Oh boy, chiming in without seeing the show, but...
In Mt Lassen park, N. Calif, they get oodles of snow. When they plow the roads in the spring, they work by two methods. They had buried a cable in the road, from which they ran a signal down, and picked it up by a reciever if they were directly over it. The wire tended to break when the road expanded and contracted though.
Now, they are testing and proving the GPS methods. Some of the roads are cliffs; they can not see any part of the road to identify where they are at.
The key was the release of military strangle-hold on GPS. Before that, they were on the orders of meters. Now they are sub-meters.
Gosh I spell terrible!
RobertN in Shingle Springs Calif<P ID="edit"><FONT SIZE=-1>Edited by robertn on 10/28/00 10:58 PM.</FONT></P>