I am aware that simutrans pak 128.britain has a built-in motorway sign, for one way highways, but I would like to have the elevated highways. Where can I get them? (As a compatible addon)
I have always liked the Japanese ones:
http://japanese.simutrans.com/index.php?Addon128%2FRoadTools%201
The page is in japanese, but if you scroll down, the files are easy to find.
Fabio released a release candidate for new roads for pak128 - it is not finished, but it works and has elevated highways:
http://forum.simutrans.com/index.php?topic=3233.msg67815#msg67815
In both cases, note that they should work in pak128.britains, but could look a little out of place due to the different drawing style between the paks.
No biggie, my browser translated most of the page for me.
You could always offer to draw them for pak128.Britain - I don't have time to do much and people tend to draw what they want to see in the game...
How about this? (http://simutrans%20pak%20128.britain%20highway%20idea.bmp)