
In the 1950s the LeTourneau company developed several overland trains, essentially oversized semi-trailer trucks that could travel over almost any terrain. Their intention was to be able to handle logistics needs without being dependent on local road or rail systems, allowing them to operate in back-country areas.
Read about it here:
http://blog.hemmings.com/index.php/2009/11/19/54-wheel-drive-the-letourneau-electric-arctic-land-trains-that-put-australian-road-trains-to-shame/ because Dan at Hemmings wrote a cool long post about the land trains
For other crazy polar exploring vehicles:
http://justacarguy.blogspot.com/2009/12/arctic-or-antarctic-explorers.html