at the danger from collision at those speeds. Clearly, speed limits in residential and urban / suburban areas need to be limited to 20 mph. Permeability for cyclists and pedestrians in residential areas, access only for motor-vehicles. There's an often quoted but unsourced quote from Bakunin that states: "By striving to do the impossible, man has always achieved what is possible. Those who have cautiously done no more than they believed possible have never taken a single step forward."