This logic—that higher design speeds make for safer streets—coupled with the typical city engineer’s desire for unimpeded traffic—has caused many American cities to rebuild their streets with lanes that are twelve, thirteen, and sometimes even fourteen feet wide. Now cars are only six feet wide—a Ford Excursion is 6'6"—and most Main Streets were historically made of ten-foot lanes. That dimension persists on many of the best, such as ritzy Worth Avenue in Palm Beach, Florida. Yet many cities I visit have their fair share of twelve-footers, and that is where much of the speeding occurs.
