New signal on the Northern Main - North Chelmsford / Tynsgboro

[Skybug]

Been a while since I have been on here so I thought I would reach out and see what folks think. I live right near the Northern Main line that goes to NH. I live near CP4 and there is a light signal along the tracks about a 100 yards or so down the track from the nearest road intersection. It's an old one, been there for many years. Just a round one with 2 lights, red and green and has been in use. Now, and just noticed it, there is a brand new light tree structure and control box right near the intersection of the road. Now, for such a quiet line and only one track, all that's ever on it is local runs, maybe 20, 30 cars to Nashua, once in a blue moon, a coal run will pass thru. For such a quiet, seldom used line, what would call for such a more, advanced light signal unit. It's going from a 2 light, round head to a 10 light system. This one has (3), 3 lights and a single round one with 1 light. Is this quiet line destining to become active again? From what I can ell from a distance, I believe the old one is round, didn't want to go down the tracks to get closer, it is small and only ever seen reg or green lights, or no lights on at all. The attached pictures are whats down the track and been in use and the new one right at the street that has 10 lights now. It's turned so the lights are facing across the tracks so its currently not in use right now. Thoughts anyone? Frank

[newpylong]

Can you provide some context of exactly where this is? There is no CPN-4 on the Northern.

[GP40MC1118]

New "Approach Restricting Signal" at MPN 12.92 for southward movements. Does not convey
block and track information. I guess its the Distant Signal for North Chelmsford.

[Skybug]

There is a CPN4, the track runs right along the river where live and the stone marker is in clear view by the track where I am located. CP3 is down where this new unit is located, down by the North Chelmsford/Tynsgboro line on Middlesex Road (aka Rt 3A). Its single track thru this area, just saw a PanAm go by with a bunch of them grey, slurry type cars heading to Nashua.(so that image of the small light unit at ground level is not in this area, its just an example of the one down where this new unit is located, but its mounted on a pole) Check out this link, page 108. https://www.regulations.gov/document?D= ... -0068-0002 I just remembered I had a book from years ago that showed the entire system and all the control points, now I have to find it.

[pnolette]

CP means Control Point.The stone markers are Milepost,or MP. So your near MPN4

[Skybug]

I'll have to take another look at it. I heard it called one thing by the dispatcher but I see what you saying. I just found my book, its outdated but so is this line here. Its a nice book, shows all the line points, yards, etc. ( just took a ride, the post I see has the number 4 on it, so I assumed it was CPN4, I have heard the dispatch call it both ways. We learn everyday, so the CP "control point" these would be where track switches, etc are located I presume? and the MP would be just mile makers. I reading thru my book now for this area.)

[Skybug]

Can you provide some context of exactly where this is? There is no CPN-4 on the Northern.

Ok, now that I learned a little here, this new one is located at N2.70, I'm located near N4.11, also, according to the book, Shows a [D] meaning DCS Station (NORAC) whatever that means.

[newpylong]

D means it's a distant signal to an interlocking. You're in CTC territory.

[Skybug]

D means it's a distant signal to an interlocking. You're in CTC territory.

Ok, that would probably mean the Nashua yard then. Will be interesting to see if and when this new light system is put into service. Looking at the control box it will be a while. Can see the input connector on the side of it where I would think wiring will go into. Thanks

[newpylong]

Other direction. That would be the distant to CPN-1 in North Chelmsford.

[gokeefe]

Quite a surprising place for investments. Anybody have a guess as to why?

[S1f3432]

In your original post you mentioned an apparent increase in complexity because of the increase in the number of lights.
The old style "searchlight" style signal heads displayed up to three color aspects through a single lens. Inside the signal head
was a relay mechanism which contained a pivoting blade in front of the lamp with three color aspects- red in the center with
green and yellow to either side. When the relay was energized normal polarity a selenoid pulled the blade to one side so
the green aspect was in front of the lamp. Reverse the circuit polarity and the blade was pulled the other way so the yellow
aspect was infront of the lamp. With no power to the relay the blade hangs dead center with the red aspect in front of the
lamp and in theory makes it failsafe. However, mechanical linkages have been known to fail even with the required
government inspections and tests. Another liability is vandalism with broken lens fragments falling back into the enclosure
and preventing movent of the blade. Both situations can cause false signal indications leading to fatal outcomes. When I
worked as a signal maintainer 30+ years ago the railroads were being pressured by the FRA to replace these types of signals with
color-light type signals which only contain a lamp, reflector and lens with with no relay or moving parts to fail. So what you see
in the new signals is an individual lamp head for each color- 3 for 1. In the photo, where there might have been two search-
light heads one above the other, there are now two color-light heads each with three lamps. While it may appear more
complex, from an installation and maintenance view point it is much less so. Hope this helps.

[S1f3432]

Searchlight Signal Mechanism and Aspects

[gokeefe]

I never realized that searchlight signals had these vulnerabilities. It makes perfect sense of course.

[Engineer Spike]

I didn’t know that FRA was requesting replacement of searchlight signals. My company has been redoing controlled points with LED color lights. A maintainer told me that the old relay logic of the old searchlight installations was not PTC compatible. A few years ago they did upgrade two CPs because of a second siding across the main from the existing one. These plants have searchlight signals. I find it odd because they had been using the fiber optic signals which look like fake searchlight style. Fortunately, they have been going to LED. The fiber fake searchlight signals are very hard to see in the daylight.

As to the aspects inside a searchlight head, sometimes they have lunar instead of either green or red. When I was on BN, ex Q, most signals were searchlight. Restricting was indicated with a lunar aspect. In some places where the signal also had to be able to display a green and yellow aspect, a flashing red was used instead.