Cars are driving (very fast) over a bridge. They cannot pass each other on the bridge. The buttons set the number of cars moving in each direction. The default is to have two blue cars going in each direction.
As you see, the car drivers are not as careful as they should be!
There are three polices for a bridge. The default does not provide any safety for cars. Modify the class skeletons SafeBridge and FairBridge so that they provide safe and fair policies for crossing the bridge.
Hint for safety: keep track of the numbers of red and blue cars on the bridge.
Hint for fairness: keep track of numbers of waiting cars and whose turn it is.
Warning: due to much repainting of the scenery, the buttons do not react very quick.
Safe and Fair bridges are demonstrated here