The majority of G&W lines are small enough to be Class III,
although a few are big enough to be Class II:http://en.wikipedia.org/wiki/Buffalo_an ... h_Railroad
None are Class I.
Although as a whole, you cant really say the G&W is Class-anything..since its not one railroad..
you have to take each "G&W family" shortline on a case by case basis.
There was originally the ancestral Genesee & Wyoming Railroad of NY state..a Class III shortline.
A salt-hauling railroad that existed from 1894 to 2002:http://1stclass.mylargescale.com/Scottychaos/GW/
That original G&W was absorbed into the Rochester & Southern Railroad (the first of the "G&W family" shortlines, after the original G&W) around 2002, ceasing to exist as the original "Genesee & Wyoming Railroad"..
then, for reasons I still don't understand, the G&W Corporation "gave" the "Genesee & Wyoming Railroad" name to one of their shortlines in Australia!
which makes no sense to me at all, but there it is..
So today, all of the "G&W family" shortlines have their own name (Rochester & Southern, Buffalo & Pittsburg, Huron Central, etc)
and one of those "family" railroads happens to now be the *Second* Genesee & Wyoming Railroad, in Australia..