[mantas]

That'd be a disaster on single-lane roads. Even with human trucks and their help (signalling if road is clear, driving on the shoulder when possible etc), it sucks to overtake them. If trucks were limited to 70km/h, there'd be much more need to overtake them. Which would either cause either traffic congestion or more drivers doing reckless things. Let alone that non-driverless trucks/buses/campers/etc would be stuck behind them forever.

[massysett]

I imagine they would start out only on multi-lane, limited-access highways. The small number of entry and exit points would make it much easier to program the truck. Such roads carry the bulk of long-distance truck traffic anyway.

[mantas]

Once you get away from highly populated and developed areas, there're lots of single-lane roads. Let alone that single-lane roads are used as backups when inevitable accident happens on multilane. Of course, there's not as much traffic in such areas as in those with multi-lane highways.

[kuschku]

Well, the current tests with self-driving trucks are almost exclusively by european carmakers on German roads – where 2 to 3 lanes are common about everywhere, and trucks are limited to 80km/h or 100km/h anyway.