When Slower is Faster
One theme that I found myself returning to again and again in Traffic is the often counterintuitive notion that “slower can be faster.” This idea comes up in any number of traffic (and network) situations — ranging from “ramp meters” at highway entrances, to the “speed harmonization” techniques used on motorways like the M25 in England, to individual drivers pacing themselves to avoid “driving into the jam,” to the practice (espoused by hyper-milers and eco-drivers) of not racing needlessly up to red lights, to getting rid of traffic lights and replacing them with roundabouts, which often seem slower but on average process more traffic than conventional intersections. As a study by Australia’s Monash University, titled “The Impact of Lowered Speed Limits in Urban and Metropolitan Areas” notes, even a lower speed limit can paradoxically produce faster traffic (particularly in “medium” congestion). The reason: “A lower speed limit may actually reduce overall travel time by allowing a more harmonic traffic rhythm.”
I was intrigued to come across a lo-fi, but effective, demonstration of this principle on YouTube (where a traffic subculture flourishes), using Martin Treiber’s excellent traffic simulator. As someone who constantly finds himself zipping past drivers at the lights— drivers who had moments before blazed aggressively past me — this is a nice example of how our own driving style helps contributes to traffic problems.
This entry was posted on Saturday, July 12th, 2008 at 4:43 pm and is filed under Congestion, Drivers, Traffic Engineering, Traffic Wonkery. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.