Meeting on a narrow road
Jean-Louis Gassée, while a respected computer entrepreneur, wrote a critical post on robocars recently which matches a very common pattern of critical articles:
The pattern is as follows:
- The author has been hearing about robocars for a while, and is interested
- While out driving, or sometimes just while thinking, they encounter a situation which seems challenging
- They can't figure out what a robocar would do in that situation
- They conclude that thus the technology is very far in the future.
His scenario is the very narrow road, so narrow that it really should be one-way but it isn't. In most of the road, two cars can't pass one another. Humans resolve this through various human dynamics, discussion and experience.
In most of these examples, the situation is not one that is new to robocar developers. They've been thinking about all the problems they might encounter in driving for over a decade in many cases. It's extremely rare for a newcomer to come up with a scenario they have not thought of. In addition, developers are putting cars on the road, with over a million miles in Google's case, to find the situations that they didn't think of just by thinking and driving themselves. It is not impossible for novices to come up with something new -- in fact a fresh eye can often be very valuable -- but the fresh eyes should check to see what prior thinking may exist.
Some of the problems are indeed hard, and developers have put them later on the roadmap. They will not release their cars to operate on roads where the unsolved situations may occur. If snow is hard, the first cars will be released in places where it does not snow, or they will not drive on their own if it's snowing. In the meantime, the problems will be solved, in a priority order based on how often they happen and how important they are.
The "two cars meet" situation involves very rare roads in the USA, so it's not a high priority problem there, but it would not be a surprise problem. That's because current plans have cars only drive with a map of the road they are driving. No map, they don't drive the road.
That means they know the road well, and exactly how wide it is at every spot, and what its rules are (one-way vs. two-way and so on.) They will know their own width and the width of oncoming vehicles accurately. If they can't safely drive a road, they won't drive it. If it's a rare road, the cost of that will be accepted. Driving every road everywhere is a nice dream, but not necessary to have a highly useful product. While Google's ideal prototype is planned to be released for urban situations without a wheel, cars that need to go places where they can't drive will continue to offer wheels or other interfaces (joysticks, tablet apps) that let a human guide them to get through problems.
The two-cars meeting problem is interesting because it's actually one where the cars can far outperform humans. It's also one of the rare times that communication between cars turns out to be useful. (Typically car to server to server to car, not direct v2v, but that's another matter.)
The reason is that super narrow roads, including country roads and urban back-alleys have occasional wide-spots and turn outs where people can pass. They have to, to be two-way. And these will all be on the map. Cars on such a road would desire traffic data about other cars on the road. They will be able to make predictions about when they might encounter another car coming the other way. Most interestingly, one or both of the cars can adjust their speed so that they will encounter one another precisely at one of the wider spots where passing can take place.
In fact, if they do this well, they might drive a one-lane road at a nice fast speed, barely slowing down in these wider passing zones, in part because by knowing the width of the vehicles they will be able to confidently pass quite closely. If a robocar is meeting a human driven car, it would leave some slop, picking the right passing zone, arriving early in case the other car is faster than expected, waiting if it is slower.
This remarkable ability would allow us to build low-traffic roads and alleys which are mostly only one lane wide, but which could carry traffic fairly quickly and safely in both directions. Gassée's problem is far from a problem -- it's actually a great opportunity to vastly decrease the cost and land requirements of road construction. I wrote about this a couple of years ago, in fact.
Even without communication, a robocar would do pretty well here. Its map would tell it, should it encounter another vehicle on the road it can't pass, just where the closest passing spot is. It could back up if need be, or if the other car should back up, it could nudge in that direction, or even display instructions to a human driver on a screen. It would be able to do this far better than humans could because of its accurate measurements and driving ability. Generally, any human car should defer to the robocar's superior knowledge and superior ability to manage a close pass-by. The car would figure it out the moment it sensed the other car, and immediately adjust speed to meet at a passing point, or possibly to back up. Unlike humans, they will be able to drive in reverse at high speed if they have 360 degree sensors.
Human drivers could actually play a role in this. Those running a mobile app like WAZE could know about other cars running the app, or robocars. The app could give them advice to speed up or slow down to encounter the other car at a wide spot. Of course, if there are cars not using the app, they would just fall back to the old fashioned human approach. One could imagine a sign at the entry to a narrow road saying, "We recommend running the XYZ app for a smoother trip down this road."
Not all these problems that people put forward were as easily resolved as this one, so I am not calling for people to "shut up and let the experts get to work." There are many problems yet to be solved. Most of them can be be solved by punting because you don't need to drive everywhere. Though Google has shown that having a steering wheel that can be grabbed while moving is a bad idea, I do expect most cars to have some form of control that can be activated when a car is stopped. If a road needs the human touch, it will be available.