Rail viaduct under elevated RHW?

[RoddyUK 22]

Hey NAM people,

As always, many thanks to all the NAM devs team for your work, and for you and the community for answering simple questions that have probably already asked, but which I can't find ...

My current problem: I can't get a level one rail viaduct under a level 2 rhw, or a level 2 viaduct under a level 3 rhw?

Or the other way round (ie I can't get a level 2 rhw over a level 1 rail viaduct etc).

These are straigt criss-cross lines (ie “+“) so not complex.

PS if I can ask a basic supplementary question - is it correct that the section of a road bridge that goes over a road (again, just criss-cross pattern) is effectively the same as just a normal junction as regards congestion - and, if so, is it the same with a (flup) road underpass? Ie are they largely aesthetic?

(i thought I read that in a very old post which, given my ineptitude, I can't find, and may have misunderstood).

Many thanks to anyone who can answer either question.

Best regards, and thanks,

Roddy