Corporate manslaughter

My Radio 4 piece is over and done, but I should have denounced the purveyors of traffic control in stronger terms. By making roads dangerous in the first place (with the unequal priority system), and for presiding over tens of thousands of avoidable deaths and serious injuries on the roads every year, should they be facing corporate manslaughter charges? In London alone, poor air quality kills 4000 people every year prematurely. The added pollution from idling needlessly in queues caused by traffic lights, and accelerating away from a standing start, multiplies fuel use and emissions by a factor of four (No Idle Matter). Whichever way you look at it, policymakers and traffic engineers have blood on their hands. For wasting our time and fuel, and for squandering tens of billions of public money on counterproductive systems of control, should they also be facing corporate lawsuits for damages?