On a railroad signal what are the uses for signal heads that are 3 over 3 over 2?

Question

A friend and I are making a train layout that takes place in the coal fields in the eastern US. This means we will be using NS signals from N&W to the modern ones. Anyway I am designing a custom made signal system to fit the region ( this is going to be hard for a 14 year old, I know) and train layout perfectly. That is why I need answers to this question.

Answer 1

each signal typically designates movement on one track, so for instance the top head might mean for a main track movement, the middle one for a diverging main or siding and lower one might be for movement into a yard or industry track.

There are so many variations in signal systems from company to company and from subdivision to subdivision.

Even somethign as simple as a red signal, should mean STOP right?

Not necessarily, it can mean stop, or stop and then pass at restricted speed, or simply pass at restricted speed.

YOu really should try and get a timetable from the territory you are trying to replicate. those are available quite readily.

Answer 2

Not sure about your specific question,  but in light of your project,  these may be helpful......

http://gsee.sdf-us.org/signals/siglinks/...

http://mysite.du.edu/~etuttle/rail/sigs....

http://mysite.du.edu/~jcalvert/railway/r...

http://www.geocities.com/CapeCanaveral/L...

http://www.railroadsignals.us/

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

Answer 3

These signals are used to signal trains that they are going to proceed on a "diverging route."  Example:  You taveling on the main track and the train dispatcher wants to put you into the siding.  With a signal with two signal units, you may receive a "Red over Green" aspect.  In essence, it is saying RED (stop) for movement on the main, GREEN (proceed) on the diverging route.

Where there is a third route controlled by this signal, then you would see "Red over Red over Green" or other combinations of aspects to govern your movement accordingly.

But, there are signal masts with multiple units that do not govern movement to a diverging route.  These govern the APPROACH to the signal governing movement on the route to be used.  Using our original example, you would likely see a "Yellow over Green" aspect, meaning be prepared to proceed on diverging route not exceeding speed of the switch involved.

I know.  Kind of complicated, but there ya go.  Good question.

Answer 4

The "proper" signal configuration is 3-over-3-over-3.  Like Hog (SkidderBack) said, the top signal is basic information, and the lower one or two signals are for diverging moves, and also denote speed.  The middle group tells you to move at "medium" or "limited" speeds (less than 45 MPH in most cases), and the bottom group is for "slow" speeds (around 15-20 MPH max).  So, if you get (from the top) a red-red-green, it means to divert at a slow speed until your entire train has competed the diverging movement and is clear of the switches, and then the track is clear ahead and you can keep going as fast as you can.  This signal can be called "Slow Clear."

In some places, it's impossible to get a Slow Clear.  For example, you may get a situation where your train can go onto a siding, but 1/2 mile ahead there is another signal, for a bridge or siding or something (like the entrance to a railyard or a wye going to another rail main line), and the next signal is always going to be a Slow, or Stop, or something less than a full Clear.  Therefore, the first signal can never give you a Slow Clear because the track ahead is never really Clear - there's always something ahead to watch out for.  In this case, it's silly to include a green light in the lower cluster of the first signal, since it will never, ever be used.  So, the rail companies will order the signal without the green light in the cluster.

Sometimes, in the case of a siding with a slow-speed switch or something, it is possible for the trains to go either full-speed (straight) or slow (to the siding).  A medium speed is not ever given, so the middle cluster will not have the green light, and maybe not even the yellow light.