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On my daily commute, I pass two of what I call PRR-style signals that span double-tracks for the Boston to Fitchburg MBTA commuter rail heading west.  I believe the signals have one light per track. One signal is for the block before the Concord station and the other is for the block before the West Concord station.  I like to see what colors or combinations the lights are between the two stations and try to anticipate where the train is.  In the last month, instead of having a (usually) steady red as a "default" state, the signals are now totally dark -- only periodically showing red, green, or yellow.

Further down the line just before the Ayer junction station is a U-shaped signal with three lights on each arm (see attached photo).  This section of the double track is shared by the MBTA and Norfolk Southern/Pan Am.  Normally, all six lights are red the majority of the time.  I've seen the top right one turn green as a commuter train approached and immediately turn red when the train hit the block; and once I saw one on the left side turn yellow when a NS freight train was backing up into a siding.  Nothing surprising there; other than that all six lights are always red. 

But this signal has also gone completely dark in the last month.  I've been noticing these signals for two years and am puzzled at the new behavior (clearly I need to "get a life" ).  It doesn't seem terribly safe to have no indication of what's going on in the block ahead or on the other track.

Can anyone shed some light on this new signal behavior?  (For what it's worth, several miles before the Ayer station are dual lights set on angled arms, one for each track, which I believe set off a short block for an industry siding.  By contrast, they are always lit even though the siding isn't used anymore.)

Thanks,

Tomlinson Run Railroad

 

 

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  • Signal at Ayer MA Junction in 2014: It's hard to see, but all six lights were red in 2014.
Last edited by TomlinsonRunRR
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These signals may be operating under Approach lighting (NOT to be confused with APPROACH ASPECT), where the signals are only lit when a train enters the block preceding the signal. The reason behind approach lighting is to reduce the electrical demand, and prolong bulb life, by not having the signal lit when there is no one to observe/obey the signal.

  There is nothing unsafe about this, if a train was to approach the signal, and it was not lit, the engineer would be required to treat the signal as if it was displaying it's most restrictive ASPECT. If the dark signal was an ABSOLUTE Block signal, the train would be required to STOP short of the signal.

Doug

Doug,

Thanks for the background.  I wondered if it was somehow a cost-cutting measure, even though the fares just went up again.  It makes sense to read that safety rules exist for approaching a truly unlit signal. 

If a signal only lights now when a train is approaching a block, I'll have to keep that in mind and note more closely which colors are for which track during my next 10-second "Where's Charlie" commuting game. Of course the best days are when the train is actually on the track I'm observing, but that's pretty rare.  

Thanks again,

Tomlinson Run Railroad

P.S. - "Saves on electrical demand and bulb life", humm, it sounds like approach lighting was made for model layouts :-).

A little off topic but this one would come up in rule classes every now and then.

You're  on single track  CTC territory and  have a green (clear) approach signal(single green). When you get to the home signal ,the bottom light is burnt out.   You now have a green over a burnt out light. Stop or keep on going?

Ace posted:

Would it only be older signal systems in some locations that have signals lit all the time? Because"approach lighting" seems like the norm to me for most places.

BNSF's 3 track Chicago-Aurora mainline signals are lit all the time due to traffic density.   The whole system was upgraded about a decade ago from searchlight signals to three color signals:

W Springs 090709 14

Rusty

 

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  • W Springs 090709 14
Gregg posted:

A little off topic but this one would come up in rule classes every now and then.

You're  on single track  CTC territory and  have a green (clear) approach signal(single green). When you get to the home signal ,the bottom light is burnt out.   You now have a green over a burnt out light. Stop or keep on going?

I'm not up on all the specifics of operating rules, but I would suppose that a light not illuminated should be treated the same as a most restrictive indication. In this example you would proceed at reduced speed expecting the next signal to indicate stop or diverging route ?

On the original subject, I would expect constantly lit signals to be used only on heavy-traffic lines with frequent trains, which is a minor portion of total route mileage in the USA.

Last edited by Ace

I know the lights are always illuminated in CTC territory at least with CN  right across Canada, However I have noticed the lights on CP close to where  rail are not always lighted.  It's not CTC but maybe ABS or an occupancy block system  (a easy system almost like train orders).    I have a couple of spots that I check to see if the lights are lighted or not so I might want to watch a train... If the lights go out, the train has gone.

Yep ACE... rule 27. you got it. A signal imperfectly displayed or the absence of a signal at a place where one is usually shown must be regarded as the most restrictive indication that can be given by that signal. In this case it would a STOP.    A burn out bulb would indicate a imperfectly displayed signal.

I remember once on NS going east, down the mountain, into Altoona when all the signals went dark.  We had to stop at every signal.  Man, that seemed to take forever to get our coal train down that hill.  To keep our train under control to be able to stop at every signal we had to crawl from one signal to the other.  If I remember correctly those signals are every mile.

Rick

I was on a BNSF office car trip between Houston and New Orleans in the late 1990's.  An ice storm had hit the entire region bringing down power lines and disabling all the wayside signals and grade crossing protection.  We moved at restricted speed, stopping at every dark signal as well as at every road crossing equipped with gates and or crossing signals.  The train had to be flagged over each of these crossings.  The powers that be finally said "enough" around Crowley, LA and put all of us onto a bus headed straight to the New Orleans airport.

BNSF subsequently scheduled a "make up" office car trip that ran from New Orleans to Houston without incident.

Curt

RICKC posted:

I remember once on NS going east, down the mountain, into Altoona when all the signals went dark.  We had to stop at every signal.  Man, that seemed to take forever to get our coal train down that hill.  To keep our train under control to be able to stop at every signal we had to crawl from one signal to the other.  If I remember correctly those signals are every mile.

Rick

I'm glad I wasn't your head end brakeman....Did you also have to take all duel control switches OFF power,  making  sure the gears were messed  and lined for the proper route and then put back on power after the leading wheels of the engine were on the points?    No a big problem with one switch but on double or more tracks perhaps 5 switches might have to taken off power to get by one signal.   

Must be a NS thing. I cross the NS Southern Tier line on the way to visit my parents and there's a signal a few hundred feet South of the crossing.

One of the few times I saw the signal green was when Rich and the 765 was mere minutes away last year. Shortly after that the signal went dark and has been ever since. I only saw it lit once recently immediately after a train had passed.

In Southern California, UP and SP used approach lighting on their signals and - when a train approached - lighted both units on 2-unit (2-"head") signals, while Santa Fe signals were continuously lighted and the bottom unit of a 2-unit signal was dark, unless required for a particular aspect to be displayed.  Red over dark, flashing red over dark, yellow over dark, flashing yellow over dark, and green over dark were legitimate aspects and the Signal Aspects and Indications page of the ATSF rule book showed them.  Santa Fe signal practice was somewhat independent, so . . .

The FRA suggested to ATSF that every signal unit should be lighted when an aspect was displayed, and the Santa Fe, knowing that an ignored suggestion would be followed by an order, wisely volunteered to light all signal units.  At the same time, ATSF standardized on modified approach lighting.  All automatic signals were dark until their approach circuits were occupied.  Controlled signals were dark until the Dispatcher lined a train through that location, at which time the signals at that control point became illuminated in both directions.  This was referred to as Intent Lighting by the ATSF Signal Dept.  On the former ATSF portions of BNSF, that is still the normal practice, except where traffic is so heavy that continuous lighting is used.

Well, the signals were apparently lit and working on this northern branch of the MBTA commuter rail but that didn't stop this truck from running through the crossing arm earlier today. Although in fairness to the driver, a medical emergency hasn't been ruled out. Luckily, all passengers were OK. It's a pretty riveting video:

http://m.wcvb.com/news/driver-...ickup-truck/41153320

TRRR

Last edited by TomlinsonRunRR
KOOLjock1 posted:

PRR style?  

Jon  

Hi Jon,

What I was trying to convey was the shape of the armature, not anything related to signal aspects.  For some reason I was under the impression that the Pennsy was the first to install those inverted U-shaped signals that straddled two  or more tracks and with lights on disks. So, when I see one of these structures, I think of the PRR, even out in the wilds of Boston and Maine country :-).  I could be wrong as to my "facts" as I can't remember where I got that impression from.  An operations book or accessories catalog maybe?

TRRR

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