Vehicles move in a much higher speed than usual when they're in express ways. Express ways are meant to provide a faster option for vehicles which have a very distant place as a destiny that would most likely take a ridiculous amount of time if combined with traffic and traffic signals. Since cars move really fast inside an expressway, getting in one at the middle of it might be quite dangerous already. Therefore, the access points must be carefully controlled for safety issues, hence the name: "controlled-access roadways".