This quashes the notion expressed by a few people that public roads are somehow socialist. The topic of private railroads arises, but this also shows the large dissimilarity between public roads and railroads. Railroads in the U.S. are a closed limited-access system of less than 200,000 route miles. The public sector builds most roads and highways mainly because the problems of land assembly and assigning of costs to the various users have been so difficult that market solutions would be impractical. There are almost a million miles of private roads and thoroughfares on private property in the U.S., and 3.8 million miles of public roads.
Public roads serve multiple usages.
Most roads are used not just by automobiles, but also by trucks, busses, bicycles and pedestrians. Military vehicles and emergency vehicles use the roads too. Road transportation provides seamless travel to virtually every portion of land in the country. Often these underground utility lines are underneath the pavement itself. While some of these usages are minor, they are diverse and they all add up.