The introduction of the much-heralded self-driving car has incredible potential to redefine and reshape our cities, from urban planning decisions to the design of our roadways. But, according to new work by MIT researchers, the shift to robotic vehicles may eliminate something as seemingly fundamental as human drivers; the stoplight.
In a paper published in the journal PLoS ONE on Wednesday, "Revisiting Street Intersections using Slot-Based Systems,” a team of MIT scientists, and their colleagues at the Swiss Institute of Technology (ETHZ), and the Italian National Research Council (CNR), proposed a new means of directing traffic, slot-based intersections, which communicate with sensor-laden autonomous vehicles to sort traffic, replacing stoplights with precisely directed streams of vehicles. The system could double the number of cars that could safely use an intersection.
“Traffic intersections are particularly complex spaces, because you have two rows of traffic competing for the same piece of real estate,” says Professor Carlo Ratti, Director of the MIT Senseable City Lab, which initiated the study. “But a slot-based system moves the focus from the traffic flow level to the vehicle level. Ultimately, it’s a much more efficient system, because vehicles will get to an intersection exactly when there is a slot available to them.”
The benefits would go beyond increased efficiency. As wait times at red and yellow lights disappear, energy and gas usage, as well as travel times, would shrink. The economic and environmental impact could be sizable in a big city, not to mention the mental health benefits of not stewing in traffic.
“It is important that we start looking into the impact of self-driving vehicles at the city level as soon as possible,” added Ratti. “The lifetime of today’s road infrastructure is many decades and it will certainly be impacted by the mobility disruptions brought in by new technologies.”