# Crossover Colission Avoidance



## Jeff G (Dec 22, 2013)

I have a layout that has a 2 loop setup where two separately controlled trains cross each other. Thought it would not be an issue. Its only two trains, I should be able to pay attention and not run into each other. Wrong.... I have had issues when I have visitors talking to me or when I am looking at only one of the trains and BAM... they collide.
Is there a way to automatically shut off one train when the other train gets close? I am new to the forum.


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## Dave Sams (Nov 24, 2010)

Hello Jeff, and welcome aboard.

Yes, it is possible.

First off, your locos would have to be set to run forward all of the time.

Then you need either 153c contactors, probably 4, or sections with an insulated outer rail and some relays.


If anything I have said so far puzzles you, you may want to stick to the Gomez Adams method of running trains.


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## sjm9911 (Dec 20, 2012)

Jeff, there are lots of ways to do this, some simpler then others, what kind of trains, what kind of track, how big or small is the layout? Like Dave said A simple insulated track block would probably do. If the trains only run in one direction. I do like Daves uncle fester idea!


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## gunrunnerjohn (Nov 10, 2010)

I'm guessing since we're in O-gauge that they're O-gauge trains.


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## sjm9911 (Dec 20, 2012)

I ment it as conventional vs command question. I'm guessing conventional? But I've been wrong before! And now I guess Trainmaster control would add another controlling issue into the mix!


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## Big Ed (Jun 16, 2009)

Welcome to the site Jeff.

You should have had a video going.
You would be a star here. 

Gomez Addams was my hero with the way he ran his trains on the TV show The Addams Family.:thumbsup:


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## rkenney (Aug 10, 2013)

Here's a simple method with 153 controllers posted on the last page of the 153 instruction sheet. Sorry about the quality, I'd post it as a pdf but don't know if that's even possible.

As someone else mentioned both engine direction switchs have to be set as forward only.


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## Dave Sams (Nov 24, 2010)

rkenney said:


> Here's a simple method with 153 controllers posted on the last page of the 153 instruction sheet. Sorry about the quality, I'd post it as a pdf but don't know if that's even possible.
> 
> As someone else mentioned both engine direction switchs have to be set as forward only.


Nice looking instruction sheet. But, I don't see how it would work. If the trains were close to each other, the first one would pass the 153c and then would be stopped when it got to the insulated block. 

Adams Family!

I was thinking of an insulated rail before and after each side of the crossing. The insulated rail would cut the power to the oncomming train, and keep it cut until the last car cleared the crossing.


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## sjm9911 (Dec 20, 2012)

The first train stops before the crossover. When the second trainhits the sswitch, it powers the first train, then when the second train gets to the block it stops until the first train hits the switch.


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## Jeff G (Dec 22, 2013)

*Train type O scale 3 rail*

Hi thanks for the responses. The scale is O scale 3 rail. I would rather not have the train have to go in the same direction if possible. I am an electrician by trade and have installed light beam proximity sensors on conveyor belts at warehouse distribution centers that actually see across the belt and function accordingly. I was thinking that maybe crossing gates controls and such may have this type of setup. Haven't found any like that though. 
Whichever train proximity sensor sees the train first kills the center rail of the other train track till it clears the crossing.


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## sjm9911 (Dec 20, 2012)

Do you have a track layout for us to look at, all we have now is speculation. If the track is set up like above it will never work! There are light activated switches, and also command setups that can be pricy. Trains going in opposing directions is probably a disaster waiting to happen. It can be done in theory, but may not be the look your after.


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## rkenney (Aug 10, 2013)

What's been done on larger layouts sometimes is to place a resistor across the insulated rail sections (jumping it) to deliver just enough current to hold the E-unit from cycling but not enough to allow the train to move. When the first train hits the switch, the isolated track now gets full juice and the train resumes whatever direction it was in before.

Lionel suggested a 10 ohm 10 watt adjustable such as their rheostat. It would need to be adjusted to stop the train but not allow the E-unit to cycle.


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## Jeff G (Dec 22, 2013)

The train operation is conventional. I have recently got back into trains after taking 35 years off but plan to get into legacy and such in the near future.
I forgot completely about the effect that the loss of power would do with the reverser. That will be why a resistor would be needed so as to make the reverser not know that the majority of the power was lost which will stop the train but the resistor will keep the reverser in the same mode and thus when it is returned back to the original power level, through relays, it will resume running in the same direction.
As far as the layout goes it is approx 12'x 15' and is basically 2 large ovals that lay on top of one another so it crosses twice. One cross is 90 degrees and one is 45 degrees. One loop is a passenger train and the other loop is a freight train. There is a couple of small yards as well. There is no way to physically go from one loop to the other. I will post a diagram hopefully in my next post.


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## gunrunnerjohn (Nov 10, 2010)

Have you considered elevating the crossovers so there is no conflict?


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## sjm9911 (Dec 20, 2012)

You could also just switch the e unit to forward only.


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## gunrunnerjohn (Nov 10, 2010)

That doesn't solve the collision issue.


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## sjm9911 (Dec 20, 2012)

It going to need sidings! Unless it's two separate loop that just cross each other?!


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## rkenney (Aug 10, 2013)

Watch this guys video. He does exactly what you want to do. He uses relays, but the train detection is the same. One train stops while other train passes.


https://www.youtube.com/watch?v=uE5cpJas0zM


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## sjm9911 (Dec 20, 2012)

Bob, it says it's blocked I'm my country due to copyright laws?! 

I posted this awhile back when someone wanted to run opposing trains on one track. Not what your looking for but maybe something can get used. I still think a simple block will work.


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## Jeff G (Dec 22, 2013)

*Layout Pic*

I have posted a drawing of the layout showing the crosses. The loops actually cross 3 times but one of the loop crosses has 2 different elevations so there is no issues at that cross.
Done a bit of research and I am thinking of using 2 Dallee #553 optical detectors at each cross. The optical detectors would detect a train and cut the power to the opposite loop and thus preventing a crash. Obviously I would have to leave enough power on the loop I cut off so as to keep the reverser from activating and putting the other engine in neutral.
Has anyone used the Dallee #553 before?


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## rkenney (Aug 10, 2013)

You need to detect a train on either side of two crossings. That's at least 8 detectors. 

For the two detectors that are on either side of the crossing (same path) you need a logic that says no opposite train can proceed till both detectors are cleared (no signal) in succession. Intersecting track is dead on either side (you don't know which way the train is coming from.)

Logic must allow successive operation of detectors in either direction.

You must have isolation blocks adjacent to each of the crossing points (8) to stop the trains. Blocks on either side of a crossing (same direction) will share a power feed through a relay. (still need 8 'clip ons')

Isolation blocks will be operated with relays (4 -NC operated to open by crossing track logic.)

Or Gate should work. Output is 1 to turn off opposing track if either or both inputs are 1 (activated by detectors.) You need four OR gates. 74LS32 and associated support circuitry.


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## Jeff G (Dec 22, 2013)

The Dallee 553 will work with up to 3 infared detectors controlling the same relay output. I was planning on using one 553 with 3 infared detectors on each loop at each cross. (2#553 and 6 detectors at each cross) The 553 relay will be activated with the train coming from either direction and will remain activated till the last detector is cleared. The third detector would be installed near the middle of the detection zone for short trains. 
Since the 553 remains activated while any of the 3 are detecting would I still need to set up a logic system?


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## rkenney (Aug 10, 2013)

I'm not familiar with the 553 so I looked it up. 

It looks like you will need two boards for each crossing, one for each of the two directions. Despite allowing multiple detectors, the built in logic only allows operating one relay (one track block). 

Remember you need to turn on or off two different track sections (4 actually on each side of the crossing, but we can combine those two that are the same direction).

The sensors for these boards must be perfectly aligned at a 45 degree angle to the crossing. There will be no room for error and there is no self check to indicate proper alignment during operation.

All the planning in the world won't preclude the necessary trial and error. Many designs that look good on paper don't cut it in the real world. Have at it!


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## Jeff G (Dec 22, 2013)

Thanks for the input. I have attached a drawing of the detector locations. Could you explain your concerns about the alignment of the detectors?


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## rkenney (Aug 10, 2013)

With across the track detection sensors have to be aligned for correct operation (as opposed to reflective sensor where both sit side by side.) 

This sight has diagrams and products for what you want to do.

http://www.azatrax.com/track-crossing-protection.html


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