Tailgating won’t get you through that intersection any faster

You’ve stopped barely a hair’s breadth away from the car in front of you at a traffic light, hoping to get through quickly when the light changes. But you won’t. Instead, a new study suggests you’ll take just as long as an auto stopped up to two car lengths behind the lead driver. To find out whether tailgating pays off, researchers lined up 10 sedans at a traffic intersection on a test road, such that they stood different distances apart each time. A drone hovering above the intersection recorded the cars moving as the light turned green. Just as it takes time to heat a solid ice cube before it starts melting—a thermodynamic concept called latent heat—there’s a time lag before you can safely accelerate your car in a solid jam, offsetting any advantage of closeness, researchers reported last week in the New Journal of Physics . A car standing up to 7.6 meters back speeds up and covers the extra distance in about the same time it takes the tailgating car, with both crossing the intersection at the same time. That suggests your driver’s education teacher was right all along: Maintaining a safe distance at traffic lights won’t slow you down, and it has the added benefit of reducing your chances of rear-end collisions. But think again if you’re waiting in a line full of people. Because pedestrians are slower, the time delay becomes insignificant, making a closer-packed line move quicker.