It’s a frustrating common occurrence; after struggling along through dense traffic for minutes on end, a driver arrives at the front of the traffic jam only to find nothing at all that could account for the delay. Or, a driver passes serious congestion going the other way but cannot see any reason for it—no accident, no construction zone, nothing. Could the traffic have snarled itself up spontaneously?
Apparently, spontaneous self-snarling is exactly what happens much of the time, according to a new study funded by grants from the National Science Foundation. Among their conclusions is that momentary breaking, or even just a slow-down, by a single car for any reason—debris in the road or a moment of inattention—can trigger a chain reaction that builds into a so-called phantom traffic jam. Say one driver notices she’s unintentionally speeding and slows up a bit, perhaps over-correcting. The driver behind sees red lights ahead and steps on the break a moment, as a precaution. So do the next drivers in line. And because none of these drivers can react instantaneously, the slow-down tends to build as it moves back from one driver to the next, causing what the researchers refer to as a “wave of high vehicle density.”
The technical term for a traffic jam for this kind of no good reason is “jamiton.”
While it’s easy to blame jamitons on some failure on the part of the lead driver, experiments have shown that phantom jams, or even whole strings of one jamiton after another, form even when all the drivers do everything right and in exactly the same way. In fact, a moment’s thought suggestions that this same phenomenon is actually helpful; drivers looking to cross or merge into other lanes of traffic look for gaps, open places in the line of cars and these open places must be balanced by dense places elsewhere in the traffic flow—jamitons.
Useful or not, jamitons can cause accidents and they definitely cause frustration and unnecessary delay. Truck drivers can avoid them by using the routing software available through fleet management companies. The software feature can notify drivers of areas of traffic congestion ahead (whether there is a good reason for the jam or not) and even help the driver detour around the blockage. If the truck does get stuck in a large and truly unavoidable jam, real-time GPS tracking and two-way communication allow the fleet manager to adjust the time table so that the driver is not tempted to speed later to make up the difference.
Adjusting the route and the time table according to current conditions on the road is part of making trucking smarter and more flexible. By keeping trucks out of jamitons (and other types of heavy traffic) wherever possible, routing software helps ensure that more of a driver’s minutes behind the wheel translate into miles under the wheels. That means more money in everyone’s pocket.