If all drivers were polite, they would get where they're going faster

May 23, 2006
traffic

A new study from the University of Michigan found that traffic metering systems that incorporate new algorithms for merging could reduce the seriousness of traffic slowdowns that originate near freeway on-ramps.

Craig Davis, a retired Ford Motor Co. research scientist and current adjunct professor at U-M, studied highway merging to see how current on-ramp traffic meter systems could be made more effective. Currently, meter systems try to improve traffic flow by letting a certain number of cars enter the highway each minute based on how many cars are already there. Traffic metering has been around for a long time and many large U.S. cities have metering systems, Davis says.

Davis says there are two basic types of traffic congestion: gridlock-type jams where cars stop; and the synchronous flow-type congestion, where two or more lanes of traffic all slow down to the same speed. Synchronous flow happens often near on-ramps, when cars don't give one another enough room to merge, or when too many cars are on the road.

Metering systems use computer algorithms to try to predict when a jam may occur, typically based on occupancy. Davis, however, based his algorithm on the throughput and the rate at which vehicles are merging, not on highway occupancy. He found that traffic jams happen when throughput exceeds about 1,900 cars per hour per lane, and after that capacity drops by 10 percent or more.

Davis says in the absence of metering systems, simple politeness would go a long way toward thinning the sludgy traffic near on-ramps. But, letting people merge is helpful only if you don't slow down too much to do so.

"If you can do it without slowing down very much, that allows the driver who's entering to enter at a higher speed," Davis said. "If they have to crawl along waiting for an opening, they slow down the other vehicles on the freeway."

If you can safely move over a lane and allow a vehicle merge, that is even better, he adds.

Davis has received much attention for his research on automatic cruise control, a separate but related area of traffic congestion research. With ACC, onboard computers keep the correct distance between cars. Such systems have been shown in computer simulations to reduce traffic jams in throughput lanes, but don't do much to lessen the problem that is caused by merging near on-ramps, he says.

Source: University of Michigan

Explore further: History books spark latest Texas classroom battle

add to favorites email to friend print save as pdf

Related Stories

US judge fines HP $59 mn for bribing Russian officials

1 hour ago

A judge on Thursday ordered US computer giant Hewlett-Packard to pay $58.8 million for bribing Russian government officials to win a big-money contract with the prosecutor general's office in that nation.

Solar storm heads Earth's way after double sun blasts

1 hour ago

Two big explosions on the surface of the sun will cause a moderate to strong geomagnetic storm on Earth in the coming days, possibly disrupting radio and satellite communications, scientists said Thursday.

US threatened Yahoo with huge fine over surveillance

2 hours ago

US authorities threatened to fine Yahoo $250,000 a day if it failed to comply with a secret surveillance program requiring it to hand over user data in the name of national security, court documents showed ...

Microbes evolve faster than ocean can disperse them

2 hours ago

Two Northeastern University researchers and their international colleagues have created an advanced model aimed at exploring the role of neutral evolution in the biogeographic distribution of ocean microbes.

Recommended for you

History books spark latest Texas classroom battle

18 hours ago

As Texas mulls new history textbooks for its 5-plus million public school students, some academics are decrying lessons they say exaggerate the influence of Christian values on America's Founding Fathers.

Flatow, 'Science Friday' settle claims over grant

18 hours ago

Federal prosecutors say radio host Ira Flatow and his "Science Friday" show that airs on many National Public Radio stations have settled civil claims that they misused money from a nearly $1 million federal ...

User comments : 0