1990 Problem B:  Two Snow Plow Problem

The solid lines on the map represent paved, two-lane roads in a show-removal district in Wicomico County.  The broken lines are state highways.  After a snowfall, two plow-trucks are dispatched from a garage that is about 4 miles west of each of two points (*) marked on the map.  Find an efficient way to use two trucks to sweep snow fro the county roads.  The trucks may use the state highways to access the country roads.

Assume that the trucks neither break down nor get stuck and that the road intersections require no special plowing techniques.