AVEVA Review can import RVM, DGN, ZGL and a few other formats. No it's not free. There is also AVEVA NET as well, which can accept any format. It's not free either.
Autodesk Navisworks Simulate (not free) could open .rvm from pdms and save it to .nwd. this .nwd youcan oipen in Navisworks Freedom (it is free).
This is the cheapest way.
