It's been brought up a few times and even myself has tried to do this over the years but effectively no. However since you're still working on a small scale (9 boards rather than hundreds), you could try creating a blank area next to it and copy/paste with the selection flipped.
Add new blank boards around your current route to make the selection area rectangular and make sure the empty boards are equal or larger than your existing layout's length and width. Trainz may lock up for a few minutes after you click "paste", this is normal for copy/pasting big areas - just leave it until it's done.
I was going to say you most certainly can turn it around as I had the same problem, by 90 degrees. You simply copy 1 or all boards, having made up blank ones, and select the rotation tool before pasting onto the new boards.