The original plan was to only have 7 roads - - - - three east - west and four north south. The Isystem is required to have one out of every five miles to be straight so that in a time of war we may have airports taken out but we would be able to use the Isystem as runways.
They did the same thing in Switzerland and originally used rubber poles as dividers of the opposite lanes so they could be pulled up and the road used as runways for aircraft.
. . . . and in the beginning the novelty of the Isystem was such that familys in Penn would drive out and park in the 12-20 foot medians on Sunday afternoon and have a picnic lunch . . . . checkered table cloth on the ground and everything.