It would be a huge mistake for cities to undo all the progress being made on human-scale street design.
The super smart folks at MIT’s Senseable City Lab have produced this great video of how an urban intersection might operate in a world of driverless cars. The smart, signal-free crossing offers everything we want from autonomous vehicles: fewer emissions, better traffic flow, less delay—all at a collision cost of zero. The MIT team visualized this “digital traffic controller” as part of a project called DriveWAVE:
Imagine a city without traffic lights, where lanes of cars merge harmoniously from one to the next, allowing traffic to flow smoothly across intersections. This futuristic vision is becoming reality. The development of autonomous driving promises to revolutionise the landscape of urban mobility.
DriveWAVE obviously isn’t meant for direct implementation onto city roads tomorrow. But the video raises a couple points worth acknowledging as we steadily move toward the driverless car era.
The first thing to notice is how truly terrifying it would be—at least initially—to ride in a driverless car going that fast through an intersection. Seriously: pause the video at 44 seconds and see how narrowly the car turning left avoids being slammed by another going straight. When you ride in a self-driving car, you quickly learn to trust it; in fact, Google has said its early test riders trusted the car too much on highways. But having faith in a computerized intersection overlord to orchestrate so much city traffic at such great speeds will require a steep period of public adjustment.
The second thing to note is far more important: Where are all the pedestrians and bike riders? (Hat tip to Columbia University planning professor David King for bringing this to our attention.) Keep in mind this wasn’t some remote crossing being modeled; it was the intersection of Massachusetts and Columbus avenues in Boston. Here’s the Google Street View, complete with cyclists and walkers:
There’s an obvious reason why an “intelligent intersection” would want to eliminate people crossing on foot or by bike: they’d slow things down. But it would be a huge mistake for cities to undo all the progress being made on human-scale street design just to accommodate a perfect algorithm of car movement. If the result is that driverless cars need to move through cities at sub-optimal speeds, then so be it. We won’t be losing as much productivity to traffic as we do today, anyway.
This isn’t to pick on DriveWAVE. It’s natural to model intersections as if cars were the only mode that mattered—especially when computer drivers make every move predictable. The driverless intersection we presented a few years ago, based on work from computer scientists Peter Stone and Kurt Dresner of the University of Texas at Austin, made the same assumptions: lots of cars, no people or bikes.
Again, these models and videos were meant to start a discussion about how to design urban intersections for a driverless future. They aren’t supposed to be a finished product. But the interactions between self-driving cars and every other city street user need to be considered at the very earliest phases of that planning process. The self-braking Volvo that recently failed to stop for a person is a great example of what might happen in the absence of strong regulation over the safety of our streets.
More broadly, cities need to be thinking about how to integrate driverless cars into their existing transit networks—either as a supplement to train and bus lines, or as stand-alone shared taxi fleets. The alternative is subverting the needs of city people to those of city cars, and we’ve seen that movie before.