How To Create Tunnel Under The Base Level

SCARM does not allow negative track heights and it is not possible to set track level to go under the baseboard/workbench. However, you can lift all the tracks at some base height and then set the desired track section below this “ground zero” height – that’s the whole trick.

Look at the sample HO layout below – it is shaped as figure “8″ with two tracks station and main line, passing trough it.

To make the passing line to go under the train station, you will need to lift up all the tracks to let say 80mm (about 3,15″).

To set all track heights at some level, select all the tracks, select some height marker in the selection (no matter which), adjust its value and press Enter.
If you already have set heights and slopes for the tracks and objects in the layout, you can select everything (Ctrl+A) and then lift up the selection using the “Height shift” tool from the Toolbox (in menu “Tools”).

Then you will be able to lower the level of the passing line to zero and to place a tunnel under the train station.

It is also possible to make the two tracks of the station to pass over on a bridge.

Use this trick whenever you need to place some track section below the zero level of the baseboard/workbench. Remember to set the mode of the line (i.e. in tunnel) in order to be correctly displayed in 3D viewing mode. Download the sample layout from the links below and experiment with it.

See also
How to set heights and slopes
How to place tunnels and bridges

Sample layout

6 thoughts on “How To Create Tunnel Under The Base Level

  1. Hello,
    this works fine, in case You do it right on the beginning of the railway design.

    But what in case, I create several heights on a big layout and then I need a underground line? Then, all the work is lost because I have first set all tracks to a new base height and then I have to adjust all heights again from the beginning.

    That’s not a good idea.

    Or is there another solution?


  2. Hello Moritz,

    Yes, there is a solution ;)

    You need to select all of the tracks (use “Edit” > “Select All” menu command) and then mark one of the height values (no matter which). Press and hold Alt key and then adjust the selected height value – all other track heights will be changed simultaneously, preserving already set heights and slopes on the route.

  3. The problem I have is I’m building a large G gauge layout and I was hoping to use the heights (depths) to help with how much I have to dig or build up the ground level.
    Yes I know I can add or subtract the new base height,but I also need to take in to account the ground slope or elevation so the calculation can get a bit messy.

  4. Hi Milen.
    Not sure if this is the right place to post this but I can’t find an email address to write to.
    I have created a very complicated layout and somehow inadvertently created a higher terrain where there shouldn’t be one. The result is that roads I have placed, visible in 2D, now disappear into a green hill in 3D. No tunnel portal and the road (0 height) should just be on a flat terrain. Is there any way to correct this and flatten the raised terrain back to flat. I didn’t use polygons so I really don’t know how the terrain ended up being a long hill. I can send a screenshot of it if you supply me with an email address.
    Hope you can help.
    Thanks, Dave.

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