Eastern Railroad Discussion > Signal placement question

A question for you signal experts out there - - -

​Attached photo is of the recently installed eastbound NS signal at CP Girard,
​in Girard, PA.. At this point, movements can proceed on the main, or diverge
​into Girard Siding.   I had expected it to be on the same side of the track as the one
​it replaces.  From my observations, this left side placement is not typical, but
​there are other instances. 

​Question for the experts:  What are the guidelines/circumstances which determine
​left vs. right side placement on a single track main such as this ?

(Side note:  photo taken from Rt 18 bridge - wonder how long it'll be before someone
​attempts to get onto the signal from the road ?)

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Sometimes MAYBE more visibility around a curve or other obstruction otherwise, at least out here in CO where they have been putting up replacement signals on main one of the Joint Line between Littleton and Palmer Lake, there seems to be not rhyme or reason (logical anyway) as there are replacement signals on one side with signals for each direction, a signal on each side replacing a single signal, they completely removed one signal with no plans for replacement only to put in a new one a few weeks later?
JB

before I believe 1984 mainline block and interlocking home signals had to be on the right of ths track it governed and if there was a NEED for the signal to be placed on the left the location by MP or interlocking name of that signal had to be listed in the special instructions part of the BOOK OF RULES TIMETABLE ... after that date signal placement on the left was up to the discretion of the railroad without specifying any particular location
..

I thought I heard it said one time that it corresponded to the Man in the right hand seat of a locomotive?

I think currently, in lieu of any other mitigating factors, they just put it in the most convenient spot to get the job done.

Murphy's Law says, it's about time for them to widen RT 18 and have to move that new signal

steve_misky Wrote:
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> Murphy's Law says, it's about time for them to
> widen RT 18 and have to move that new signal

Heck, even just replacing the existing bridge with no widening will be a challenge. 

Signal engineering is a whole class in itself these days.

Typically everything is to a plan, and (hopefully) quite a bit of thought is put into everything based on existing communications, need and territory.

A few years back one of our tracks was converted to all new signals (existing infrastructure went back to the late 1940's). Some signals were essentially placed in the same location, some went to the other side of track and all were "back to back".

For the most part, they went out and determined the best placement and angle for maximum practical visibility.

Sometimes certain installations are just different for maintenance or unannoced future projects so that later trackwork is already considered into the design.

The hardware (essentially) is pretty cheap. Moving communications lines and all the electronics - not so much. Back in the day with all the relay based and hardwiring had to really been a deciding factor for most of anything (labor was cheap!)

FWIW when they did our upgrade I was able to snag some signals and equipment. All the signal guys said the relay based stuff was the best if there was an issue. Replace relay, life was good.

Today it's plug in a laptop, find the bad card, attempt to fix or hope you have a replacement and reprogram.

Maybe someone on a signal gang can chime in.

Looking at the original pic, they *may* just installed it in order to keep what appears to be a control point in service. Sometimes the new CP lights are installed behind the orginal one and the cutover is pretty quick.

Sometimes installing most of the hardware is the priority while awaiting the new doghouse equipment. AFAIK, most are built to order, so lead times may be a factor.

Signal masts and heads are typically a "stock" item.



Edited 1 time(s). Last edit at 11/28/16 21:06 by MW810.

Out_Of_Service Wrote:
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> before I believe 1984 mainline block and
> interlocking home signals had to be on the right
> of ths track it governed ...


Before 1984. Cajon Pass CTC project in 1972 featured field side signaling.

I sometimes wondered about this too.  On the CSX Old Main Line under B&O CPL's they always had two signals, one for WB and one for EB.  When CSX upgraded, in many places they put one pole up with heads on both sides for EB and WB so the signal is on the left side of the tracks depending on which way you are headed.  I just figured the CPL's were from the steam days where the engineer would have limited visibility to the left side and nowadays that is no longer an issue.

Other thing to remember is that crews have to qualify on track they run over.  Part of that qualification is knowing signal placment and which signals govern which tracks.  There are rules, but there are also exceptions.  I suspect that the viaability suggestion is probably correct.

> before I believe 1984 mainline block and
> interlocking home signals had to be on the right
> of ths track it governed and if there was a NEED
> for the signal to be placed on the left the
> location by MP or interlocking name of that signal
> had to be listed in the special instructions

No such mention in the SFe LA Div Spec Instr--
field-side masts over Cajon starting in 1972.

Did CNW and DMIR ever list their left-of-track
signals in the spec instr?

GCOR addresses what track signals govern. Essentially state right hand running. There are provisions if there are two tracks and one signal, the use of a doll arm with a blue light.

If it's single track, not a big deal. If 2MT, then the signal on the field side governs that track. Really not all that hard.

Any out of the norm would be listed in the subdivision general orders.

Perhaps the lack of "high-nose" locomotives in use by virtually all Class-One's had some influence, but also there still is the occassional "long-hood first" movement that would have to be considered, so...