North Eastern Railroad

[jvaughan]

I found this great explanation about reversing points on another website. It is by Rich Garber and it does a great job of explaining how they work and their impact when using them in an activity.

Reversing points were made and then unexplained by Kuju to make activity developers lives miserable I think. The reversing point is typically why people have trouble finishing a activity. So let me explain these buggers in some detail. So put out the 'gone fishin' sign and let's begin.

A reversing point shows up in your track monitor (F4 key) as a squiggley arrow. As you get closer to the reversing point, the squiggley arrow moves toward you. Makes sense right? Well, the problem is, down at the bottom of the track monitor is what you mistake to be your engine, the teal colored arrow pointing upwards. Alot of people mistakenly think that when the arrow head crosses over the squiggley mark, they have crossed over the reversing point. After that build up I'm sure you can guess what I am going to say next.

WRONG!

You haven't crossed over that reversing point until that squiggley arrow disappears off the track monitor.

Okay you ask, so what's the big deal? The big deal is all the trains running in the sim are governed by a path laid out by the developer. When you cross over a reversing point, you literally wake up the next leg of your path. So, if you don't cross over the reversing point properly, the next batch of signals won't give you a green. Sometimes you can permission past them but not if an AI train is approaching you. And you do have an AI train approaching so you won't be cleared.

Now there's another problem with reversing points. Generally, I lay paths in my activities that get you to a location, but I don't draw out the exact path. So for awhile, you're off on your own. I like doing this. But on your end, you can't tell when you're off the path or not, so its confusing for you. So you're next hurdle is to think like I do. Scary thought, I know. But that's one of the big problems with the whole activity scene, is you have to learn how the author does things to complete the activities. So expect some trial and error as you get used to my idiosyncracies.

Reversing points have another unique feature to them. And this is very important. When the activity developer lays down the reversing point, he has a fundamental problem. A reversing point is activated when the whole train fits between the nearest switch AND the reversing point. Normally I would have said it this way, a reversing point is activated when the whole train fits between the switch you want to reverse through and the reversing point. Lately, I believe its the former rather than the latter.

This is tricky stuff here because the AE doesn't allow for 'just' crossing over the reversing point, but rather, the whole train has to fit between the two. So why is this so much trouble? Because there's no reference to the size of the train if it is something built up over a series of pickups or drop-offs! In other words, the activity developer has to guess the length of the train. (A critical reversing junction may not take place in an activity for a long time. I had one activity I created where the reversing point to be tested was 45 minutes into the activity.) This is also one reason why changing a consist for an activity can mess up an activity. If the length between the reversing point and the nearest switch isn't big enough to accomodate the new size of the train, your train will never be seen as achieving the 'fitting' criteria. In some instances I leave extra space for just such an occaision. Other times, there's just not enough room between the reversing point and the nearest switch to accomodate the whole train. Because of this, it is essential for a route designers to give plenty of track between critical switches.

I would imagine Kuju had in mind that they need the whole train to pass through to make sure a switch isn't thrown with some parts of the train still not having gone through the switch. This is the only reason I can think of they have it this way.

There's one more facet to reversing point that's extremely important. I'll cover that next time in this continuing series of How Activity Creation Drove Me Mad.

This last post on reversing points is pretty important to developers, and to users as to why sometimes complex activities don't work properly especially given timing.

The best I can figure on the last implication of reversing points involves what a reversing point does to signals. When a player train crosses over a reversing point and the next leg of a path is activated, a problem seems to occur with AI trains and signals. In my Activity Tutorial I discuss what I learned in the early days, The Three Signal Rule. This rule basically states that if an AI train is introduced into the player's own set of three signals ahead of the player, MSTS's AI isn't able to react properly and the signals foul allowing either a collision or a stalemate to occur.

Again, with nothing able to be set in concrete, this means, if an AI train is within three signals of the player train when the reversing path is crossed over, since the player train's next leg of the path is just being activated, you have the potential for violation of the Three Signal Rule.

Let me say that another way. The AI seems to lose all focus on what has happened between the player and AI trains to that point. So developers, keep your AI trains a extra window of time away from the player train when it comes to reversing points, especially, if the player train's path crosses an AI Train's path.

So how does this effect the user? This means that the player once again has to have the same mindset of the activity developer when playing the activity. In other words, the activity developer becomes the prototype by which the activity user has to become accustomed to. I agree that this is not an ideal situation. So when you find yourself in a yard or en route and are behind schedule (even if it's one you as the user are unaware of), you could be severely altering the outcome of your activity episode. Hence, this is why you hear as users, 'timing is critical.'

Rich Garber

[PJ]

Very interesting Jim.
If I understand what Rich has said here correctly I think I must correct or clarify one issu here.
Rich wrote:

[jvaughan]

Honestly, I'm not real clear on what you are trying to say here.

My experience, from my own use of the reversing point, is what Rich is saying is true.

Do I believe there might be exceptions? Yes. Have I found any? No.

Can I think of any that might exist? Yes.

Is what you are trying to describe a possible exception? Yes.

The big key here is for folks to understand that when they are running an activity, that they must cross a reversing point properly in order for it to activate properly. I have seen many messages from folks saying they crossed a reversing point and it did not activate. Upon asking it was apparent that they had not actually crossed the reversing point (when it disappeared from the track monitor) but had merely crossed it with the direction arrow on the track monitor.

[artimrj]

1. The train must not be touching a switch, front or back, while crossing the reverse point. "So it has to fit in between."

2. The reverse arrow must dissappear or you didnt cross it.

3. If the reverse arrow never dissappears, you were touching a switch while crossing the reverse point.

[PJ]

Jim. What I was trying to explain was an exeption. It was not my intention to suggest that people should try this out if they are not 100% sure of what the outcome of it would be. I simply wanted to inform people that are a few trix that can be done with the AE. And the placement of the turnaround point when reversing is one of them. I'm sorry if I have confused anyone by mentioning this.

The best way of doing it if you want to 100% sure of what the outcome will be is to do as Bob said:

[jvaughan]

And what Bob is saying is exactly what Rich is saying in the above.

As far as your comment about an exception, I just can't picture what you are doing in your activity.

[artimrj]

I just said it in less words.

I think I understand what PJ is saying as I have run into it also.

Rich also mentions not being able to tell the length of the assembled train.

I make a consist that would be the assembled train, place it on the tracks where the reverse point is going to be. Center up the screen so you can see, then when you open the path editor, before you click to actually open it, move the window so the corner of it is where your train starts, BECAUSE when you open the path editor the train dissappears, but the corner of the window will give you the general location. Put your reverse point there and you shouldnt have to test it too much, except maybe to move the reverse point closer to the switch. I try to make it as close as possible to emulate real life. The conductor dont want to walk back 1/2 mile to throw the switch.

This thread should be moved to the Activity Editor forum.

[Darkfyre]

I was making an activity for FBL2, going from Fort Fairfax, around Lake Hurst Yard, and reversing back to Fort Fairfax (yep, half of the activity is in reverse )

The reversed path soon overlapped the original path, on single track.

I attempted to switch off, to keep the train in the righthand 'lane'; and the green line that showed the path disappeared completely.

Could anybody tell me what went wrong?

[elementb]

I am not sure what you mean by "switch off", when you create reverse points MSTS will keep track of the path even if it goes over its self many times which is good for MSTS but the only problem is that it is almost impossible to edit once you have completed it so when you are laying down paths you should usually try to do it in one shot if possible.

[robertr]

To add to the confusion, the activity developer should indicate whether it is an entire train going into the siding for a reverse point, or whether it is just engines. I have watched a lot of local switching being done around here in a very small place (UP, btw) and they rarely back into a siding to pickup with any cars still behind the engine unless they need a 'handle' for one reason or another. Standard procedure seems to be to leave the cars on the primary siding, then go in, pickup and bring out. Or if they are leaving cars, they usually only take in the ones they are dropping.

I don't know if this is prototypical up and down the line, but it's what happens here about 90% of the time.

[flash]

Your are right about the handle. If an industrial siding track is questionable, then they use flatcars or whatever is available as a reacher so that an expensive and heavy engine does not go on the ground.

[Darkfyre]

By 'switching off' I mean right-clicking and selecting 'take other exit'

[kevarc]

Bob, I am not sure exactly what you mean by not touching a switch? I have done paths the the player consist is draped over a ladder track with the attendant switches and not had problems. I have also done them where I have the train approaching the reverse point and had a crossover to the other track underneath the train. Again with out problems. The Rockport area is another where if you are pulling cuts of cars from the sidings north of the wye your train will be draped over about 5 or 6 switches.

[artimrj]

"Touching a Switch", this is hard to explain. First it is only the first and last cars that are effected in this. There can be ladder switches under the middle of the consist. By touching I mean, in the block of the switch, far enough in that it won't throw and your touching it.

Also it has been a while since I did a work order with this scenerio, but it may be the switch you want to throw is the one you can not be touching. Say to back into a siding. You have to be completely passed your switch before hitting the reverse point or it wont dissappear.

[robertr]

Would this be the same as completely 'clearing the switch' that will be changed? Probably just semantics? Also, I've found out many times the signal (if there is one there) can severly affect the speed limit that is imposed, depending on whether there are cars or no cars on the track you reversing onto. Can't wait to see what MSTS2 has to offer