http://img693.imageshack.us/gal.php?g=csptrain0000.jpgWhat layouts are you using for the official CSPromod Maps?
CSPromod's official maps feature near-identical layout recreations of their original CS 1.6 counterparts, with enhanced graphics that do not affect gameplay or FPS in a negative way.
Make the train supports (the thing the wheels are attached to) like in 1.6, just box-like. Before you start with the fan boy thing, look at the screens. You can clearly see underneath any train now, with the CSS viewheight, imagine with the lower 1.6 viewheight how it will be...
Another problem would be the wheels they provide some pixel shots which with the awp could be very damaging, (like in CSS you don't even see where they killed you, a hide and seek game).
If you are a beta tester you can easily recreate to see what I'm talking about. Get an awp and go outside and look at ladder train... or from generator to outside bombsite those are just some examples. Keep in mind how it would look if you had 1.6 viewheight!
I'm writing this because I don't see this as a graphical bug. It's realistic only the wheels touch the ground and I don't think you intend to change it but please first think do you really think gameplay will be the same with everyone looking being able to under every train like this?