The only way I have managed to stop a player from laying track is to remove their 'Build item' permission.
Steps to reproduce
- Start game in sandbox scenario
- Research all tech, choose to have starting items, but not cheat mode
- Enter permissions system at console, and remove 'Build rail' permission
- Try to build rail. It is allowed (not what I expected)
- Enter permissions system at console, and remove 'Build item' permission
- Try to build rail. It is NOT allowed (which I did expect)