More theories of traffic

I’ve mentioned before, though not for a while, that I used to travel around quite a bit, and sit in traffic quite a lot, and we used to discuss this idea. # 6 on the NY Times list of 32 Innovations That Will Change Your Tomorrow.

Traffic jams can form out of the simplest things. One driver gets too close to another and has to brake, as does the driver behind, as does the driver behind him — pretty soon, the first driver has sent a stop-and-go shock wave down the highway. One driving-simulator study found that nearly half the time one vehicle passed another, the lead vehicle had a faster average speed. All this leads to highway turbulence, which is why many traffic modelers see adaptive cruise control (A.C.C.) — which automatically maintains a set distance behind a car and the vehicle in front of it — as the key to congestion relief. Simulations have found that if some 20 percent of vehicles on a highway were equipped with advanced A.C.C., certain jams could be avoided simply through harmonizing speeds and smoothing driver reactions. One study shows that even a highway that is running at peak capacity has only 4.5 percent of its surface area occupied. More sophisticated adaptive cruse control systems could presumably fit more cars on the road. Tom Vanderbilt

When a quarter of the vehicles on a simulated highway had A.C.C., cumulative travel time dropped by 37.5 percent.

In another simulation, giving at least a quarter of the cars A.C.C. cut traffic delays by up to 20 percent.

By 2017, an estimated 6.9 million cars each year will come with A.C.C.

Via Kottke

More theories of traffic

Watching the paint dry

ink_truck_crash_030911-thumb-608x391-35226

I always wanted to know what would happen if a truck carrying printer cartridges crashed, and it happened in my relative backyard!

Approximately 16,000 pounds of ink cartridges from the Flint Group, an Indianapolis-based company selling printing and packaging products, was bound for a newspaper company in Portland, Maine. Red, blue, and yellow ink cartridges were inside the truck, but Ferson said there is no evidence the yellow ink was released.

Via Wired

Watching the paint dry

Fake Traffic Explained

I’ve written before about “Fake Traffic” and a developed theory called “The Wave Theory of Traffic” and I’m happy once again to write that scientists have used math and science to prove that ‘Phantom’ Traffic Jams exist and they’re working to mitigate them.

The MIT team found speed, traffic density and other factors can determine conditions that will lead to a jamiton and how quickly it will spread. Once the jam forms, the researchers say, drivers have no choice but to wait for it to clear. The new model could lead to roads designed with sufficient capacity to keep traffic density below the point at which a jamiton can form.

Via Boing Boing.

Fake Traffic Explained

The Wave Theory of Traffic

While driving in the US is down a little bit, traffic and congestion is down a lot.

[T]raffic congestion is subject to a tipping point–what economists call non-linearities. Add an additional car to a crowded road at rush hour, and traffic slows down a bit, and then the “carrying capacity” of the road declines. Traffic engineers estimate that most roads carry their maximum throughput — number of vehicles per hour at about 40 miles per hour — so as traffic slows below that speed, the road actually loses capacity and goes slower and slower, producing a traffic jam.

When we were touring we were incessantly sitting in traffic, usually at 6 PM when we were late for load in or at 3 AM when we were driving at night to avoid traffic. The guys up front staring blankly out the windshield at the cars and trucks snaking in the distance, the crushing reality of the digital clock cutting short soundcheck and possibly dinner. The guys in the back were only mildly aware that we weren’t moving, knowing that while we should be somewhere by now, we weren’t, and it only really mattered if we missed dinner, anyway.

Once in a while, there would be a pileup or emergency vehicles or construction. But more frequently, we’d be sitting in brutal, mind numbing traffic, and all of a sudden, it would clear up and we’d be moving again. We called this phenomenon “Fake Traffic” and eventually worked out a complicated and detailed Wave Theory of Traffic. And now, via Matthew Yglesias, CEOs for Cities have gotten to the bottom of this theory for us. Thank you CEOs for Cities!

The Wave Theory of Traffic