I recently read an article in a scholarly online journal titled “The Science of Traffic,” which summed up some of what I already knew and enlightened me about what I didn’t. Although it’s obvious to all drivers that traffic jams are occasionally engendered by lane-closing collisions or road work, or by infuriating rubber-necking at a minor fender-bender pulled over onto the shoulder, slowdowns are more often caused by something seemingly much less egregious: a slow driver.
That slow driver might be one of a variety of individuals: a trucker with a heavy load on an uphill incline, a new (or perhaps older) driver uncomfortable with the posted highway speed limit, or, most dangerous of all, a driver distracted by his or her smartphone, trying to read or respond to a text message. Regardless of the circumstances, the driver behind the slow vehicle is forced to either brake or change lanes – usually both. When he or she taps the brake, it forces the driver behind to do the same, creating a chain reaction in the drivers behind them – the “upstream” vehicles. This is referred to as a “shockwave.”
The slowdown invariably spreads across all other lanes, as vehicles attempt to get away from the slow driver by forcing their way over, causing drivers in that lane to brake, causing another shockwave – and so it goes. The slowdown gradually ends when the offending slow vehicle leaves the highway, crests the hill and returns to normal driving speed, or finishes the text and puts the phone down.
These are called “phantom bottlenecks.” Invariably, if a car hits the brakes on a crowded road, a shockwave will result, and there is no way to prevent this. Perhaps if we all exercised perfect self-control, avoided tailgating, and maintained enough distance between our car and the car ahead in order to be able to absorb a brake tap without being forced to tap the brakes ourselves, we could reduce the number of these infuriating phantom bottlenecks.
But we are not perfect and never will be. Ahh, but self-driving cars and the incredible technology they utilize just might come pretty close. No more slow vehicles to begin with, as highway speeds will be perfectly maintained; merges from on-ramps will be executed with ballet-like precision. There will be precise spacing between cars based on speed limits and road conditions. Minimal braking, safe lane-changes, the elimination of rubber-necking – all designed to get us to our destinations more quickly, more smoothly, and most important of all, more safely.
The technology is coming – and coming quickly. I, for one, can’t wait.