1. At what density does a phantom jam appear? The ring is started from perfect spacing with one car nudged by half a metre. The sweep measures how fast the disturbance grows for each number of cars and compares it with the linear-stability prediction of the model.
2. Which cycle length minimises delay? The junction is simulated for an hour at each cycle length (green split from Webster) and compared with Webster's formula and his optimum cycle.
3. Signals or roundabout? The same demand on four approaches is pushed through both designs from light to heavy traffic. The sweep finds where each design saturates and where one overtakes the other.
4. Roundabout entry capacity. One saturated entry against a random stream of circulating cars, compared with the gap-acceptance formula (Cowan M3).
Press a button. The driver settings of the panel are used; the sweeps run in your browser and take a few seconds.