On another thread I just learned what a doll mast was, and remembered dwarf signals. Rather than hijacking that thread, I thought I’d ask here. What is the reason dwarf signals are used instead of full-sized signals? Is it just cost? I’m assuming that the dwarf signals, unlike doll masts, display various aspects similar to full-height signals.
In the Perris line improvement thread, there was one photo where there were dwarf signals between two tracks. The caption stated that the dwarfs were used (instead of full-height signals) due to clearance issues.
Chuck
Paul of Covington (3-16):
Hi Paul,
Yes, tomikawaTT made reference to clearance issues.
For the most part, dwarf signals are going away, except for issues as above. On Union Pacific, another issue seems to have arisen.
The above CP is at Casa Grande, AZ on UP’s Sunset Route. At that location is a mismatch of turnout speeds, 30 M.P.H. vs. 50 M.P.H. In those situations, UP seems to utilize the dwarfs for 30 M.P.H. routes, and regular masts to 50 M.P.H. But, that doesn’t seem to be a hard and fast rule.
Best,
K.P.
Dwarf signals are generally signals which are low, to the right of the track direction, and are usually for reverse movements as home signals at interlockings or switches and often show only two aspects: stop and caution. In some instances low signals may be full authority signals and located low because of clearances and are so designated in timetables and instructions. I believe the term “dwarf” used to be restricted to how I describe it above but today any signal not on a mast or at least engineer sight height above the track is considered a dwarf.
Some do, some don’t. It depends on the railroad. Pennsy’s true position light dwarf signals* could at best display a “slow clear”. While on the Reading side of things, you could get a regular clear out of a dwarf (double greens). Since dwarfs are mostly used coming off branches, industrial leads, sidings, dark lines, or in conjunction with running opposing on tracks signaled one direction, you wouldn’t need a full clear in speed-based signals (NORAC). As Henry noted, some dwarfs out there can only display stop or restricting.
*But Pennsy also had the “domino” signals if they wanted full speed aspects in a limited amount of room.
I believe they actually prefer to be called “little signals.” [(-D]
Actually, more rails probably call them “pot” signals instead of “dwarf” signals. I know that’s the term used around my area and discussions on other forums/lists have rails from other areas and railroads using that term.
Jeff
As we learned in the discussion of ‘stones’ - different areas have their own nomenclature for common things.
And then there are blind signals.
Actually they are “Blind Stops” : Locations where there is a tripper but no signal head.
Most annoying are the WD signals. These signals located low like dwarf signals detect the speed of your entire train as it passes the signal. This Lunar signal has 3 aspects: Dark–It is asleep and will not bother your; ON–It is watching you: maintain correct speed (posted) until “End WD” placard; or FLASHING–It is on and it is mad at you: slow down at once or be stopped by the tripper.
ROAR
Lion - where are these in use?
You usually find blind signals on rapid transit lines, especially in subways, where the curve to the right blocks out visibility of a signal so a “blind” or “repeater” will be place on the left side tunnel wall. You can no longer see them in operation because the motorman’s cab is no longer a closet on the right side of the car facing the direction you are travelling but is full vestibule wide cutting off the view we grew up with. I know they are in use on NYC subways and PATH. I think there are similar situations on regular railroads which would be identified in their employee timetables and rules books.
Wheel Detectors are more and more common. When you ride the front of the train look for the yellow placard with the letters WD and a speed number on it. There will be a signal there which may be dark or it may display Lunar. These are usually associated with diverging routes and would only be active when a restriction is in place. Ten cars down the road or ten cars past the restriction another placard will be the “END WD”
As for the blind stop, I am not sure where they are (they are blind, after all) but I am told that they are associated with certain grade and station timers.
ROAR
K.P., that is certainly an interesting track arrang
Informative discussion.
I had always assumed that dwarfs were generally used in slow speed situations where overhead/lineside signals would be impractical. That would be places like large passenger stations with “puzzle” track configurations.
Interesting to see some other applications.