MIT researchers plan "death of the traffic light" with smart intersections


A group of researchers has developed a conceptual traffic system that would enable driverless vehicles to whizz through intersections without colliding, eliminating the need for signals (+ movie).

Light Traffic by MIT researchers
Each car enters a designated slot. Sequence one – click for larger image

Researchers from MIT, the Swiss Institute of Technology and the Italian National Research Council came up with the idea for a new type of intersection called Light Traffic.

Their system would use sensors to keep driverless cars at a safe distance from each other and allocate each car with a crossing slot as it arrives at a junction.

Speeds would be automatically adjusted on approach to ensure the vehicles take it in turns to pass across without having to stop.

"Traffic intersections are particularly complex spaces, because you have two flows of traffic competing for the same piece of real estate," said Italian architect Carlo Ratti, director of the MIT Senseable City Lab.

Light Traffic by MIT researchers
Vehicles go to an intersection when there is a slot available for them. Sequence two – click for larger image

"But a slot-based system moves the focus from the traffic flow level to the vehicle level," he continued. "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 team believes that this system could dramatically reduce the amount of pollution emitted by waiting vehicles, which would be burning fuel unnecessarily.

It also claims that twice as many cars would be able to pass through crossings in the same amount of time as at intersections controlled by traffic lights.

Light Traffic by MIT researchers
MIT claims that twice as many cars would be able to pass through crossings in the same amount of time as at intersections controlled by traffic lights. Sequence three – click for larger image

This would help alleviate congestion, extend the lifespan of current infrastructure and reduce the need for new roads.

"It is important that we start looking into the impact of self-driving vehicles at the city level as soon as possible," Ratti said. "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."

Subscribe to Dezeen's YouTube channel for the latest architecture and design movies

MIT described the project as heralding the "death of the traffic light".

Companies ranging from Bentley to Google are working on plans for driverless cars. Goodyear recently unveiled a design for a spherical tyre made for smart vehicles.

At this year's Geneva Motor Show, Nissan and Foster + Partners unveiled a vision for a connected network that would enable autonomous vehicles to power homes.

  • max

    Ever heard of roundabouts?

  • Ciarán Ferrie

    And where do the cyclists go? And the pedestrians?

    • Thomas


    • I was wondering the same thing.

    • Biker

      With driverless bikes, obviously (insert sarcasm).

    • deadlikeme74

      To a park, where they belong.

  • bitterbuffalo

    I had the same question as Ciarán. This might be great for future highway interchanges, but it shows absolute contempt for anyone not in a motorised steel coffin.

  • London Texas

    The death of traffic lights heralds the death of pedestrians.

  • dick_c

    If we can ever manage driverless vehicles I doubt assigning “slots” to pedestrians and bicyclists will be much of a problem.

    • Will there be differently timed slots for able-bodied and limited-mobility pedestrians? How long will the latter have to wait before there’s enough of a slot in the pipe for them to cross, and what will happen if they take longer than assumed? The system will lose its efficiency.

  • gneiss

    Nice how there are no markings at the intersection for pedestrian crossings, nor any discussion about how they are integrated into a “traffic” system.

  • Pol Clusella Arimany

    Great! And what about people? This is absurd, get a bike.

  • some1s_lucky

    If only MIT researchers invested their time in teleporters! Not only would there be no need for traffic signals but there would also be no need for cars! Next, commence research in obesity due to the lack of physical activity!

  • janine

    It is essentially a mini train proposal.

  • tomwest

    Doesn’t this require *every* vehicle be autonomous?

  • 1976boy

    I guess driverless cars would also be able to detect pedestrians and stop. Thus, anyone could cross at any point, intersection or not, and the cars would yield. This gives peds a lot of power. It also undermines the stated goal of this model, which is absurd: the elimination of “traffic”.

    • Ninja250

      New game for teens – see how many driverless cars they can back up by continuously crossing the street!

  • Stf

    Underground might work.

  • Camden Greenlee

    A lot of critical comments here. I think we should commend the research, not as it ultimately applies to real-world applications, but as a step towards solving a complicated problem.

    In research, it is often very useful (particularly at the beginning of a process) to distill down to some manageable amount of variables so that real relationships can be identified. So, the fact that pedestrian and bike traffic has not been considered here is no surprise, and in my opinion, not an appropriate criticism of the researchers.

    • Joanne Stevens

      This is just a proof of concept I suppose, but the concept has already been proven. The principle of reserved slots (or “blocks”) is almost as old as the railways, and all of the stuff in their computer model about moving blocks, speed adjustments and safety margins is already happening in real-world metro systems.

      Applying these rules to driverless cars in a computer model is an important first step, but it’s not really research as such. Now they have a model they can start solving real world problems.

      Problem 1: how to adapt the principles of a closed network (trains only, and only by permission of network operator) to an open one (cars, pedestrians, bicyclists, children, deliveries, dogs etc… anybody and anything at anytime)

  • Ruben Arce

    Watched the video. Not only is there no allowance for cyclists or pedestrians, there is also no allowance for passengers.

    The vehicles make right-angle turns without any sign of slowing down. Imagine being in one of these. Must be how they were able to claim such an improvement.

  • Ninja250

    Ahhh, finally it comes out that the taxpayer will have to support billions of dollars of infrastructure improvement to make “self-driving” cars practical (or at least profitable for the auto companies).

  • Funny. A world without humans. Roads for cars only. As far as I can tell, the best transit tools available to planners today are “complete streets”. Anything that kills that, kills transit for humans.
    Some “studies” should just be shelved right after inception. I don’t see how far they can go with this from here.

  • WalterINDY

    Dear MIT, we no longer design streets for optimal speed and efficiency of cars. That was the 1960s. So stop it, and get with the 21st century.

  • Frank A. Coluccio


    After re-reading and further mulling the description of this light traffic scheme, I recognized several principles used in early digital transmission schemes: statistical time division multiplexing (STDM); and, time-slot interchange (TSI).

    “MIT claims that twice as many cars would be able to pass through crossings in the same amount of time as at intersections controlled by traffic lights.”

    An early analog (quasi-digital) transmission system used in submarine cable systems, which used the available pause time between syllables of one talker to insert syllables of speech from other talkers, was dubbed TASI, standing for time-assignment speech interpolation. Plus ça change…

    What would be the privacy implications of a system that could grab a car by the horns and direct it through traffic. Added to cameras, GPS-enabled schemes of an unending variety, bar-code readers, I/R scanners and microscopic sensors that fill every void… it’s not difficult to imagine the emergence of a market for false identities through the use of digital proxies prospering before long.

  • Kay

    Driverless cars are going to change everything about the way we design and experience cities. This research should be applauded. Looking forward to seeing more.

  • deadlikeme74

    Obviously, pedestrian traffic has been outlawed in the driverless-car society. Since you don’t have to drive, you just ride everywhere – people will become even more dependent on cars to get everywhere.

  • Interesting thoughts.

  • Paul Miller

    Roundabouts are in my opinion (25 years as transportation consultant) are the only intersection control that safely manages all modes of travel in the future. The driven vehicle, be it a motorised or human-powered vehicle without automated controls will rely on human biology to control the vehicles travel.

    Until the last driven car is banished from the national roadway system, ALL traffic signals will need to remain for this last human controlled vehicle. I call this my “Last Red Corvette” problem. However, a roundabout with its engineered slow-speed vehicular merging zones can safety manage ALL forms of human and autonomous travel.