Eastern Railroad Discussion > Clear to Next Interlocking or Controlled Point signal

There has been some discussion recently on how NS plans to remove the physical intermediate block signals between Pittsburgh and Harrisburg, relying instead on cab signals. I have some questions regarding the NS "Clear to Next Interlocking or Controlled Point" signal, whose aspect is a white C over a flashing lunar white light. (It's also found on other former PRR/Conrail territories, such as the Northeast Corridor, and simply called "Clear to Next Interlocking".) The purpose of this signal is pretty clear: it allows trains without operative cab signals to proceed on an absolute block to the next interlocking signal.

1. When the dispatcher establishes an absolute block and requests this signal, does the signal system actually first perform a logical check of whether any block is occupied between the Clear to Next Interlocking signal and the following fixed signal? Keep in mind by "block" here I am actually referring to those blocks between interlockings that are not actually marked by the presence of a fixed signal (but are still blocks used by the cab signal system).

2. If the signal system does indeed perform the logical check described above before displaying Clear to Next Interlocking, then does this mean that Clear to Next Interlocking can only be displayed beside a fixed signal displaying some variant of "clear", including slow clear, medium clear, and limited clear? (Let's assume in answering this question that the interlockings are not too close together, so that the first interlocking signal's indication is not dependent on the status of the next interlocking signal's indication.)

Thanks for any responses! I've been curious as to the story behind this signal for some time.

To further confuse things a bit, I can find lots of photos on the Northeast Corridor of the "C" portion of the signal lit (associated with a variety of fixed signals, including Stop Signal)... but not the full "C" over flashing lunar. So what does the "C" alone indicate, if anything?

DivergingClear Wrote:
-------------------------------------------------------
> I can find lots
> of photos on the Northeast Corridor of the "C"
> portion of the signal lit ... but not the full "C" over flashing
> lunar. So what does the "C" alone indicate, if
> anything?

Maybe the flashing lunar was "off" at the moment when the shutter was clicked?

DivergingClear Wrote:
-------------------------------------------------------
> There has been some discussion recently on how NS
> plans to remove the physical intermediate block
> signals between Pittsburgh and Harrisburg, relying
> instead on cab signals. I have some questions
> regarding the NS "Clear to Next Interlocking or
> Controlled Point" signal, whose aspect is a white
> C over a flashing lunar white light. (It's also
> found on other former PRR/Conrail territories,
> such as the Northeast Corridor, and simply called
> "Clear to Next Interlocking".) The purpose of
> this signal is pretty clear: it allows trains
> without operative cab signals to proceed on an
> absolute block to the next interlocking signal.
>
> 1. When the dispatcher establishes an absolute
> block and requests this signal, does the signal
> system actually first perform a logical check of
> whether any block is occupied between the Clear to
> Next Interlocking signal and the following fixed
> signal? Keep in mind by "block" here I am
> actually referring to those blocks between
> interlockings that are not actually marked by the
> presence of a fixed signal (but are still blocks
> used by the cab signal system).

It better, or that "C" indication isn't worth much.
"Clear to Next Interlocking" means exactly that, there are no impediments to movement between this location and the next.

> 2. If the signal system does indeed perform the
> logical check described above before displaying
> Clear to Next Interlocking, then does this mean
> that Clear to Next Interlocking can only be
> displayed beside a fixed signal displaying some
> variant of "clear", including slow clear, medium
> clear, and limited clear? (Let's assume in
> answering this question that the interlockings are
> not too close together, so that the first
> interlocking signal's indication is not dependent
> on the status of the next interlocking signal's
> indication.)
>
> Thanks for any responses! I've been curious as to
> the story behind this signal for some time.

I've only ever seen it displayed in conjunction with a proceed indication, but my experience with it is quite limited, having only seen it displayed twice between Pittsburgh and Cleveland via Alliance.

NZ

Here's an example, CP66 on the Cleveland Line just south of the Fort Wayne Line crossing in Alliance, Ohio.

daniel

---

One can find a video online that shows "Clear to Next Interlocking" displayed with an Approach on the fixed signal. The possibility of the fixed signal showing an aspect other than something with "Clear" in its name makes sense since it would depend on local conditions (e.g. lengths and number of blocks to the next control point). Since it's rare that control points are so close together though, and since you couldn't have a preceding train in between, I'd say you're usually going to see it with a Clear, Limited Clear, Medium Clear, or Slow Clear.

As for the second question/post, I thought some of these signals had an illuminated "C" rather than just a painted one, but I haven't seen one of those myself to know if it is always lit or if it illuminates only with the flashing lunar.

I cannot speak specifically to the ex-CR lines, but I do work in cab signal territory elsewhere.

Also being from that neck of the woods, ill but my 75% accuracy on this.

With railroad rules, defined by FRA regulations, it’s obvious that those running on cab signals can proceed based on can signal display.

However, if cabs fail in CS territory (which is typically, not always CTC), the dispatcher will issue “absoulet block”.

To my knowledge, this is a FRA deal. Each block signal becomes an “absolute signal”.

For a train to pass a signal displaying an indication that requires stop, restricted speed or similar, the train must stop. The train then must contact the dispatcher who must acertain that the block ahead is clear of trains or other on track equipment, etc.

The “clear to next interlocking” signal, as I understand it in territory that has intermediate signals removed, operates this same way as a green or yellow intermediate signal would - but now it’s essentially a reallllllly long block. If lit, your good to go.

If not lit, then dispatcher permission would be needed.

The signal system itself still operates the same way - it checks for occupancy and route. If it detects an occupancy between CP 1 and CP 5, it should not light that light (back to permission).

Whenever we have a cab signal failure, we space ourselves far behind the train ahead so we do not need to stop and talk to the dispatcher.

The NORAC rule essentially reads the same as GCOR:

Trains with inoperative cab signals, automatic train stop, or speed control must proceed on fixed signal indication (and cab signal indication, if operable) not exceeding 79 MPH. Trains with inoperative cab signals must approach the next home signal prepared to stop, unless Approach Normal (Rule 280b) is displayed on a distant signal prior to the home signal.



Edited 1 time(s). Last edit at 06/15/18 19:36 by MP683.