If I was an engineer I would build two things that would go together. The first thing would be building a wall by a roads intersection when the red lights are on. The wall will disappear when one side has a green light letting the other cars go, this way the people crossing the road will feel safer crossing the street. The second thing that goings with it would be to add a sensor to the cars, when the wall goes up, so the car won’t crash. This way there will be less crashes.