By broad point was not really clear, but could simply be stated as: We will make a lot of assumptions about what is a linear expense, linear threat etc. withou

By broad point was not really clear, but could simply be stated as: We will make a lot of assumptions about what is a linear expense, linear threat etc. without really knowing what will be linear until we pack an extremely tight grouping of cars on the road. Taking my point further: For road work, expense may go from linear to nonlinear because of something that seems completely counterintuitive. Imagine every car now has variation in the exact placement within the lanes. Highways have marks where the majority of cars drive, but variation in drivers accounts for variation in path. If every robot executed their driving in the exact 1 foot per tire space, it is likely that 1 foot per tire space would require a greater than linear road work. This could be solved by programing an automatic variation in all cars or possibly changing how roads are built so that they require only cement in those 1 foot areas. Now, an example of a time when engineers thought they had it right, but didn’t think of everything: Engineering has come a long way since the Tacoma bridge incedent, but we cannot underestimate what assumptions were previously made that will be incorrect when we start driving far more vehicles on roads. In the Tacoma bridge edge case, sustained winds caused flutter (self-feeding vibration) which caused the bridge to fail. While I do not suggest this is a likely case, the fact is, we are probably not considering everything and there will be issues we do not foresee, but we should try to eliminate as many edge cases as possible. http://www.youtube.com/watch?v=j-zczJXSxnw http://www.youtube.com/watch?v=j-zczJXSxnw http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940) http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940) To your point about robots being faster: Yes, I agree they are faster, but even the fastest robot will need some space to interact. In a situation where a truck on the highway has a blowout which causes large debris to separate from the truck, the robots still need some room to slow down. In the extreme example where cars are 1 foot away from each other, an accident like that would have tremendous negative consequences that even robots would have a tough time dealing with. We will have self-driving cars, and they will likely be much safer than human operated cars, but we are going to also have setbacks and many of them can be avoided by looking to the future and trying to solve the problems early rather than later.