Calculate the distance from a user defined point to the nearest railway-line in 3D

Hello community!

I’m new to the VetriGIS Studio platform and may need some guidance.

What I’m trying to make, is a workflow that calculate the distance from a user defined point to the nearest railway-line in 3D. The 3D-part is because the railway-line may be in a tunnel belove.

I’ve managed to do it in 2D (as shown in the picture), but the 3D-part is a bit more challenging.

To calculate the distance in 3D, I need to add a Z-value to the user defined point.
Here in Norway, the Norwegian Mapping Authority has an API where you can send in a X/Y-coordinate and get back the Z for that point. 
I’ve done this with a web request, then parsed the JSON and extracted the Z-value to a new value. Then used Get Geometry From JSON to recreate the point with the Z-value.

Then I query my railway-layer to get all railway lines that is within 50 meters of the user defined point.

Then comes the part I’m struggling with.

How do I find the nearest part on the railway line and get the height from that point? (The height of the line, not the height on the surface).