Though I’m very much for this kind of vehicle in principle, I’m not convinced of their safety, at least in heavy traffic.Comparing a driverless ground vehicle to an airplane on autopilot isn’t really a valid comparison, since the flight safety regulations are far more stringent than traffic laws are. For example, aircraft are required minimal lateral and vertical distances from the nearest other aircraft, substantial distances, particularly horizontally (three miles, as I recall a commercial pilot telling me, I think). I suppose if a driverless vehicle was programmed to maintain a safe distance between itself and the car in front of it (in any lane, where more than one lane flows in the same direction) I might feel better, but I haven’t read about any such feature. (It may be there and I simply don’t know about it, true.) Bettering the rule of thumb, I’d say a minimum of 1.5 average car lengths for each 10mph speed, with a vehicle moving ever slightly back as its speed picked up, rather than a sudden increase after 10 more mph have been added. 2X’s would be even better, IMO, a not entirely uninformed opinion, as I drove an 18-wheeler after taking a three-week training course, one driving on a converted airstrip, another week devoted to over-the-road driving with an instructor, plus I took high-speed driving training when I was in police-security work years ago. Stopping a fully-loaded 18-wheeler from 60mph with just six 18-wheeler lengths between me and a vehicle in front of me is a very iffy matter, if it’s even possible. In that case, we’re talking in the range of 100 yards.

I have read of potentially using driverless engines to pull elevated trains and subways at the city level, and that makes considerable sense. Especially if such a system includes constant human monitoring by someone with the ability to shut down the train immediately should the “autopilot” fail in any way. That might help us gradually increase our comfort level with the idea.

Good article, Mr. Ho — thanks.