I'm throwing this in the SP forum because whatever knowledge is gained here will be applied to our club layout which models SP lines in Donner, Tehachapi, and the Cal-P. Hopefully there are some old SP hands who will enjoy answering these questions? (I'm also open to hearing about stuff involving other railroads if it seems at all relevant.) Here are my questions... 1) I found this 1996 SP timetable section online. I note that this is from a "Central Region" timetable, but I don't know exactly what that means. Would these rules have applied in California? 2a) I note that there are no dwarf signals in the timetable, but I know that SP used dwarf or "short mast" signals on routes we model. (e.g. siding signals in Tehachapi pass.) Would the height of a signal ever have had any significance on the SP, as it apparently did on other railroads? And where would SP have used dwarves? At yard entrances or exits? Industrial spurs? 2b)A related issue: based on what I have gleaned and deduced from other sources online, it seems that SP signals were purely a "route signalling" system. Correct? 3a) Looking again at the time table linked to above... Can anyone explain the difference between the various "Approach Diverging" aspects? What's the difference between "yellow over yellow" and "yellow over green", and where would you have seen this on a two headed signal vs. a three headed signal? 3b) How close would two diverging routes have to be to each other to necessitate a three headed signal? Thanks in advance. We have some complicated spots on the layout I may ask about later. Hopefully we can stop ending our spirited club discussions about those locations with "well, we don't really know what the prototype would do".
Ben, Hi. I have no SP experience (PC/CR/NS Engineer), but this chart (only a page or two of a Timetable) seems incomplete. I believe the host is aware of shortcomings and is soliciting information, too. 1) A region is an operational/organizational segment of a rail system (subject to re-definition by the company). Because of variation in types of operations, geography, etc., Timetables may be issued by Region or Division/Sub-Division to address all Rules commonly used, plus circumstances particular to that segment. 2a) Dwarf (low Home Signals) here are used at Control Points & Interlockings where a route is entering Signaled Track from non-signaled track (yard or industrial track, eg.). Dwarf signals are SLOW Speed signals, so need not be seen from great distance - can be placed closer to the ground. I don't know SP's specifics, but again, a complete Timetable (for your Region/Division/Sub) would be helpful. 2b)Don't know what you mean by the term "Route Signaling...automatic wayside signals convey block condition (occupied/obstructed or not), and at Interlockings/CP's and approaches - speed restrictions and route information (Diverging move, speed within block/CP/Int., etc., for the entire train). 3a) the different "Aspects" of the diverging signals probably indicate max speed authorized through diverging switches and within the limits (between the extreme opposite "Home" signals on the route used) of the Int./CP -the chart references other information elsewhere. I've run out of my depth (and SP-relevant info), so I'm Quittin' Hope some of this helps, and that my lack of SP-Smarts hasn't led you all astray...just tryin' ta Help. Bob C.
Hi Bob, thanks for the response. About dwarves and route signalling... I'm aware that on most eastern roads dwarves are used for slow routes. For example, you can see this type of terminology in the Bessemer and Lake Erie timetable on Carsten's site. However the SP timetable doesn't use this type of terminology. (Neither do any ATSF, UP or BNSF timetables I've seen.) Earlier today I read this well written article on signals by Al Krug. He refers to route signaling on 'some roads', and says that on such roads '...for instance, instead of red over green being [called] Medium Clear, it is DIVERGING CLEAR. Since the SP timetable uses that kind of terminology, I deduced it is what Krug calls a route signaling system. I also read somewhere that the Caltrain commuter rail here south of San Francisco switched from 'route signaling' to 'speed signaling' a couple years ago. Since this was SP track until the 80s, I assumed the old signal system was the old SP system. I understand the signals I have observed on the Caltrain better now that I've read Krug's article. It is probably now similar to the systems you're familiar with.
The dwarf/low signal implies that there is a "dummy" marker head (red) above. It allows the "red over X" signal indications to be displayed without having the expense and maintenance of the actual top red signal. You would read a dwarf/low signal as if the top red is present: a green dwarf signal is actually red over green or "diverging clear." FYI the "dummy" marker head of a dwarf/low signal works the same for route signaling or speed signaling. Jamie
OK, kinda get the "route signal" thing...here a "Medium Clear" means you are diverting (through switches rated at 30mph) through the CP/Interlocking and "Clear Signal" when entire train is through the CP limits..."Slow Clear" = 15mph; "Limited Clear" = 40mph, (sorry, don't know what switch number = what speed). Your qualifications may tell you which route you're lined for at a complex CP, with differing switch angles/speeds or exit routes/speed limits/operating rules. Here's a NORAC (Conrail & other Northeast RR's) signal card ;http://www.railroadsignals.us/rulebooks/cr88/cr88.htm for comparison and definitions of the system I was used to...may shed a little light. Bob
Does this imply that dwarves would not be used to protect the trailing point of a crossover or a spur on a main track (because that would not be slow route)? Would such a situation always be protected by the block signal even if it were some distance further back? And what about in yard areas? In the situation this most pertains to on our club layout, we have a double track main passing through an area with yards on both sides, a passenger station, and several crossovers. I don't have a lot of evidence of how SP used dwarves back in the day, but here's one example. I think that dwarf protects the two turnouts (one for the foreground track and one for the crossover a bit down the track) but I'm not sure.
The dwarf in the foreground appears to protect the left track in the opposite direction of the train passing in the photo. It could be controlling a move from unsignaled track, from a "reverse" move, if that track has an assigned direction (as the train is moving right to left), or could be an "intermediate" circuit within a CP/Interlocking allowing short reverse moves. Signals USUALLY are to the right of the designated track, unless clearance prohibits, though this convention is less followed than formerly. All opinions, of course - and from the Eastern perspective. Bob C.
the shot you used in your second to last post that dwarf is for the first crossover and it would also be your signal entering CTC. Note the tall mast signal says begin CTC. So the dwarf is there for that track as a standard signal wouldnt fit there. Most dwarf signals for western roads are placed in yards and in spots like this. Where you need a signal and a normal signal woud not fit.Its rather odd though as you look towards the far end in that pic and there is a cantilever Santa Fe signal at the far end but not at this end. I am assuming Santa Fe signal rules apply here so you choices would be Clear,approach, diverging clear, diverging approach,restricting and stop. Not sure if you would have some of the other ones here. SF has a few oddball ones like a flashing green over yellow ( IIRC) which is you slow to 60 it is before an approach medium which is 45 then approach 30 but if the guy in front of you is flying like most SF trains then you never see anything more restricting.Used on the transcon and its one that makes BN guys scratch their heads lol.
Duh, I should have remembered that. I think the only time one can deviate from this convention (aside from overhead placement) is by putting a signal for a left-most track to the left of it. In this case, the dwarf would have to be for the left track, or it would be ambiguous.
Thanks, this is useful info. At the club we'd like excuses to use dwarves so as to have fewer signals sticking up for bumbling club members to knock over. Would it be reasonable to guess that the reason for the dwarf instead of a signal bridge is that the track behind the photographer is double-track, so a reverse move on the left track would be rare? IOW, why put in a bridge for a signal that engineers will rarely be looking at? (As opposed to the opposite end of the CP, where it's CTC so trains are more likely to be approaching on either track.) Actually the picture is in the town of Tehachapi so it's actually SP track, and rules I would assume. ATSF (and now BNSF) of course have had trackage rights forever.
Well it looks done up right for a CP. I am going to show my ignorance but is there ABS on the way up to this signal?But whats messed up I jsut started thinking about the Transcon for some reason and seeings its 2 main track ( non directional running) we had signals with heads on both sides ( except at control points you had one coming into the CP then you saw the back of a signal on the way out of it as you dont need another one that soon)But the arangment would have allowed it to be on the outside of the rail not inbetween tracks so now this is kinda an oddball deal. Dwarfs at the end of a siding works well too. We use them on the DM&E ( Former IC&E RI) south end of Cotter has one yet the north end has a mast type signal as it is on the engineers side and no need to worry about it being in the way.
