Stop & go — but mostly stop

by September 17, 2010

Traffic engineers have gone to great lengths over the years to figure out how to time stop lights so that the flow of cars and trucks can be maximized. Most such efforts have been based on average traffic loads observed at different times of day, but in the end it is almost impossible to find a smoothly-flowing city street because no real traffic load is ever actually “average”. So two professors working with the Santa Fe Institute, Dirk Helbing of the Swiss Federal Institute of Technology Zurich and his colleague Stefan Lämmer from the Dresden University of Technology in Germany, decided to turn things on their head: instead of having traffic respond to stop lights, what if stop lights responded to traffic? You can read the results in this ScienceNews report (or in their working paper), and at the bottom of Stefan Lämmer’s page (here), there is a side-by-side video in helicopter-flyover style showing simulated traffic flow in Dresden, and the real (but visually subtle) benefits of “self-stabilizing decentralized signal control”.