Invalid Railroad Regression Error
I would put this in Beta Bugs but I know that technically it is not a bug. So I am going to make it a suggestion instead.
If you have a railroad segment cross a street segment and you decide to junction them.
You get an error when you save telling you that all turns are disallowed.
While technically this is true, you CAN"T allow the turns onto/off the railroad segment (and you shouldn't be allowed to).
This is a left over error from back when turns could be set on railroad segments and needs to be removed. It causes extra unneeded steps when adding the junction.
This seems to be a bug.
A bug was opened to the relevant teams in the HQ.