The IRSE...

... Institute for Railway Signal Engineers (England) states that:-

This document is very interesting and is available here:-

http://www.irse.org/minorrailways/publicdocuments/PA01%20-%20Mechanically%20Operated%20Points%20v2.pdf

Obviously this is British practice but I would think it would be similar in the USA.

The PRR used a lot of Electro Pneumatic installations for larger and/or busier locations. these were electrically controlled but pneumatically operated and could longer distances from the tower. I can't find a spec for this though.

Signals (mechanical) of course can be a lot further from the tower as they are operated by a wire and require much less effort.

Interlockings

Differentciation between "junction" and "switching".   Switching (classification, industry work) will most likely NOT be part of an interlocking. Too slow and cumbersome.

An interlocking would be where you want somebody to set up higher speed moves that would create a route without stopping a train to line switches or where one railroad/route crossed another.

Another question I have is

Its the 1950's.  They have electricity, pole lines and CTC.  The other interlocking could be controlled remotely by the first tower.  The more complicatred interlocking might be the "Armstong" one and the simpler one the remote one.

If a person controls the switches and signals, then its a "manual" interlocking.    "Hand" operation is when the train crew lines the switches themselves.  In the rules any time they say "hand" operation, its the train crew.  There is no differenciation in the rules between an Armstong and a electric/electro-pnuematic interlocking or between an interlocking that is right where the operator is or where the operator is 1000 miles away.  Same rules.

Thank you

Dave and Graeme, the information you have provided is quite valuable.

Dave, if electric controlled devices were installed for the turnouts at the other end of the station/town wouldn't the prototype rip out the Armstrong levers and replace the entire station?

It would rather defeat the purpose of what I am trying to do, which is to have a few locations using Armstrong Levers.  And I did not accurately describe the track arrangement I am trying to have.  The idea of having a Tower Operator is to allow for the traffic to move faster as the P&A crosses over several Class 1 Railroads and there is "heavy" traffic on both lines.    In two cases on my layout, the P&A provides trackage rights for two other railroads through two towns (it enters in one town, and exits another).  In each of those towns there will be a tower operator to deal with the junctions (the physical tracks that are under the towers control is referred to as an interlocking, correct?).  There's another town that has the foreign railroad only cross the P&A mainline and there is an interchange track (see the other thread about hiding tracks to see how I hope to have actual trains from the foreign railroad come onto the layout, interchange cars, and then continue on to other staging).  Now with that crossing, there needs to be a tower to control the signals correct?  From what I have read, if I am understanding it correctly, if the traffic is busy enough, a human operator needs to be at the controls (whether it's in a tower or at a control center with a CTC Maching) to control who has clearance for the diamond crossing. 

I realize I could have CTC control all of this, but I find CTC to be "boring" (For those that love it, I am not saying CTC is wrong, just for me it's boring) and I find TT&TO and Tower operation to be much more interactive and interesting to do. Many railroads still had many sections, if not their entire system still using TT&TO and towers, so I don't feel it's out of place.  Still, I want to make sure I use them appropriately. 

So since I would like the P&A to remain "Dark", I'm not sure if I can have turnouts controlled by electric/pneumatic machines because if they had them,  then logically the old Armstrong Levers would be torn out.  Or did other railroads do that?  

Before Electric/pneumatic controls  what did the prototype do to control the turnouts at the opposite end of a station with a tower?

Thanks again!

Ken L.

Towers

What are you asking about?  What are you considering the "station"?  The tower, the building, the place, the track arrangement?    For example in Texas, pretty much all major railroad crossings are called "towers" regardless of whether there is a building there or not.  there has been a tower building at Tower 55 in Ft Worth for maybe 100 years.  It hasn't been occupied for at least the last 30.  Its controlled by the dispatcher near Houston or in Omaha.

Why are "armstrong" levers so important?  What difference do you think they make?  the only physical difference that would be visible on  the layout is the rodding.  Other than that they have the same rules.

An interlocking is a system of switches and signals arranged to allow moves to be made in succession.  It is the collection of all the switches and signals and tracks they control at one station that the operator controls.

If its a crossing then it could be an automatic interlocking.

You seem to be getting hung up on the need for a physical building there.  A "tower" could be a desk in a one story building.  Tower 74 in Beaumont, Texas is a desk/office in a one story yard office.

Not necessarily.  The famous Rochelle interlocking with its railfan park and web cam is an automatic interlocking.  To tell the truth it isn't even on the UP dispatcher's CTC panel.   There is NO marker of any kind on his panel, there is no control operator and the dispatcher can't do diddley to operate any signal at the interlocking.

The only time you need a human operator is where there will be trains changing routes at speed.  So if there is a junction with one switch (one route splits into two routes) and they don't want the trains to stop and line the switch then there will be a manual interlocking.

If you read interlocking rules and CTC rules they are virtually the same.  CTC and "interlockings" are fundamentally the same.  In CTC and interlockings, signal indications supersede the superiority of trains.

What difference does it make?  Who cares what the connection is between the signal or switch and the operator is?  It make no difference to the rules.  Whether the operator turns a handle, pulls a lever or flips a switch its the same.

Once again, what do you mean by a 'station"?  An intelocking is a "point" (why the CTC equivalent of an interlocking is a "control point").    Are you asking about a siding?  If you have a tower at each end of a siding you have two stations (a station is a place named in the timetable) and two interlockings.

You can have two tower buildings and two operators.

You can have two tower buildings and one operator (controls both interlockings)

You can have two tower buildings and one operator that isn't in either tower building.

You can have one tower building and one operator (controls both interlockings).

You can have no tower buildings and one operator.

What are you asking about? 

What are you asking about?  What are you considering the "station"?  The tower, the building, the place, the track arrangement?    For example in Texas, pretty much all major railroad crossings are called "towers" regardless of whether there is a building there or not.  there has been a tower building at Tower 55 in Ft Worth for maybe 100 years.  It hasn't been occupied for at least the last 30.  Its controlled by the dispatcher near Houston or in Omaha.< <

When I use the word "Tower" I am speaking about the actual building, usually two stories, where the switch control are located

Why are "armstrong" levers so important?  What difference do you think they make?  the only physical difference that would be visible on  the layout is the rodding.  Other than that they have the same rules.< <

There will be a person at a desk and on that desk for these towns "miniature" Armstrong Levers that will interlock.  In reality they will actuate electrical switches that are connected to switch machines, but on the layout it would seem like the tower operator is controlling the turnouts using the levers.

An interlocking is a system of switches and signals arranged to allow moves to be made in succession.  It is the collection of all the switches and signals and tracks they control at one station that the operator controls.< <

Thank you for the correction.

If its a crossing then it could be an automatic interlocking.< <

How would the automatic interlocking know who has rights over the crossing?  With Train Orders being able to overrule the timetable schedule, I'm a bit perplexed on how that would work.

What difference does it make?  Who cares what the connection is between the signal or switch and the operator is?  It make no difference to the rules.  Whether the operator turns a handle, pulls a lever or flips a switch its the same.< <

Because I am trying to replicate in slightly more detail the various railroad jobs.  I will have Operators at the various stations.  Now one person will facilitate more than one job and at multiple stations, station to be location where a local operator will OS the train and report back to the Dispatcher.  Not every station will be open 24 hours, so to make their jobs more interesting, I am adding the role of "tower operator" to their duities.  Now before anyone raises their hand to suggest that is too much to do, my hope is to have traffic density that is more in line with prototype practices vs what is typically found on many model railroads.  The fact that with only one exception, there is at minimum 1.5x the train length distance in between stations, should allow plenty of time for the two people covering the 6 towns to do all of their duties.  So if I have a physical building (tower) to control the interlocking (signals, switches, derails, etc) that is at one end of the station, I need to determine who/what controls the turnouts at the other end of the station at the far end of town? 
 

Once again, what do you mean by a 'station"?  < <

A section of track where an Operator may be located (if the office is open) to receive Train Orders from a Dispatcher to give to train crews and to OS trains as they pass.  A station may or may not have a siding.  Not all stations are towns, and not all towns are stations.  Although a Station MAY be where a town (a local jurisdiction where there is some form of population) is located, that is not always the case, and vice versa.  At least hat is how I am defining them.

An intelocking is a "point" (why the CTC equivalent of an interlocking is a "control point").    Are you asking about a siding?  If you have a tower at each end of a siding you have two stations (a station is a place named in the timetable) and two interlockings.< <

Your definition of Station is in line with mine, though yours provides better clarity.  If a railroad has yet to purchase the technology to install electric/pneumatic controls for turnouts, and is limited to Armstrong Lever technology, how would the railroad deal with the end of a Station where there is an Interlocking at the other end and there is a Tower-man operating the Interlocking "plant" from the two story building?  If the idea is to keep the traffic flowing, and not having to stop, only controlling one end of the station seems rather pointless if at the other end they have to stop to throw the turnout.

Ken L

There will be a person at a

OK, got it now.  You want to use a particular brand of control to operate the switches, etc. and you want the model operation to match the brand of control.   That will limit you to the tower only controlling switches that are some "small" distance from the tower, lets say within 3 or 4 feet actual feet, a couple hundred scale feet of the tower.  Anything more than that has to be hand operated, a spring switch or another tower.

First come, first served.  There are no "rights" over the crossing.  There is nothing in train orders that deals with crossing per se.  There is nothing in the rights of trains that deals with crossings per se.  Superiority of trains is irrelevant at crossings.  Train orders don't "over rule" anything at crossings.  There is no "schedule" at a crossing.  Trains of railroad A have no requirement to clear the time of railroad B at the crossing whether its a manual or automatic interlocking..

If a crossing is an interlocking, then the movements through the interlocking are made on signal indication which supersedes the superiority of trains.

If it s a manual interlocking then the only thing that establishes priority is company policy.  It is the supervisor of whoever is the tower operator telling them that they won't let any train on the other road block the hotshot on their railroad or else.  So what you get there are the circumstances like in Memphis the IC would hold the signal on freight trains hours before Amtrak got there.  there is no rule that requires that, its management policy or the whim of the operator.

If you are making them an intelocking operator then you better make that job 24x7.

Once again we come back to the definition of a station.  A station is a place named in the timetable.  A station can be just a signpost next to the tracks.  a station can have depot or not have a depot.  A station can have switches or just be single main track, a station can have an operator or not.  A station can have a siding or not.  I am still not clear on what you mean by a station.

So I assume in this case you mean "siding" when you say "station".  If its single track, TT&TO operation I wouldn't have anybody control the switches on either end of the siding, well the crew would.  If its a siding, then the only reason a through train would use the switches is to head in for a train meet.  In that case its going to stop anyway so there is no advantage to having a tower.

We seem to have morphed from a junction to just a siding.  A junction would have an interlocking, a siding no.  At most one end might be a interlocking then have a spring switch at the other.  e.g. EWD trains making a meet ALWAYS head into the siding and WWD trains hold the main.

That's how I define a station.

A station is a point, not a section of track.  A block is a section of track.  A train order office is where a train order operator is located, but that may not have anything to do with an interlocking.  Not all train order offices are at interlockings and not all interlockings are train order offices.

Once again definition of a station.  A station is not a track arrangement.  Don't really care about what makes the controls go.

If you have a siding its a siding.  What is going on at the ends of the siding that compels the railroads to spend thousands or hundreds of thousands of dollars a year in salaries and maintenance to put an interlocking there.  Just the siding switch is not a good answer by the way.

You put an interlocking someplace because there is trackwork that involves multiple main track routes and you don't want the trains to stop.  That is not a siding switch.

Once you put in an interlocking , that makes it a station (its a named point).  So if I have an interlocking on the east end, a depot, an interlocking of the west end, I have THREE stations.  Two of them are interlockings and one is a depot to stop and recieve traffic.

If its just a siding, then you are going to stop one train or the other to make a meet.  That's what sidings are for, to meet and pass trains.  If that is the case it doesn't matter what you put at either end, the inferior train is gonna stop.

If you want to keep traffic flowing then you don't have sidings and make it double track, operate 251 and put interlockings at the junctions.

Another consideration you haven't thought of is if you make both ends of the siding an interlocking and you want to make a meet, how do you communicate to the interlocking operator which train takes the siding or even that meet is going to take place there?  Are you going to address every meet to the control operators too?

"If the idea is to keep the

     With a full crew and caboose they just rolled slowly out of the siding then when clear the rear brakeman would throw and lock the switch then run to get aboard then they'd highball the engine. Those old boys knew how to run trains even in the days before radios. :> ) .......DaveB  

How would the automatic

As Dave mentions, it's "first-come, first-served," and this is dealt with in the relay logic of the automatic interlocking. (Whether that logic is actually executed entirely via vital relays or in combination with a vital logic controller, it's still commonly referred to as the relay logic. The logic equations are actually written to show relay contacts, whether actual relays or internal logic bits changing states from 0 to 1 or vice versa.)

When a train enters an approach track to an at-grade crossing, the signal the crews see ahead of them (in approach) is a Distant signal (perhaps approach lit) whose aspect is either green or yellow. (Distant signals, which are indicated by a "D" marker on the mast, do not display red aspects, ever.)

A Distant signal displaying a green aspect = proceed and means the train owns the interlocking; the Home absolute signal at the interlocking will be something better than Red. However, a yellow aspect = prepare to stop at the Home absolute signal of the interlocking, because another train is occupying or is about the occupy the crossing.

The distance between the Distant and Home interlocking signals is established based on the safe braking distance required. Remember, in dark territory, maximum authorized speed is 49 mph. The operating department may have put permanent speed restrictions in place two or more miles before the approach track circuit to the interlocking.

In some applications, the senior railroad's D signals will display either green or yellow aspects, while the junior railroad's D signals will always display only yellow aspects. Again, yellow = prepare to stop at next signal, "prepare" being the operative word. The junior railroad may also have a slower maximum speed and thus a shorter distance between the D signal and the home signal. This would tend to tilt the first-come, first-served idea in favor of the senior railroad.

Looks like I will need to add some complexity...

Based on what is being explained here, it looks like I will have to make the trackwork a bit more complicated to have to justify having an interlocking plant that is manned by a someone that is open 24-7.  I realize the prototype would try to make things simple, but since this is an aspect of operation that I want to include on the layout, I will need to come up with a track arrangement that makes sense and is plausible.  I will need to do more research on this.  Thanks everyone.  If there is anything else that should be added please do so as I would like to have as much information as possible.

Thanks again!

Ken L

1) Would there be more than

Are all three legs main tracks?  How far apart are the switches?  What is the speed on the wye legs?

General comment, model railroaders are horribly frightened by stopping a train.  Real railroads, not so much.

General comment : this would be better as a separate thread or as a new comment on the bottom of the existing thread.  Making it an addendum to the original message just means the readers have to scroll back and forth 10 messages to read a response, look at the diagram, read more response, look at the diagram.

Wrong.  There is no siding at this station, The P&A there has two main tracks.

No the whole idea of an interlocking is to control the order of the movements to avoid collisions.

No, it just makes it unwieldly and distant.  The question is how far away is it on the "real" railroad?  100 ft or a mile?  Yes an interlocking goes at the crossovers and it will control the 4 crossover switches and maybe the freight house switch since its is rather unfortunately located in the middle of the interlocking (VERY unweildy).

Depending on the rules, many railroads say you can't reverse directions in a control point or interlocking if you only occupy part of the interlocking without verbal permission of the control operator.  Under those rules every single move switching the freight house would have to be done with the permission of the control operator.

Why worry about it.  You want Armstrong levers, so don't even consider electric or pnuematic switches.  Then the only consideration is how comfortable do you feel with the distance.  Is it 100 ft or 1000 ft?  If its 1000 ft then there have to be two towers, each a different station. 

By the way here is what the track looks like to the two different railroads.  As modelers we tend to helicopter over the railroad and don't actually see it from a railroad's point of view.  (oops realize after I posted it your RR is the P&A, not the PY&A, sorry).  Modelers tend to overcomplicate things.  For example few modelers realize that the Rochelle interlocking on the web cam doesn't even appear on the dispatcher's board.  Most automatic interlockings don't.  As far as the dispatcher is concerned there are just two main tracks.

Oops, just noticed the crossovers are reversed too. 

Those views are the views that would be in a timetable or a profile map.  The interchange yard switches would be hand operated as would any industry tracks.  Neither the freight house nor the team track is accessible to the NYC.

Armstrong and electric

Hi, Ken. 

You are getting a lot of info . . some of it confusing. ---- As an operator on the IC RR, I worked many towers, some with NYC, even. By your layout's era, here's how it was at Armstrong interlockings: 

1. Some towers still had switches near the tower rod-connected.  Signals by then were electric. Switches at end of The. siding were Armstrong near tower, other end of siding controlled from the tower . . called the "low voltage" as the switch and signals were powered by batteries. The levers in the tower mainly operated an electrical switch, rather than rodding.  This was important because they interlocking machine still prevented conflicting movements. 

2. Some towers also had the big levers operating electric power switch machines . . . especially for crossovers. I also ran some big complicated interlockers with electric everything. No

I like the rodding and have added it to my layout's interlocking. Main point is, you can mix rods and power icely, and prototypically.  BTW, wire control of signals in the US went away fairly soon, changed to rodding, which would be changed to power by the 50's. 

Skip Luke. 

Retireded Railroader

Priorities at crossings

Automatic interlocking are indeed first-come, first served. Not so true at manned towers. The operator works for one of the railroads; when there is a conflict, especially between "your railroad" (who signs your paycheck,) and the "other guys" you have to help your own line if it is a close call. Esp. when it is psgr vs freight. You do not want your railroad's Trainmaster bawling you out because you laid out the Panama Limited for a drag on the crossing line. 

Long rodding distances depend somewhat on how good the signal maintainer is. I worked a tower where it took "a man and a boy" to throw the siding switch. Next tower up the line you could tthrow the corresponding switch with one hand! 

Skip Luke 

So in somce cases...

....an electric turnout would be controlled by an armstrong lever, so instead of the lever physically moving the rod for the switch points, it was an electrical switch to control the switch points? Am I understanding you correctly Skip?  The idea here is I am trying to incorporate the use of Armstrong Levers in the towers.

Thanks for the additional info!

Ken L.

Thats right...

...Ken. Towers a long way from a turnout often had the rodding replaced with an electric or electro-pneumatic turnout motor to make it easier for the operator especially in bad weather. the lever was still used as it was connected to the interlocking. I have seen whole towers (signal boxes in Australia) where all the turnout are electric but the Armstrong levers are still used.

Quite often a box would be removed and controlled by an adjacent box and they would put in a small auxilliary panel to control the distant box but the local panel was still Armstong.

Interlocking levers

Yes, Graeme said it right. The big Armstrong levers remained in service but operated an electrical switch for switch motors and signals.  The interlocking machine itself remained in service. If you aren't familiar with that, there are  some good documents on the Internet. 

Skip Luke

I model the IC at Centralia,

I model the IC at Centralia, IL in 1955.  Looking at the special instructions in an employee timetable I found this:

14. Following code of whistle signals will be used in calling for interlocking signals:

Centralia,

For southward main                                     -

From southward main to yard                      - o

From yard to northward main                      -

Did the engineer use these signals when he was ready for the operator to open the switch?  The switches from the north and south mains into the yard would have been a mile or more from the yard office so the must have been electrical.  I do see some phone booths on the property map and there are instructions for M&I trains (trackage rights on the IC through Centralia) to get permission from the dispatcher in Champaign 120 miles north, through the Centralia passenger station, before entering the IC main. This is about 5 miles north of the yard at Branch Junction where the Illinois Division meets the St Louis Division, Centralia District. The property map shows phones where the yard tracks meet the mains.

It seems to me that considering 4 railroads operated in town right on top of each other, that whistle signals for an operator to open a switch into the yard would be pretty confusing.

My other question is; was the interlocking plant always in a tower?  None of the property maps or track charts I have for Centralia shows a tower in the yard complex.  The ETT shows the standard clock and Train Register for the yard was located in the "B" yard office.  Would the interlocking plant have been located there?

The only tower I can find in Centralia was one jointly operated by the CB&Q and Southern where they crossed the IC mainline a mile or so north of the yard.
 

Jeff White

Alma, IL

some Towers...

....aren't what you think of as a tower. Sometimes they were just a small building like a yard office and the "tower" could also be  in another building such as a depot. The tower in Grand Central Station is actually 5 floors underground!

Did the engineer use these

Don't confuse the yard with the interlocking.  Where where the interlocking limits?  An interlocking is a very defined set of switches and signals and there are specific rules that apply only within those limits.  It reads like its is in double track (rule 251 territory).  I would take it that the interlocking was on the north end of the yard and the yard was on the west side of the tracks.   The interlocking controlled 3 switches, a switch in the SWD main into the yard and a trailing point crossover north of the yard switch.  There may have been other railroads crossing the IC but they would be irrelevent as far as the whistle signals went.

Obviously the interlocking operator had to be close enough to the interlocking to hear the whistle signals.

The whistle signals only applied to the IC at that interlocking so confusion is probably not a problem and if the operator was adjacent to the interlocking then the train would pull up to the interlocking, blow for a route, the operator would line the train and the train would proceed.

Another option would be for the IC to install a "Charlie McCarthy" at the interlocking, basically a microphone with a speaker in the operator's office.  the operator would see the train step on the approaches to the interlocking and then heare the call for signals.

The Katy used Charlie McCarthy's at several closed stations to let the dispatcher know when a trian was passing.

No, the interlocking is the track.  The operator can be anywhere if the interlocking is electric.  manual interlocking now may have the operator 2000 miles away in a dispatch center.  The train register and standard clock have nothing to do with the interlocking, all that tells you is where the crews went on duty.

Another follow up question

OK, for this town that I have drawn a diagram, we have a double track mainline (the Erie RR) and a Single Track Mainline (the P&A).  I didn't draw in the bridge in the diagram but this is another bridge crossing, that the P&A originally had, and the Erie needed to cross the river, and Erie Management decided it would be cheaper to approach the P&A to have trackage rights over the P&A.  Part of the deal, though, is this section of mainline through the town is double track, and the P&A agreed.   Now here are a couple questions. 

The P&A would control the two interlockings at both end of the town.  Would the P&A go from one track to two then and cross like this diagram to keep the direction of one track East(Erie)/South(P&A) and tge other track west(Erie)/North(P&A) like so?

 
The Red is the Erie RR, Black is the P&A, Purple is Erie Trackage rights over P&A.

Also would the P&A have to consider this trackage "double track" and follow Rule 251, or could it consider this a Main with Siding?  Would that effect how the tower (local control) controlled the two interlocking's at both ends of town?

Thanks

Ken L. 

Double track

So you DON"T have a single track mainline on the P&A, you have a 2 main track/double track mainline on the P&A.

I hope the P&A got a lot of money to pay them to give up the siding (because its gone).  The P&A has basically lost this location as a siding or meeting point.   I would configure it like this, much simpler to maintain and more flexible:

Lots of ways to do this.

Make it 2 interlockings with 251 in the middle.

Make it 2 interlockings with 261 in the middle.

Make it one interlocking.

Your choice. I would make it either all an interlocking or two interlockings with rule 261 in between.  The reason I say that is that the P&A will almost always keep all of their trains on the bottom track so they will need to go in both directions.  Actually the simplest way to do it is to just leave off the crossovers and make the P&A a straight shot in both directions , then just make the interlocking on just the bottom track.  If you make it 251 then P&A trains going right to left will all have to crossover on both ends.  If you make the bottom track bidirectional then they just go zipping thru at main track speed, in 251 a train going right to left on the bottom track would be limited to 49 mph (59 passenger) or going on the top track would only be doing 10-30 mph on the top track.  The only way to get a right to left P&A train across without delay is to make the bottom track bidirectional..

It is either 2 main tracks/double track or it is a main and a siding, but you can't have one track that is both a siding and a main track.  Pick one.  If its an Erie main track then you can't use it as a siding on the P&A, because you aren't going to win friends having the Erie main track blocked for an hour or two while you are making train meets on the P&A.  I had basically the same track arrangement at Pine Bluff where the city moved the SSW over onto the MP right of way and the single track MP operated on 2 main track SSW through town, but the MP controlled the dispatching of the joint section.  Of course that was two CTC lines and the dispatcher/control operator was either in N Little Rock 50 miles away or in Omaha, 1000 miles away.

So if I choose Rule 261...

...I would only need the two turnouts on the on the one line that is on the diagram above?

I need to also add an interchange track between the two railroads, and I will need to have it accessible from both directions.  This is why I think I will need to make it two separate interlocking's controlled by one tower (As explained above I still can use the Armstrong Levers to control the remote controls for the turnout switch points).

So how would that effect both what rules I used and the track arrangement for the turnouts for the mainline?

And just so I am understanding correctly, what rule I establish for the track must be the same for BOTH railroads?

Thanks again.

Ken L

Also looking to make track pattern more complicated..

OK, asking for your patience Dave because I know the prototype would want the track arrangement as SIMPLE as possible because every time you add a turnout or diamond it adds to cost of maintenance as well as making handling the traffic over the trackage more difficult.  I would like to add some complexity to the tracks for this town.  The track arrangement that I posted was so more signals and complexity for trains crossing both interlocking's would be needed.   Your track arrangement is definitely what the prototype railroads would want and do, so my question is, under what circumstances/needs/situation would a track arrangement similar to the one I posted  with the double track mainline and having the P&A use both lines, with the one line heading North and the other line heading south - would there be reasons why this would be done just for this town? 

BTW, in the "history" I created for this town, the P&A mainline was originally single track, so there was no loss of a siding.  At the time the Erie approached the P&A, the P&A was in the process of replacing an old wooden Howe Truss Bridge with a new bridge.  THe Erie said it would pay for whatever the additional cost was for the bridge to be double track.  

The other possibility that I never considered, but maybe I should, as having the Erie have to reduce to a single track to cross the bridge.  I am not familiar with any prototype having a double track mainline reduce to single track, it would defeat the whole purpose of having double track.  Sometimes sections of double track mainline is reduced to single track for maintenance but that is only for short periods of time.  Or can I do that? 

I don't mean to drive professional railroaders "nuts" by trying to add complexity.   I am adding complexity for the sake of complexity, but ONLY IF I can justify it.  That is create a back story and situation where there was no other choice but to do this.  Just to have it without plausible justification is something I do not want to do.  If there are no reasons, then I will do something else with this interchange.    This is actually one reason why I prefer to proto-freelance, and that is I can add things that otherwise would not exist in the area I would model.  Were I forced to model an actual prototype, it would be a toss up between the P&LE  (in OH and PA) or the NKP (between Conneaut and Bellevue). Both have many, but not all of the things I would like to have on a model RR layout.

Thank you for your indulgence in answering my questions.

BTW, laid another 15' of track, and about 60' of roadbed.  I am working on a town at a time, laying the track roughing int the basic scenery contours and installing the fasia.

So these questions are just not theoretical, as I approach each town I need to determine how the tracks will go.  I have the basic mainline determined, but each town is determined as I actually reach it.  One thing that is holding me up is making turnouts.  I need to make them because I want to use #12's on the mainline and the only way to have those in HO scale is to scratchbuild them.   I know those with more skill don't need the Fast Track Jigs, but for me, they are a neccessity! So I just want to ensure everyone who is answering questions this is not leading to analysis paralysis.  I am moving forward with construction!

Thanks all!

Ken L .

You Could...

... Have a single bridge with gantlet track. The not common this did occur and for a Model Railroad the disadvantages that the prototype would try to avoid with such a beast is actually an advantage as it slows down trains and makes the layout appear bigger.