Discussion related to commuter rail and rapid transit operations in the Chicago area including the South Shore Line, Metra Rail, and Chicago Transit Authority.

Moderators: JamesT4, metraRI

  by ExCon90
The latest issue of First & Fastest has a photo of the outer ends of the platforms with dwarf signals displaying red, with two white lights in a horizontal row above; the white lights do not appear on other signals farther into the interlocking. Does anyone know the significance of the white lights, and what other aspects there are? I remember the C&NW dwarfs with a red semaphore arm painted on a white disc, and the last time I was there they had what appeared to be B&O-type position-light dwarfs, but I haven't seen these before.
  by qboy
Its called a starting signal. It basically tells the engineer that its the first governing signal leaving out of OTC. Theres also a white star on the back of the signal head for when trains are beyond the signal the Engineer can look back if the star is light up you can proceed to the next signal after verbal authority from Lake St.
  by ExCon90
Thanks. Do the white lights change to another aspect when the dwarf clears? Also, since UP is in GCOR, are the dwarf aspects Lunar (or Flashing Lunar) = Restricting, Yellow = Approach, and Green = Clear?
  by qboy
The white stars don't change its just tell the engineer its their first governing signal. All the pot signals or dwarf signals they are all absolute signals...they are all restricting signals with in the Lake St. Red= stop...Yellow= restricting approach...Green=restricting clear. There are no lunar or flashing red indications within the interlocking.
  by ExCon90
Thanks again. Looks like it's all on the engineer until he gets out of the interlocking.
  by qboy
Yep! Once Lake St. Tower gives you the line-up and signal its up to the Engineer to follow whatever route they are given.
  by train2
Restricting clear, that seems like a contradiction in terms. How is the indication worded in the rules?
  by qboy
train2 wrote:Restricting clear, that seems like a contradiction in terms. How is the indication worded in the rules?
Proceed at restricting speed not to exceed 10MPH.
  by ExCon90
While this wouldn't ordinarily be in an ett, does anyone know whether it's the practice to display Restricting Clear when the next signal is Approach or better, otherwise Restricting Approach? (Although it still seems illogical, since Restricting means I Brake For Animals; i.e., if you're running at restricted speed it doesn't matter what's on the next signal--you're concerned with what's between you and the next signal.) I remember reading when they put in a second track on a portion of the line to Antioch they established a new aspect at the beginning of 2 tracks called Diverging Clear Approach Diverging, which is a contradiction in terms: if it's Approach Diverging it's not Clear. I think the aspect was R/*G*, a departure from the rule that a flashing aspect is supposed to be more favorable than the equivalent solid aspect. I've wondered whether any of that has changed since.
  by justalurker66
A different rule book that doesn't apply, but NS signals define a green dwarf as SLOW CLEAR, which is 15 MPH until clear of the interlocking. Not the "I brake for animals" speed of restricting (which includes being able to stop within half of the length of vision for defects, etc) but a signal that says the track is clear until the next signal. The NS yellow dwarf is SLOW APPROACH, which is 15 MPH until clear of interlocking then approach next signal prepared to stop. (NS/Conrail signals - and this isn't a rules test so please forgive that the descriptions are not exact quotes.)

I agree that "RESTRICTING CLEAR" is a bit odd ... but if they want to include the "restricting" aspect of looking out for defects/etc it makes sense.
  by EricL
The reason why this interlocking is all-restricted speed is because the signals do not convey track occupancy. They only convey authority - that the operator has you lined up on some kind of valid route. You could have a green signal and have another train/engine right past it, ahead of you - if you both happened to be heading toward the same place. Even your last signal before entering the final station track is green.
It's an unconventional setup for sure, but it's been that way "forever".
It feels weird to disregard the concept of blocks when that's what you're doing the whole rest of the time. But I guess C&NW must have made it that way because it's a very complex interlocking with a lot of routing possibilities, packed into a very small space. Write the restricted speed requirement into the signal indication rule rather than go to the trouble to physically display it on the signals.