A square “road” goes around the 30-ish steps line from the origin. Houses line the road, and trees are scattered around.
When the model runs, buses follow the road continuously. Houses have people who need to get to work. If a bus passes a house, that house’s person “gets on the bus” (resets the house timer). However, if a bus doesn’t come soon enough, the person will drive a car instead, which puts a car on the road that needs to travel a certain distance before being removed from the road.
Setup code determines the number of buses.
Cars emit 1 pollution every 7 “ticks”. Buses emit one pollution every 1 tick. Cars and buses follow basic traffic jam rules: slow down if crowded, and stop if there’s no room ahead to move.
The investigations involve figuring out how many buses need to be placed into service to keep air pollution as low as possible. A graph shows pollution levels over time.