On November 8, Gizmodo ran a great piece by Rachel Swaby about the deterioration of the American road system, much of it based on interviews with Tim Lomax of the Texas Transportation Institute. The roads were originally designed for private cars, with the expectation that most freight shipping would continue to be done by train. They were mostly constructed out of compacted dirt with a layer of asphalt on top, unlike the German Autobahn which was asphalt on concrete.
Truck freight offered a particular advantage over rail for shippers: on trains, small loads of a container car or two had to be decoupled from the train and possibly coupled to another train for the next leg of the journey. The more times a train had to be stopped in a yard, "broken" and reassembled, the longer the trip for the entire cargo.
A full truck, by contrast, could hold a lot less than a full train, but it could go directly from the loading point to the unloading point. Both freight railroads and road builders were surprised by the speed of the shift from rail to road. The roads were paid for by the government, and most of them were "free." Lomax tells Swaby that "companies are pushing the limits of what our roads can take, which increases their profits—but at the taxpayer's expense." It's clear to me that this has been going on for as long as there have been companies.
You probably know what happened next. The railroads began losing money, and cut their passenger service first. American housing and retail reorganized themselves around roads, and manufacturing and other industries followed. Faced with such intense demand for the roads, the federal, state and local governments embarked on a massive expansion plan. This just fed the appetite for more roads.
I've known for years about this vicious cycle of road subsidies, but I didn't make the connection with the use of dirt instead of concrete under the asphalt. It makes me wonder: if all these roads had been made with concrete, how much longer would it have taken to build out the 1950s era Interstate system? How many railroads would have avoided bankruptcy? How many downtowns would have been saved from being paved over for parking?