WE SLEEP AT HOME and work at the office. But we live on the road—in our cars and buses and trains, on our bikes or feet or scooters or skateboards. Transport and traffic shape our days, our environment, even our politics. Read how you can beat the traffic, avoid it, or live with it—whatever you ride or drive.
WHY TRAFFIC BACKS UP
Traffic is remarkably complex; scientists use game theory, chaos theory, fluid-flow theory, even string theory to explain it. Mark Hallenbeck, director of UW’s Washington State Transportation Center, prefers what he calls the Wile E. Coyote Theorem.
Coyote chases Road Runner off a cliff—and keeps running, untroubled, until he stops, glances down sheepishly, and plummets to earth. Likewise, says Hallenbeck, freeway drivers routinely perform the impossible, as long as they don’t notice they’re doing it.
In theory, maximum traffic flow is about 2,000 vehicles per lane per hour, which allows two seconds’ stopping distance between each. But morning rush-hour volumes reach 2,400 vehicles. Then something happens: an accident, a traffic stop or breakdown, a catchy billboard. One driver slows to gawk. The next driver must brake harder to avoid colliding, the next one harder still. The faith that kept them going at untenably close distance is broken. “The coyote looks down and he’s screwed,” says Hallenbeck. “Ten cars later, you have a traffic jam.”
You don’t need an awful lot of people to get congestion: Richland, population 45,000, has 15-minute morning and afternoon rush “hours.” In larger cities, notes Hallenbeck, “the peak spreads until it’s no longer two peaks. It’s flat”—like Highway 520, filled to capacity throughout the day.
“Given the opportunity, people will all go to work at 8am and return at 5. Companies like you there at 8, and no one wants to go early.” That’s why adding highway capacity doesn’t eliminate congestion. Commuters shift their schedules to drive as near as they can to the preferred time. Given the chance, says Hallenbeck, “they’ll all go again at 8. If you truly wanted a congestion-free I-5 with people going whenever they want, you’d need about 22 lanes in each direction.”