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Wednesday, May 14, 2014

Fire! Fire! Help Me! SS28, New Haven Line

Usually when fire comes up in the context of railroad signaling it;s usually some old wooden interlocking tower or relay plant making use of lots of cotton wrapped wires, but more often than one would think modern metal relay huts catch fire and cause all sorts of headaches for the railroad that owns it.  Well a few days ago a fire broke out in one of the instrument houses serving a complete 4-track crossover on the Metro-North New Haven Line (it's really not their year is it).  The interlocking in question is technically known as CP-219, but the proper designation is SS28 GREEN and for those of your who don't know your New Haven Line interlocking here is a photo of what control the interlocking up into the 1980's.

Fortunately the tower was spared as all the relay logic was moved across the RoW to a series of huts connected by cableways.  Now in some of its interlockings MNRR has installed Halon fire suppression, but Connecticut has not opted to pay for such features, however the extreme cheapness did have some benefits as the use of multiple, small relay huts kept the fire contained to a section of non-vital relays used for CTC code line communications.  Now the only reason I am talking about this is because Metro-North was nice enough to post up a whole set of photos on Flickr in the interest of transparency.

As you can see these aren't the familiar glass cased vital relays that would be both costly and time consuming to replace.  Instead these are non-vital elevator/telephone type relays used in the CTC control elements.  Without any damage to the real interlocking local control can be used if necessary and from the service advisory delays of only 5-10 minutes were encountered at the time of the incident.

Not sure if MNRR is going to try to restore the same functionality or just use some infinitely more simple form of modern technology.  The latter would seem obvious, but since it would probably require a brand new custom interface between the non-vital and vital elements I suspect they'll just bring it back exactly as it was.  Note the worker with the old wet dry vac already putting a "restore" plan back into place.

MNRR didn't stop at photos, they also produced a video outlining their little whoopsie.

Anyway, fires happen all the time, but few are so well documented in a way that can shine a light on the inner workings of modern(ish) interlockings. Which reminds me...if you travel the New Haven line late at night instead of looking to the south side of the tracks where the fire was, look to the north because inside the tower a single bulb still burns illuminating the original interlocking machine which fortunately did not burst into flame during its 60 years of operation.

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