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How To Stop Tunnel Derailments

Michael S asks readers:

“I thought I was doing the right thing by using flex track in my tunnel, but I am experiencing derailments. I do have a rail join in the tunnel curve and I suspect that could be the issue. Your help please.”

13 Responses to How To Stop Tunnel Derailments

  • David Marquissays:

    Any time I use flex track regardless of gauge, I offset the rail joints by 5 sleepers (ties) this puts the jointer opposite a solid rail keeps the rail in gauge in turns of most radius. Also make sure the jointer tabs match the flex track code of 100, 83, 70, and so on, if you are using code 83 rail and your joint tabs are code 100, the wheel flanges will hit causing derailments.

  • john lebsanftsays:

    depending on the length of your tunnel, if short, try to have one full length of track inside, if not, solder the joint straight and go from there. hopefully you will have ample access to the tunnel to retrive derailed rollingstock.

  • David Stokessays:

    You could do what the real railways do and install check rails in the area of the joint. Check rails are similar to wing rails in a turnout, but longer. they “encourage” the train to stay on the track. Also, make sure that the “ties” or sleepers are all perpendicular to the rails and not skewed, making the gauge tight.

  • Phillip Collinssays:

    If I must have a join in a (sharpish) curve, I join the tracks and solder them together first; then I curve them outwards from the join towards the ends. My radius is about 40mm (N scale).

  • Phillip Collinssays:

    Sorry, that should read 400 (four hundred mm). Damn keyboard!

    • Phillip Collinssays:

      Correction 400mm!

  • Newman Atkinsonsays:

    Hi Michael, All good suggestions for tracks in tunnels but here is the solution. One of the guys said something to the effect to make sure your flex track covers the length of the tunnel. One piece is not always enough like mine. So lay out your flex track as you need it. Cut and fit for the whole curve ( assuming you have a curve in the tunnel) Do one joint at a time and after the track is fitted allow the rails to straighten. Connect the joint with a joiner and lightly solder the outside of the rail with the joiner. Relay the complete section and the joint will act as one continuous rail. Don;t get the joint to hot and melt the ties That will also pull the rails closer together. If multiple joints are required do the same on them. Set the first section in place and add the new section and fit. Allow that connection the straighten and do the same with that one. You are essentially making continuous welded rails as they now do on the prototype track. If you have a connection in that tunnel such as at a hidden switch, If the connection to it cannot be made with the joint smooth and straight plan in a short sectional track piece that you can solder the joint to just before the switch and use the short sectional piece to connect to the switch. That saves soldering to the switch itself and ensures the flex track has a way to hold the alignment. I have been very successful in installation of flex track this way. One other thing I have pretty well gone to no nail installation as if you use track nails many of us don’t know our own strength when hitting the nail with a hammer and we end up pulling the tie down to far. Depending on the surface you are mounting to, end up having dips in your rail. By using APEX Caulk you do not pull your roadbed or your tracks down and you have a more level installation. If you make a mistake and or the plan didn’t work out like you thought them use a thin bladed putty knife / spatula and slide under your rail ties and it will come right up and if you need to move the roadbed it will do the same as well. Using shop glue has a tendancy to make youe track not flex as well for changes and same with the road bed. even switches I use this but I only use it in 2 or 3 places away from moving rails It will hold fine. You might also install a wire drop as you solder your joints that way you have good connections to go down and connect to your rail wire buss below the table. APEX caulk is very cheap and comes in a construction tube get the clear and it will apply white and dry clear. 15 minutes or so the rails will set in place on their own. Works great on setting the road bed. Just draw your center line and it holds well in place with a small length of board on top with a little weight. Same thing it will set in about 15 to 20 minute enough to continue on down the line. Hope this helps. it works very well for me. It also holds better on styrofoam where nails pull out. from Newman Atkinson

    • Newman Atkinsonsays:

      Thought I would add to my comment here. Due to a furnace replacement I had to pull 2 sections of layout out for the technicians to install the new one When I went back in I found they had installed the filter box right at the table level and the layout would have to be broke down just to change the filter. Not a good plan
      The section is being reinstalled and this time on hinges. But the tracks must be shifted to leave room for the hinges. Well this was my first 2 sections I had built. The road bed was nailed and so was the track (most of it was flex track). As I reset the track the APEX caulk system of mine will be the new mounting system for it using the APEX Caulk. As I pulled up some of the old cork several places have already broke getting it up. With my new caulking installations it is easy to pull it up with no or little damage.
      Now since I am hinging the section I need to have rail ends that match each other so when it is in place the rails will align with little or no gap. There is no clunk – clunk as your wheel trucks cross the joint The short sections near the cuts will be laid by soldering the rails to PC Ties made of computer board. When they are done they will be mounted just as I have said above. when the section is down in the running position the rail ends will meet very close by using 45 degree cuts so even if the rails don’t meet exactly there will be almost no gap for your wheels to cross. No more clunk-clunk. As I make repairs or changes I mount using the caulk now. It does make a difference. When I get this section done I will have a video of it and how it was done to see sometime in January. Newman Atkinson

  • Tim Morloksays:

    All the above replies are great. I am planning on using flex bridge tracks in my long tunnels since they have the check rails for their whole length. Another option, if you have straight track in the tunnel, is to insert a rerailer inside it. Tim

    • Newman Atkinsonsays:

      Tim, A rerailer is always nice but I usually don’t put them in anymore as if you have well laid track you should not need it. I do how ever put one in about six inches out from a pass through gate or something critical like that. There I put them on each side of the gate so if a wheel is off it will catch it before it gets to the gate section and hopefully put the whhel on the track before it crosses the gate. I also use a different kind of cut on my rails when matching the rail up where the gate opens and closes. Friends have had drop in sections across doorways and such but the cut the rail so to clear the edge as you install it. I on the otherhand cut 45 degree angles through the rail and as the gate section closes of if you are doing a drop in then the rail will join up evenly and there is no gap on your rails. If done right there is no gap in the rails, The 45 degree angle lets the rail cross over ao the permanent section and since it makes up a complete rail there are no gaps. There are no clunk chunk at your wheels cross the gap.

  • David Broadsays:

    The best solution in 00 or H0 is don’t use flexi in tunnels. It always tries to straighten out in use.
    I made this mistake and have spent 20 years trying to stop the rail joints kinking.

    The answer is to use set track in tunnels, and for any sharp curves, I use the nearest radius I can slightly smaller than the radius I require and cut the webs between sleepers just like would with flexi and ease the set track OUT to the radius I require, that way it won’t try to straighten out even if not pinned or glued down too firmly. I wouldn’t offset the rail joiners as this can cause the track to go out of gauge but its absolutely essential that the outer rail rail gaps are the same or smaller than the inner, file them up to get it right. If you lay in winter allow for expansion and ideally use droppers and a bus bar for each hidden track section, that way rail joiner problems don’t become an issue. Flexi is good for straight tunnels but build it on a sub base so you can pull it out in case of problems. My 3 metre long tunnel goes under my rockery in a drain pipe and I pull the track base out for maintenance

    • Newman Atkinsonsays:

      David Try what I have been doing and have told Michael about above. It gives the whole tunnel like it is one welded rail like the protos have. It has been a life saver for my tunnels. But you need to straighten the track before soldiering the joint. So fit and cut the rails as needed then straighten the pieces and soldier the rail joint, Good time to add the wire drop while you are doing that if needed. reset the track and what a big difference it will make. I also do not nail my track down as with my heavy hand on even a tiny hammer It is easy for me to pull the rails down too far and have ups and downs in the rail. I now use APEX clear caulk to install both the roadbed and the track. it will set in 15 to 30 minutes so you can keep working down the line and will set good by the next morning. Get the clear It goes on white and dries clear. I just smear it on with my finger on the top of the roadbed and then just set the track on it in position (and you have plenty of time to make adjustments). I usually do lay some good flat boards on top of the rails and set a weight on top of that. That spreads the weight evenly over the rails. If you need to change the position of the track or completely redesigning, Just run a thin Putty knife under the ties using several passes and you are off there and ready to make changes and you are able to reuse the track. Same goes for the road bed. I am doing that to some rails I am making changes this afternoon. My only problem is I nailed and used shop glue to install the previous work. From my first section I layed on my layout to the present day work I have made several changes as how I do it now. Soldier joints make flex track continue on around a curve as if it was one full rail. It will fix most any thing in your tunnels. I even do it on long open curves so there are no kinks. Save the not soldiered joints for the straight away’s where it is not a problem . Even a flex track attached to a sectional track or a switch ( if that flex track is coming out of the curve it will bow the joint.) On a switch connection of that type I will use a short sectional track piece and soldier the flex track joint to that to hold the joint in place and then connect to the switch Soldiering onto a switch is never good. Newman Atkinson

  • Richard Waltersays:

    It’s always a good idea to splice in rerailers in difficult to reach spots regardless of the accuracy of the track.

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