A world without traffic lights

Published on Wednesday, 25 May 2016

Urban streets as runways for airplanes and drones. With the increasingly rapid evolution of technology, this scenario - which today seems utopian - could become a reality in the not too distant future. So research is underway to develop management systems for the urban mobility of the future.

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With this in mind, the Enel Foundation has supported the work of a team of researchers from the Massachusetts Institute of Technology (MIT), the Swiss Institute of Technology (ETH) and the Institute of Informatics and Telematics of the Italy’s National Research Council (CNR), which has developed an innovative way to manage vehicular traffic that has the potential to replace traditional crossings with traffic lights, reducing traffic jams and delays.

‘Information and communications technology and self-driving cars will change the landscape of urban mobility,’ explains Carlo Ratti, director of the Senseable City Lab at MIT, where part of the study was conducted. ‘In a future in which all cars will be autonomous, is it possible to imagine vehicles no longer needing to stop at intersections, but that will continue to move without collisions?’

To answer this question, researchers have developed a new system for managing crossings inspired by air traffic control techniques, called the slot system. A personalised timeslot will be available for each vehicle to cross intersections - like airplanes on the runway - thus eliminating the need to stop that is typical of the traffic light system. In addition, the vehicle’s speed will be controlled so that each car reaches the intersection in correspondence with the slot that has been allocated using an algorithm and technologies already existing in many cars, allowing them to talk to each other.

‘The transition from the traffic light system to that of slots can substantially improve the efficiency of crossings,’ states Paolo Santi, a member of the MIT Senseable City Lab and researcher at the CNR. ‘Our analyses show that, with current traffic volumes, there were no more queues, and, with our system, delays in reaching a chosen destination could practically disappear.’

Slot intersections are therefore comparable to "smart roundabouts," in which the vehicle arrives at a slow speed, but is not forced to stop as is the case with intersections with traffic lights. Thanks to its flexibility, this system allows better traffic management not only for cars but also for pedestrians and bicycles. ‘The results obtained under the same safety conditions show that - compared to traffic lights – with the "slot" system the number of cars that the crossing can handle can be doubled. This implies a significant positive impact on the entire road network,’ says Dirk Helbing of the Swiss Institute of Technology.

The new system will also help reduce the wear of road infrastructure. Planning an urban space capable of supporting technological evolution, says Ratti, must necessarily start today. According to Ratti, ‘It is imperative to begin evaluating now the effect of self-driving vehicles on the city. The road infrastructure lifetime amounts to several decades, and therefore our streets will undoubtedly witness the arrival of self-driven vehicles and the resulting changes in the field of mobility.’

You can see the full results of the study on the PloS ONE magazine website.