I used to live in Los Angeles. The Westernmost cities of the United States tend to have a grid shape where the terrain permits. There are a lot of advantages to a grid shape, one being that it's much much harder to get lost. Another is that one blockage can always be routed around. The Internet was built on this idea, though in practice it has a lot of choke points.
Then I ended up moving east. The easternmost cities of the United States tend to have roads based on cattle trails, so everything bends and curves around for no apparent reason. And one immediate thing I notice: There are ways around clogs, but they're not always direct. In fact, they often make little to no sense. Except New York. New York is a grid.
Most communication, including transportation, benefits from redundancy. When there's more than one way to do something, no blockage is genuinely possible. You can always go around. This is helped by GPS devices that know where you are, and where the roads are, and how your road can lead to your destination. This is helped more by ones that have live traffic reports, quickly showing to you to the fastest possible route.
Another theory says that traffic grows to fit road capacity.