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Using an Arduino to Protect a Train

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  • Member since
    July 2008
  • From: Holt, MI
  • 181 posts
Using an Arduino to Protect a Train
Posted by JPD on Friday, April 2, 2021 2:04 PM
Some time ago I saw a video where the person had devised a way to stop trains rolling off the layout when a lift out bridge was removed using an Arduino. The device was triggered by the removal of the lift out bridge. The Arduino would then raise two small piano wires to block the tracks on both sides of the gap. I have hunted for this video without success.
Do any of you know who did this interesting solution to the problem of stopping trains from taking a deep dive? I would like to give this approach a try, but I know nothing about Arduinos.
  • Member since
    December 2001
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Posted by mvlandsw on Friday, April 2, 2021 10:57 PM

It doesn't seem like an Arduino is necessary. A simple contact that actuates a Tortoise switch machine to raise and lower the pins would work. If you want to keep the contact as simple as possible it could control a DPDT relay to reverse the switch machines.

Mark Vinski

  • Member since
    December 2016
  • 98 posts
Posted by speedybee on Friday, April 2, 2021 11:51 PM

Arduinos are great! But in the application you describe, it sounds like the train would just crash into piano wires and keep on driving until the engine derails... better than a tumble to the floor, probably, but still going to do damage.

IMO if you're using an Arduino for this job you should have sensors under the track about a foot away from the gap. If a train approaches the gap when the bridge is removed, the Arduino cuts power to the track. And maybe lowers a barrier too, for good measure.

If you have keep-alives though, your Arduino would need to send a DCC emergency stop command before cutting power; also doable, just a little bit more work.

If you're interested in jobs like this I encourage you to get into the Arduino! But you'd have to start with something a lot simpler, like LED signals or whatever, to get your feet wet. This project is beyond the scope of a complete beginner.

  • Member since
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  • From: somerset, nj
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Posted by gregc on Saturday, April 3, 2021 6:29 AM

if the goal is to prevent accidents, you could drill a hole and drop a nail into it to block cars.

greg - Philadelphia & Reading / Reading

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    January 2009
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Posted by RR_Mel on Saturday, April 3, 2021 10:08 AM

Mine was a swing up section across a doorway in the middle of a 10 foot block.   I simply used a door bell button to remove one rail of the track power to the block with the bridge up.  With the bridge down and in place a bracket on the bridge pushed in the door bell button to restore power to the block.

That worked great from 1951 to 1958, I never had a problem and it was totally automatic operation.


My Model Railroad
Bakersfield, California
I'm beginning to realize that aging is not for wimps.

  • Member since
    September 2002
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Posted by ndbprr on Monday, April 5, 2021 6:19 AM

Being totaly sarcastic because the electronics are taking over everything why not an IBM mainframe computer?  That way big brother can monitor what trains you run and either collect more data on you or shut you down completely.  A microswitch that the bridge activates when in place can shut the power off to a big enough section that everything comes to a halt way before the big chasm.

  • Member since
    July 2006
  • From: St. Louis, Missouri, USA
  • 572 posts
Posted by alfadawg01 on Thursday, April 8, 2021 4:49 PM
And if you want to use an Arduino, drill a hole through it's circuit board and run the nail through it into the track. That'll stop anything.


"Never try to teach a pig to sing.  It wastes your time and annoys the pig"

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