There are some displacement maps that are the same thing. These are found in the topology tool - the topmost tool used to raise and lower land and add water.
Click on the advanced pulldown.
With "Ground" and "none" displayed, click on the arrow to the right of "none".
You'll see various greyscale images. To use them, choose one of the images.
Draw a square using the area selection button on the lower left.
Using the horizontal slider, you can adjust the height to increase or decrease the contrast, thus the height of your map.
Once satisfied, click on the fill area button - looks like a beaker with red liquid being poured into it.
The bigger the area you select - you can do this by zooming out carefully and selecting a whole baseboard, the more you can fill at once and create a whole landscape this way.
I can't remember if there are any displacement maps on the DLS, but if they are, download some and then clone them and import your own images.
Here's a website you can use to download grayscale height maps. It says to generate maps for Cities Skylines, but they work the same in Trainz.
terrain.party