We typically think of traffic jams as a problem that has to do purely with the quantity of cars on the road. But it's not quite that simple. In fact, in San Francisco's metropolitan region there's a small group of drivers that is creating traffic jams for everyone else. The San Jose Mercury reports:
These commuters aren't necessarily slow or bad drivers. Instead, they come from a few outlying neighborhoods and travel long distances together in the same direction like schools of fish -- clogging up not only the roads they drive on, but also everyone else's.
How do we know this? Data.
A group of researchers from the University of California Berkeley and MIT used anonymous data from the cell phones and GPS systems of 350,000 Bay Area drivers with a goal of determining what causes traffic jams. The study concluded that if you cancel or delay the trips of 1 percent of all drivers in a region, traffic congestion would be relieved by 3 percent. However, using traffic data to determine the small pocket of drivers that do the most to cause traffic jams, the researchers found that canceling the trips of 1 percent of those drivers resulted in decreased travel times of 18 percent for all drivers across the metro area.
“This is a preliminary study that demonstrates that not all drivers are contributing uniformly to congestion,” said co-author Alexandre Bayen, an associate professor of electrical engineering and computer science and of civil and environmental engineering at UC Berkeley, in a statement. “Reaching out to everybody to change their time or mode of commute is thus not necessarily as efficient as reaching out to those in a particular geographic area who contribute most to bottlenecks.”
The San Jose Mercury reports that local transportation officials plan to use the study to implement measures such as metering lights to spread out traffic volume in the metro's most congested areas.
Key source of Bay Area traffic headaches revealed by top researchers [San Jose Mercury]