Eisenhower's intention was to build a National Defense Highway system to link military bases, defense plants, and shipping ports (sea and air) with roads that would handle the largest and heaviest military loads. His original idea was modeled on Hitler's Autobahn network, and like the Autobahns, the Defense Highways were not to go into the cities except by a minimal number of spurs, or stop at an outer ring. This model is still widely used in Europe, where they've learned from our experience that superhighways into and through cities change the nature of cities in undesirable ways.
The project got turned over to Congress and became something larger, bringing in the states, cities, and the trucking and highway construction industries. What came out of it was using defense money to build urban expressways and link the cities, and provide the construction industry with a lifetime task of building and rebuilding disposable roads.
At least before the whole thing got too far, it came off of the Defense budget and onto a newly created Highway Trust Fund with dedicated income sources.