Straight double track

I have created a double track form my routes, but when I try to apply "straight" option the track is not affected by this.






Is it only possible to apply this option to single tracks?

It only applies to single pieces of track and not double tracks. Its been that way since tge very first Trainz game so not a bug.

Cheers

The reason is that double-track is considered a type of bridges or tunnel and neither of these assets can be straightened. As said, it's been this way since the very beginning.

Double track also has other "issues" such as attaching switches and other objects. For that plus the reason given above, I never use it. Easier, and almost as quick, to lay two single tracks side-by-side at a spacing that suits you plus you control the default direction (for placement of signals, etc) of each track.

My thoughts.

Thank you by your answers!
Cheers!

On my prototype route I realised that there are several sections that are straights seperated by curves. To construct these, I use waygauges. Search the DLS for "waygauge", there are several.
Place a waygauge at each end of your straight sections.
Join with normal spline single track. There will unavoidably be an S-curve.
Rotate the waygauge objects to reduce the curve as much as possible.
Delete the waygauge objects.
Add more track for the curve sections. Add it directly to the existing pieces, don't add it close then move into place as that will affect the position of the already laid end spline point circles.
Apply "Straighten" to your straight track sections.
That's it, you now have a series of straights and flowing curves, all correctly spaced throughout!

Thank you for this interesting trick!