Sitting in a stopped car at an intersection, waiting for the light to turn green and traffic to clear out of the way so you can get where you're going is no one's idea of fun. But we soon may be able to say goodbye to all that--a lot sooner than you might think.
That's the word from the geniuses at MIT, who have figured out a way to eliminate the stoplight--that annoyance of modern life--and replace it with something called "slot-based intersections." In a slot-based universe, they explain, cars approaching an intersection would slow down to allow each other to pass, but they would never have to come to a complete stop. 
Instead, they would be sorted into groups, much the way airplane passengers are invited to board a plane based on their row number. The system would automatically group, say, all the cars turning left from Street A onto Street B and send them all through the intersection at the same time, while slowing down the cars going straight through the intersection until they've all made the turn. Then it would slow down turning cars, and send those going straight into the intersection. And so on.
How would this slowing down take place? One obvious solution is self-driving cars, which could receive data directly from a traffic control system and proceed through the intersection safely. But although the technology for self-driving cars has existed for a while, a legal framework for them, as well as widespread societal acceptance, are still a ways off. It will be a very long time before we can be confident that all the cars approaching any given intersection will be operating under their own guidance.
Fortunately, say MIT researchers, we don't have to wait until then. On-board computers and cruise-control technology already present in most cars on the road today could ping the traffic system as you approach an intersection with information about whether you plan to go straight, turn right, or turn left. (You'll have supplied that information by using your turn signal. You do remember to always use your turn signal--right?) The system would then relay information back to your on-board computer and impose a maximum speed through the intersection, placing you in the correct group of cars and allowing other groups to pass through safely. 
In terms of the necessary technology, "You won't need to wait 20 years," Paolo Santi, one of the study's authors, told Fast Company. "We don't need autonomous driving. It's actually much simpler."
Maybe so. But there's an even simpler way to speed up traffic through intersections that doesn't require on-board computers, self-driving cars, cruise control, or even traffic lights. In fact, this method is in use throughout Europe and has been for decades: the roundabout. Like slot-based intersections, roundabouts allow many more cars to enter an intersection at the same time than traditional stoplights do, often without having to come to a stop. Many Americans who've spent time driving in Europe (such as my husband) came home fervent converts to the roundabout approach, convinced that they speed traffic through intersections more efficiently.
And they're right. Mythbusters confirmed this belief with anexperiment involving a large parking lot and a lot of traffic dividers. If you want a more academic authority, Kansas State University hasassembled studies that--like the Mythbusters--found traffic flows through roundabouts 20 percent more efficiently than it does through intersections with stoplights or stop signs. Roundabouts are safer as well--you can't "run" a roundabout the way you can a stop sign or red light.
Slot-based intersections, speed controlled by traffic algorithms using your cruise control, and self-driving cars are all great innovations and I can't wait to see them come into everyday use. But until that future arrives, I'm betting on the good old roundabout.