as a theoretical problem highway should be much easier because few types of "street agents" can access them (i.e. no bicycles, no pedestrians, no traffic lights)
As far as I know, they already have a pretty good handle on limited access roads.
People use 'highway' to describe all manner of roads, I wonder if the gp is thinking about major 2 lane roads that have higher speeds but still lots of intersections to deal with.
