Signal Bridge Lights?????

[Anonymous]

Can you people help as to what the signal lights mean on a real railroad, either on a bridge or trackside post or dwarf signal ??? Thank you Steve[?][%-)]

[Buckeye Riveter]

Guess what Steve? On different railroads the lights mean different things. Of course there are the basics, red = stop. Several years ago I stood alongside the tracks in Berea, Ohio and asked one of our company's railroad engineers what the lights mean and he told me that it depended on many different factors and in this particular case it was multiple tracks and what company controlled the interlock.

John from NE Ohio may be able to shed more light on this subject. I would also like to know more about the signals.

[wrmcclellan]

Steve,

Check out this link - lots of good stuff on this subject.

http://www.du.edu/~jcalvert/railway/railhom.htm

Regards,
Roy

[csxt30]

Well, only limited knowledge on signals. First, if a crew goes through a red signal, they're imediately taken out of service, taken to hospital for drug tests, & that means all the crewmembers. They usually get back to work in a month or so, but they are strict on that one. They have yellow signals which may mean a restricting speed, I think it means slow, but then they have a medium approach signal & of course Red always means stop. Green means a clear block ahead. In some instances they may have a red dwarf, going back on the main, & get verbal permission from the dispatcher to go back out on the main & permission for a reverse move also they need, if tying back onto their train, after picking up in the yard or setting off. They go by a book of rules, which they get tested on each year by the FRA. Safety is most important. Also , most of our signals are off, till a train gets a block or 2 away, as We some times may be working near a signal & see it light up green & know a train will be coming. This saves on the bulb when not much traffic. Signal systems vary on each RR, though. My job doesn't require me to know signals, though I am fascinated with them. Thanks, John

[Buckeye Riveter]

John, the Ohio Central is running their trains without trackside signals. Can you give a brief explanation on how they are doing it? I know they use the radios extensively.

[csxt30]

They may be using the horn or whistle, along with the radio. There are hand signals we used years ago ,& if it was at night they, would swing the light. Also they used flares, then there were the torpedos, an explosive pack they would secure on the rail behind them, so an oncoming train would run over it & it went off to alert them a train is ahead. Well off to work today for a double , 16 hrs. Talk to ya all tomorrow night, thanks, John

[wrmcclellan]

Buckeye,

No signaling is called "dark territory." The crew is equipped with radios.

When no signaling is present they operate on movement authorities. The dispatcher secures the crew an authority to occupy certain sections of track (denoted by mileposts or control points - i.e. switches). The authorities are communicated via radio or in writing. Everything on the radio is confirmed by the crew by reading it back to the dispatcher. The RRs have a written rule for how all numbers are read over the radio so there absolutely no confusion. Once a series of movements are completed or the time period of the authority expires, the crew must secure a new authority for their next movement. If something not covered by the authority comes up, the crew must get explicit instructions from the dispatcher and a change to the authority. If a signal or control point is overrun, they must get dispatcher permission to back the train up.

Track where trains number around 1 per day or less are rarely signaled. About half of US trackage is dark. Almost all new signalling and control is being done with wireless. Even in yards where the tower is adjacent to the tracks.

I had the privilege to work on the AAR's wireless standards committee for a couple of years. I learned a lot from a great group of engineers and the C&S guys (Communications and Signaling).

Regards,
Roy

[Buckeye Riveter]

Roy, when they say in-cab signals, what exactly is that all about?

[wrmcclellan]

Buckeye,

The in-cab was invented by either the NYC or the Pennsy. Pulse coded signals are injected onto the rails, which are insulated for each block (hey - just like toy trains!). There is a current sensing receiver (via axles) in the locomotive that reads these signals and then lights a red, yellow, or green light in the cab - mounted near the engineer. The lights denote speed limits. Today, the system has been expanded to 9 lights (aspects) for finer control - particularly for the Acela - up to 150 mph.

You will notice many in-cab photos of F units will show the box with 3 lights on it to the right of the engineer and mounted near the windshield.

Here is a link to a current manufacturer - notice the interesting cab view of a B&O style position light signal.

http://www.phwinc.com/products.htm

Here is another interesting site for signaling.

http://broadway.pennsyrr.com/Rail/Signal/

Regards,
Roy

[lionelsoni]

There are lots of subtleties and exceptions in signals; but generally a 3-aspect automatic signal shows red when the block after the signal is occupied, yellow ("amber") when that block is unoccupied but the next one is occupied, and green when there are two clear blocks ahead. A train may usually pass a red signal at a very low speed, but only if the signal has a number board, indicating that it is an automatic signal.

At a point where tracks diverge, as at the entrance to a passing siding, there will probably be two signals, one above the other. The upper signal is for the main line, the lower one for the diverging path to the siding. One signal will always be red. The lower signal will have only two lights, yellow and red, since the train would not take the diverging path at high speed.

An unlit signal is treated as a red signal. Oftentimes signals are dark until some event, such as an approaching train or a dispatcher's action, lights them up.