back in the 70s after the arab oil embargo, the US govt brought in the 55mph speed limit on the highways, and the overall #of traffic fatalities dropped significantly.

regarding the left and right side of the road..
(thread drift)
my grandfather drove an oxcart for a brewery in wartime Czechoslovakia.
THe Czechs drove on the left as in England, but when the Germans came they immediately switched all traffic over to the right.
Which was ok for vehicles, but the darned oxen kept going over to the left side. Eventually they got to an intersection where a german soldier yelled at him to get them over to the right, he gave up and handed the reins to the soldier and walked away.