To Reduce Traffic Jams, Minimize Randomness?
For countless commuters, traffic congestion is the bane of their existence. An unexpected jam can quickly foul moods and foil meticulously scheduled plans. Given the ubiquity of the problem and the near universal disdain for driving ten miles per hour on a sixty mile per hour highway, it's a wonder that more scientists haven't dedicated themselves to the task of alleviating road congestion.
Thankfully, Jay Combinido and May Lim, two physicists from the University of the Philippines Diliman, have come up with a suggestion for improvement. In roadway segments prone to a high density of motor vehicles, driving randomness must be reduced, they say.
Using the Nagel-Schreckenberg formula, a model used to simulate highway conditions, the two scientists examined numerous theoretical driving situations. They discovered that cars can move at constant, high speeds even in areas of high vehicle density, but it's the random fluctuations in driving speeds that primarily fuel stop-and-go traffic jams. They cited slow-moving vehicles (Sunday drivers) and those that frequently stop (such as public utility vehicles) as a couple of sources of this randomness, as they deviate from the average roadway speeds and cause others to clump up behind them. They also noted that traffic lights tend to boost fluctuations in driving speeds and thus potentially increase the likelihood of a jam.
One minor solution, they say, is to adopt median U-turns in place of left-turns. They also recommend that further research be conducted on a wider scale by deploying specialized traffic data collection apps to GPS-enabled smartphones. Now that's a citizen science project that people would want to take part in.
Source: Combinido JSL, Lim MT (2012) Crowding Effects in Vehicular Traffic. PLoS ONE 7(11): e48151. doi:10.1371/journal.pone.0048151