• Some info on FEC's cab signals

  • Discussion relating to the FEC operations, past and present. Includes Brightline. Official web site can be found here: FECRWY.COM.
Discussion relating to the FEC operations, past and present. Includes Brightline. Official web site can be found here: FECRWY.COM.

Moderator: GOLDEN-ARM

  by Jadebenn
I did some digging on the matter and managed to procure a February 1988 copy of Railway Age that had an article about the matter (FEC: System-Wide with ATC).

At least as of the original installation, the FEC system used a carrier signal of 40 Hz, and their installation of the Harmon signal system was known as Ultra-Cab 40.

Speed control was accomplished by comparing a braking curve to the actual speed and determining and a "time to application" before penalty braking would be applied. I'm not an expert about train signalling systems, but that sounds a lot like modern PTC.

There are more details in the article itself, and I wish I had a better understanding of the actual subject matter so I could convey them to you better. I legally can't upload the file, but I can use it to try and answer any questions you might have.
  by Engineer Spike
Freight locomotives running on Amtrak and Metro North, like NS, CSX, D&H, and Guilford have the Harmon system. It is called Locomotive Speed Limiter, or LSL. It did prevent speed violations. I’m sure that LSL was a later addition to the cab signals on the locomotives. It would be interesting to find out. Cab signals have been around for almost 100 years. Back then there was a rash of accidents, as locomotives and trains grew bigger and faster. There was a federal mandate for cab signals or automatic train stop, just like the present PTC mandate. Over the years railroads got wavers to discontinue many of them, partially due to passenger train discontinuation. Pooling power was also difficult because the leader would have to be changed to a home road unit, unless both roads had a compatible system. Before the merger, UP and C&NW had non compatible systems. They had units with both systems. During my BN tenure, I was on the suburban trains. The Metra F40s had a key switch to change between Burlington, Rock, I’m not sure if Milwaukee had it, but also C&NW cab signals, and their ATS.

The difference from PTC is that the slowest LSL protects to is restricted speed. A train with LSL can get approach signal, but fail to stop at a stop signal. PTC also protects against failed crossing warning, work zones, and main track authority on unsignaled lines. Most of all it prevents a stop signal from being passed. It does so by taking the train braking power, line grade, and figures out a stopping distance at each speed. On the line where I work there are a few downhill spots with a stop signal. With a heavy train, one must really creep down to the signal.
  by WhartonAndNorthern
Any idea what the cab signal aspect codes are/were? This document suggests there were 8 aspects.

I know PRR-style was 4 aspects (no code, 75 ppm, 120 ppm, 180 ppm) and the LIRR added 270 ppm and 420 ppm.