About self driving cars…


Self-driving cars are one of the these impressive science-fiction ideas, that are nowadays technically possible, will we soon see such cars around? Wide deployment depends on two things: that such car work, and that society accepts them, both socially and legally. In my opinion there is a significant legal problem in self driving cars: they will need to respect the law.

One of the theoretical aspects of the driving exam in Switzerland is breaking distances. The rule says that it should be the distance covered by the car in two seconds. When driving on a highway at 120 Km/h (33⅓ m/s), this represents 66 meters. This distance is meant for perfect conditions, in case of wet roads, it should be increased.

Take any crowded highway and you will notice that the distance between cars is much smaller. Strictly speaking, all these cars are not respecting the law, but that law is not really enforced, so nobody cares. In case of accident, the guy behind is generally responsible, and the average driver seems OK with this risk. Same goes for speed limits: people drive faster that the limit, and live (and die) with the risks and the consequences.

Now introduce self driving cars into the picture, the first obvious question that will arise is: who is responsible in case of accident? When the car is driving by itself, it can hardly be the driver, so the ultimately the manufacturer of the car will be responsible. Of course, there will be clauses that waive that responsibility in case of unavoidable accidents (say a bridge collapses), but such waiver will imply that the car strictly respects the law.

So such cars could not drive fast on a crowded highway, because they cannot legally do so, the car would slow down until the distance between cars is safe, if the distance between cars is 10 meters, the maximum speed is 18 Km/h. So while you would not need to drive your car, it would go slower than an electric bicycle. You might as well take the train.

The law can be changed, in particular for self driving cars that have more advanced sensors, can coordinate with each others. This will require some serious work, both on the legal front and the technical front. So while self driving cars are technically possible, I don’t expect them to be usable in real european traffic soon…

5 thoughts on “About self driving cars…”

  1. If all cars were self driving on highways, we could manage. They would all go at 130 km/h, with perfect coordination and less security distance, obeying blindly whatever says the traffic authority to improve the flow (the law will change obviously). That would be a dream in crowded cities rings.

    But we’re stuck with people-driven cars for at least one generation, and so we have little incentive to buy a car with a brain that will be useless until there is enough of them to forbid people-driven cars on highways.

    So we’re stuck in traffic jams for a long time…

  2. If you need to build the control infrastructure, you might as well load the cars on a train. You might even get better energy efficiency: metal wheels instead of rubber…

  3. With fully automatic cars, the control infrastructure will be the 5G network and a few servers from the road authorities, telling each car how quick it must go, depending on the traffic and where the car wants to go. No need to change the current network, add rails, buy trains, and build huge railway stations that would become new bottlenecks. When a car leaves a big road, it goes back to manual control.

    I don’t know if this is doable before long. Even with fully automatic cars, there will always be failing cars. And, as I said, making the automatic control compulsory on these roads will meet strong resistance. I suppose it will happen very gradually, once the central authorities are in place.

  4. It is possible, but again, phone networks are best effort. Building a external control system would require:
    • A multi-national, multi-manufacturer standard for control.
    • Driving software that is legally valid internationally.
    • A real-time control network.
    • A real-time control system.
    • A legal framework to handle the privacy implications.
    All these things will have to be legally accepted and certified. This is going to be expensive and long, why do you think trains are so expensive? One of the reasons is that such infrastructure was built…

  5. – Communication network: already in place, at least on big roads where external control would be useful.
    – International support for control: possible, the biggest problem being the very slow turn-over of cars (you cannot forbid even 10 years-old cars to go on motorways, we’ll have to wait at least 20 years)
    – Driving software will be provided by Google if not ReNault or Volkswagen. It does not have to be the same everywhere, as central control will be coordination (drive at such speed on this lane, avoid obstacle here) and the car will drive alone with its own “will” (and capable of staying in the flow and parking itself even with communication off, central control down, and a dead driver, at least on “managed” roads), almost like planes today.

    You’re right saying that the legal framework and the certification process will be a big headache, perhaps the biggest. If an accident occurs when central control is down, all cars are on automatic control, whose insurance will pay?

    As for the trains: there is only one driver, one central authority, and everything legal is settled for ages. The cost is the physical infrastructure (rails) and trains themselves. Self-driving cars with a central authority would not need a new road infrastructure (and it must remain so to stay compatible with the small roads), and vehicles themselves were always paid by the customer.

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