Signal Complexity

[rkcarguy]

Apparently my area was all CTC, according to some google searching.

[Steggy]

What did I miss? I could have got permissive and absolute mixed up?

A signal being permissive or absolute is determined by the road's signalling rules, not how it's wired into the circuit. Most roads identify a signal as permissive by affixing a number plate or a G-plate to the mast or supporting structure. Conversely, the absence of a number plate or G-plate, or the presence of an A-plate identifies the signal as absolute.

I'm at a bit of a loss of the definition of each type of system and how they work relatively. From what I have seen in real life operations, viewing a signal (as a southbound train would), I would see these aspects displayed on the signal as traffic came north into town.

There isn't nearly enough room on Chaski to give you a proper explanation (also, the time required to do so would be considerable). As always, the Internet and a good search engine (where "good search engine" basically means anything other than Google or Bing) are you friends. Here's a website that gives a good explanation of North American signalling practice. If you spend some time reading the material it should make a lot more sense to you. However, the site doesn't get into technical specifics with regards to circuitry, etc.

The interesting thing is, the signals on the UP sub along the Deschutes river in Oregon would stay green all night long even void of traffic. The ones in my hometown, would go dark unless there was activity in the area.

On many lines, approach-lit signals are used to conserve lamp life and reduce quiescent power consumption. Lamp life is much less an issue since LEDs were introduced to full-sized signalling. However, approach-lit territory in which incandescent signals were retrofitted or replaced with LEDs often remain approach-lit. LEDs, while long-lived compared to the 7500 hour incandescent lamps that they've replaced, still have a finite lifetime (~100,000 hours when not driven too hard), so retaining the approach-lit setup makes sense.

[Erskine Tramway]

To expand a little on BDD's explanation, an Absolute signal is generally at a location (a Control Point, or OS) where there are remote controlled switches. They would include crossovers and junctions. The 'Absolute' part means that you Absolutely cannot pass a red signal until you have specific authority from the Control Operator or Dispatcher. Absolute signals can be set up to run automatically by the Control operator, as when he puts the CTC on 'Fleet', to run more than one train, but generally they are manually controlled through the CTC machine. The Intermediate signals between two Control Points are automatic, controlled by track circuits, and can be Permissive.

On the BN, we had two-headed signals at the 'entering' end of a Control Point. The top light controlled movement on the 'straight' track, and the lower, movement diverging through the turnout.

I have some AAR and ICS signal books, and the wiring for bi-directional running gets pretty complicated.

Mike

[rkcarguy]

What did I miss? I could have got permissive and absolute mixed up?

A signal being permissive or absolute is determined by the road's signalling rules, not how it's wired into the circuit. Most roads identify a signal as permissive by affixing a number plate or a G-plate to the mast or supporting structure. Conversely, the absence of a number plate or G-plate, or the presence of an A-plate identifies the signal as absolute.

I'm at a bit of a loss of the definition of each type of system and how they work relatively. From what I have seen in real life operations, viewing a signal (as a southbound train would), I would see these aspects displayed on the signal as traffic came north into town.

There isn't nearly enough room on Chaski to give you a proper explanation (also, the time required to do so would be considerable). As always, the Internet and a good search engine (where "good search engine" basically means anything other than Google or Bing) are you friends. Here's a website that gives a good explanation of North American signalling practice. If you spend some time reading the material it should make a lot more sense to you. However, the site doesn't get into technical specifics with regards to circuitry, etc.

The interesting thing is, the signals on the UP sub along the Deschutes river in Oregon would stay green all night long even void of traffic. The ones in my hometown, would go dark unless there was activity in the area.

On many lines, approach-lit signals are used to conserve lamp life and reduce quiescent power consumption. Lamp life is much less an issue since LEDs were introduced to full-sized signalling. However, approach-lit territory in which incandescent signals were retrofitted or replaced with LEDs often remain approach-lit. LEDs, while long-lived compared to the 7500 hour incandescent lamps that they've replaced, still have a finite lifetime (~100,000 hours when not driven too hard), so retaining the approach-lit setup makes sense.

The route along the Deschutes had a lot of slide area's with rock fences, I think the idea was that if there was enough of a slide the rock fence would drop the block signal to red, therefore the reason while they were on all the time?

[johnpenn74]

John, could you enlighten us as to what relays you are using?

Rkc,
The relays are nothing special DPDT from Mcmaster. You can use singles, but for what they cost you can buy the doubles. I am trying to build my system using only electric parts (relays, lights and resistors) similar to the prototype APB system from 1911 or so. All of the switching I am doing to run the lights is via the relays. 2 relays per head, (Red, Amber Green), 1 relay for track detection. The prototype actually used other stuff, like polar relays but that is beyond practical costs.

On my set up, I setup the relay logic so Red indications are NC and Amber is also NC; Green is NO; that is nomally closed is the more restictive state. Per the prototype, the signal comm is hard wired where a hi signal = a clear block for both the home block and the distant block. This is also needed if you are going to have the intermediates tumble down.

Simplicity is a relative thing. If one has enough electrical know how to run a meter and use a test light then he should be able to trouble shoot the system. No PLCs, no proprietary hardware, no software, no laptops. Simple electrical wiring like it was a hundred years ago.

You can make a really simple non safety, 3 light head that will give you Home and Distant indications. It start getting complicated when you try to get the tumble down or trailing lights working (stick relay) but that is over kill for now.

If you want to learn more about prototypical signal wiring, let me suggest you get a copy of "Introduction to North American Railway Signaling, 2008, K Bisset.

JP

[johnpenn74]

Another question for the professionals....
In my neighborhood (Augusta, Ga) I have seen several mainline CSXT signal heads that have 4 lights; Green Amber Blue and Red. The lunar is used few and far between but when it is, it is used to indicate a main line switch (with throw detector) to an industry. My question, is this, does the safetran standard replacing permissive with blue? This is the obvious case when switching off the main to an industry, but I wonder if this is happening anywhere else.

[Steggy]

The relays are nothing special DPDT from Mcmaster.

Those are kind of on the expensive side, no? Also, they consume quite a bit of space and power.

Another question for the professionals....

In my neighborhood (Augusta, Ga) I have seen several mainline CSXT signal heads that have 4 lights; Green Amber Blue and Red. The lunar is used few and far between but when it is, it is used to indicate a main line switch (with throw detector) to an industry. My question, is this, does the safetran standard replacing permissive with blue? This is the obvious case when switching off the main to an industry, but I wonder if this is happening anywhere else.

That I can't answer for you. I'm not familiar with CSX's signalling rules.

[rkcarguy]

John,

Ok you've done it the same way I have then, green is normally open @ both relays in the pics I posted.
The relays I'm using are these 5 packs of automotive relays off of Amazon for $12.99. They have plugs with pigtails that can be slipped onto a tab so they can be mounted yet easily changed out.

So to signal my RR properly, lets say I have two headed signals at each end of a passing siding. With the turnout thrown to diverging, the train approaching would first see a distant signal displaying amber? and then the two headed signal would show a red over yellow. Likewise, the distant signal would display a yellow, then display green once the oncoming train cleared onto the siding? I will not have a high speed diverging route, so I have omitted green from my lower signal heads.

[Erskine Tramway]

Another question for the professionals....
In my neighborhood (Augusta, Ga) I have seen several mainline CSXT signal heads that have 4 lights; Green Amber Blue and Red. The lunar is used few and far between but when it is, it is used to indicate a main line switch (with throw detector) to an industry. My question, is this, does the safetran standard replacing permissive with blue? This is the obvious case when switching off the main to an industry, but I wonder if this is happening anywhere else.

That's interesting, John.

I've never seen a 4-light signal. On the BN, the Lunar indication is called 'Restricting', meaning 'Proceed at Restricted Speed'. It is usually used at locations where you were leaving CTC for unsignalled track. In our case all the mine leads were unsignalled, so you'd come in on a Lunar. At places, like Eagle Butte Jct., where there were two diverging routes, you would get a low Lunar, but until you could see the switch points you couldn't be sure whether you were lined into Rawhide or Buckskin Mine. You knew where your train was 'supposed' to go, but, being Restricted Speed territory, you still had to be prepared for the points being wrong.

Your explanation sounds like CSX is using it for the same thing at unsignalled industry tracks. It would only be used where there was a 'power' switch off the mainline. A hand thrown switch would give you a Red signal when it was open. Do you know if the switches are power operated?

The situation I'm most familiar with is at Rozet, Wyo., where the hand throw switch into the Rozet 3 and 4 tracks off the mainline, is a couple car lengths West of the signalled crossovers. If the switch is open, the crossover signals would be Red, and you'd have to get talked into the block to use the switch. Usual practice, if you are going to use a hand thrown switch, is to get at least one set of wheels past the entering signal to the block, before you open the switch.

Mike

[johnpenn74]

RKC

Yes, these run of the mill ice cube relays. About $20 each for the base and relay... not cheap but that's the cost of standard din rail mounted industrial components these days. Following industrial practice the relays and bases are standard and easily replaced when broken. I like this stuff cause, well, that's what I do for a living and so I lean to familiar, heavier parts. Eaglepoint is a lightening rod, and we keep getting lightening strikes. The last one blew up some of the Integrated Circuit boards and cat 5 wire between signal heads. The general theory is the track is inducing a current during the strike and the lightweight stuff couldn't handle it. Granted enough lighting on a direct hit will kill most anything, but I feel what we have used in the past is just too light, Cat 5 22AWG and IC relays. I'll go a step further and say something like 16AWG and standard industrial components have a better change of survival. Not to mention there is code that governs the size and components; NEC, NFPA, etc...

So to signal my RR properly, lets say I have two headed signals at each end of a passing siding. With the turnout thrown to diverging, the train approaching would first see a distant signal displaying amber? and then the two headed signal would show a red over yellow. Likewise, the distant signal would display a yellow, then display green once the oncoming train cleared onto the siding? I will not have a high speed diverging route, so I have omitted green from my lower signal heads.

Sure that sounds correct. Remember there is a difference between speed signals, route signals, and how a railroad displays each based on their rules.

For example: route signals on Southern Railroad in Georgia would have two heads, upper is the main line route and the lower is the alternative path. Where as ATSF or maybe SP (I think) would have 2 head semaphore where the top head is showing advance indication (one block away) and the lower signal is showing the home indication (immediate block). Both route, but the head are configured completely different.

For this signaling project I decide to go the route signals and not speed signals. I figure route is better since the operators know where they want to go and can judge how fast to go by themselves.

Lastly remember color indication is ALWAYS showing occupancy. When the block is occupied its red, when the next block is occupied its yellow. Even a speed signal shows occupancy when the route is diverging. Red, Yellow and green are not a traffic light, they are occupancy indications. I would think the Yellow over red on your block would go red over red as soon as the train is in the block. (Maybe)

JP

[BAdams]

Though I am a HUGE fan of McMaster-Carr, have you guys tried sourcing your relays through some of the surplus electronics suppliers?

All Electronics here in SoCal comes to mind, here is a link to the relays they currently have available: https://www.allelectronics.com/category ... ays/1.html

There's Electronics Goldmine out of Scottsdale AZ as well:
https://www.goldmine-elec-products.com/ ... ?dept=1114


Just a thought.

Brook

[rkcarguy]

That's good I seem to have it right, thanks John.
I'm modeling the Eugene, OR area, where SP regularly used their S12's to switch and serve lumber mills and other industries in the 60's-70's. I have plenty of pictures of the types of signals used, and the SP signal rule book the was posted online, but hadn't actually seen any video of the signals going through their paces per various conditions like you can find now. (Train mountain video, and there is one of a head on collision that you get a cab ride view of the signals as a BNSF approaches a siding and was supposed to take it to pass an oncoming train but the oncoming blows the stop!).