Jax and Hialeah are
ABS signals, not CTC, so they are not part of the system.) When leaving
the yard, the first time a cab signal code is sensed puts the system
back into "cab" mode.

J.L. Hollahan              jlhollahan@webtv.net
Plantation, Florida