Removing Roads and Traffic Lights Speeds Urban Travel

[one...two...tree 2,762]

Urban travel is slow and inefficient, in part because drivers act in self-interested ways

By Linda Baker

Conventional traffic engineering assumes that given no increase in vehicles, more roads mean less congestion. So when planners in Seoul tore down a six-lane highway a few years ago and replaced it with a five-mile-long park, many transportation professionals were surprised to learn that the city's traffic flow had actually improved, instead of worsening. "People were freaking out," recalls Anna Nagurney, a researcher at the University of Massachusetts Amherst, who studies computer and transportation networks. "It was like an inverse of Braess's paradox."

The brainchild of mathematician Dietrich Braess of Ruhr University Bochum in Germany, the eponymous paradox unfolds as an abstraction: it states that in a network in which all the moving entities rationally seek the most efficient route, adding extra capacity can actually reduce the network's overall efficiency. The Seoul project inverts this dynamic: closing a highway—that is, reducing network capacity—improves the system's effectiveness.

Although Braess's paradox was first identified in the 1960s and is rooted in 1920s economic theory, the concept never gained traction in the automobile-oriented U.S. But in the 21st century, economic and environmental problems are bringing new scrutiny to the idea that limiting spaces for cars may move more people more efficiently. A key to this counterintuitive approach to traffic design lies in manipulating the inherent self-interest of all drivers.

A case in point is "The Price of Anarchy in Transportation Networks," published last September in Physical Review Letters by Michael Gastner, a computer scientist at the Santa Fe Institute, and his colleagues. Using hypothetical and real-world road networks, they explain that drivers seeking the shortest route to a given destination eventually reach what is known as the Nash equilibrium, in which no single driver can do any better by changing his or her strategy unilaterally. The problem is that the Nash equilibrium is less efficient than the equilibrium reached when drivers act unselfishly—that is, when they coordinate their movements to benefit the entire group.

The "price of anarchy" is a measure of the inefficiency caused by selfish drivers. Analyzing a commute from Harvard Square to Boston Common, the researchers found that the price can be high—selfish drivers typically waste 30 percent more time than they would under "socially optimal" conditions.

The solution hinges on Braess's paradox, Gastner says. "Because selfish drivers optimize a wrong function, they can be led to a better solution if you remove some of the network links," he explains. Why? In part because closing roads makes it more difficult for individual drivers to choose the best (and most selfish) route. In the Boston example, Gastner's team found that six possible road closures, including parts of Charles and Main streets, would reduce the delay under the selfish-driving scenario. (The street closures would not slow drivers if they were behaving unselfishly.)

Another kind of anarchy could actually speed travel as well—namely, a counterintuitive traffic design strategy known as shared streets. The practice encourages driver anarchy by removing traffic lights, street markings, and boundaries between the street and sidewalk. Studies conducted in northern Europe, where shared streets are common, point to improved safety and traffic flow.

The idea is that the absence of traffic regulation forces drivers to take more responsibility for their actions. "The more uncomfortable the driver feels, the more he is forced to make eye contact on the street with pedestrians, other drivers and to intuitively go slower," explains Chris Conway, a city engineer with Montgomery, Ala. Last April the city converted a signalized downtown intersection into a European-style cobblestone plaza shared by cars, bikes and pedestrians—one of a handful of such projects that are springing up around the country.

Although encouraging vehicular chaos seems at odds with the ideas presented in the price of anarchy study, both strategies downplay the role of the individual driver in favor of improved outcomes for everyone. They also suggest a larger transportation niche for bicycles and pedestrians. As the Obama administration prepares to invest in the biggest public works project since the construction of the interstate highway system, the notion that fewer, more inclusive roads yield better results is especially timely.

Faster Streets with Less Parking

New strategies in parking management could also improve urban traffic flow, remarks Patrick Siegman, a principal with Nelson/Nygaard Consulting Associates in San Francisco, a transportation-planning firm. In a misguided effort to reduce congestion, planners in the 1950s required developers to provide a minimum number of free parking spaces—a strategy that "completely ignored" basic economics, Siegman says, referring to how lower prices

increase demand.

Now limited urban space and concerns about global warming are inspiring city planners to eliminate these requirements. In San Francisco, for example, developers must restrict parking to a maximum of 7 percent of a building's square footage, a negligible amount. Although downtown employment has increased, traffic congestion is actually declining, Seigard says. With fewer free spaces to park, drivers seem to be switching modes, relying more on mass transit, cycling and just plain walking.

http://www.scientificamerican.com/article....ghts&page=2

[Pooky 3,795]

Roundabouts.

If I could get enough time on this thing, I'd pull up the study that suggests that the British model of the roundabout, whereby traffic already on the roundabout has priority to that joining (as opposed to the French system, which is #######-about-face), produces 40% fewer traffic accidents than traditional stop-sign and traffic light controlled junctions.

The wife, who tried driving in the UK (and did not get out of Sainsbury's car park in my car), did not believe it.

Somehow, I don't believe the people who did that study ever went to Basingstoke, aka City of Pointless Roundabouts.

Edited June 14, 2009 by Pooky

[Texanadian 10]

Linda Baker got it half right. Removing traffic lights speeds travel. Removing roads doesn't. You're only getting half of the story unfortunately.

Here's how it works in the real world with highways.....The highways get jammed. People start to take different routes, different entry/exit points, side streets, feeder roads, or if possible different highways. Others change their work day. Instead of 8-5 or 9-6, they work 6-3 or 7-4. The point being that people do whatever they can to avoid rush hour.

Then they build a new or bigger highway. So everybody switches back to their old ways. The normal work time. The normal highway. Overtime the highway gets filled again and the paragraph above this one happens again.

Now in the early 1990's, California decided that it was going to stop building new highways. Their reasoning being "as soon as we build them, they fill up." Also for the above reasons noted. I haven't kept up with how they've been doing since then. But traffic in CA is notorious for being the worst in the nation.

Now traffic lights on the other hand continuously are a burden to motorists put in by moronic city councils. Areas that used to be a 10 mile commute with 3 traffic lights can often have 9 or 10 traffic lights now. The reason for the increased traffic light count is for "traffic calming." The idea that spreading out traffic is a better method than having everybody all bunched together......In reality, it's creating a log jam behind you and depending on where your car is, either nobody in front of you or a huge line in front. Driver patience declines when faced with multiple stop lights or unnecessary stop signs. It's also a huge waste of gas and time.

The English roundabouts work great. We have them in Houston. I didn't know that the French roundabouts had different rules.

Where Texas really shines is the "Texas turnarounds." They should be mandatory in every state. They allow you to make a U-turn from the one side of the highway to the other without using any traffic lights. Typically you drive under the highway. So if you're on the highway and you pass your exit. You simply get off at the next exit, make the U-turn under the highway and head back to where you were going. While you're under the highway, oncoming traffic will be passing your passenger door. (there is a barrier, so no head on collision)

Lastly, with the safety standards and vehicle safety systems (airbags, high seat belt use, ABS etc), we need some faster speed limits.

http://en.wikipedia.org/wiki/Speed_limits_...e_United_States

[scandal 951]

Actually, to me the main lesson from these sorts of studies is that if you let individuals maximize their own personal utility functions, you won't necessarily get an optimal result for the society at large. It's a classic situation in which you need a group dynamic to coerce individual behaviors in a better direction.

A similar situation unfolds with antibiotics. Individuals who get sick, or who have a sick child, rush out and demand that their doctors give them a scrip for an antibiotic. Nine times out of ten the antibiotic will do no good (since most routine infections are viral anyway). However by over prescribing antibiotics we have inadvertently created new generations of antibiotic-resistant bacteria. We'll soon be arriving at the point where we have no effective tools to fight massive bacterial epidemics and our fight against infectious disease will appear more like the 19th century than the mid-late 20th century. If instead of allowing individuals to insist on antibiotics (which they do in an effort to promote their individual health), we regulated the distribution of these important medicines with an eye to what is really best for all of us as a society - well, we'd all be better off.

[one...two...tree 2,762]

Actually, to me the main lesson from these sorts of studies is that if you let individuals maximize their own personal utility functions, you won't necessarily get an optimal result for the society at large. It's a classic situation in which you need a group dynamic to coerce individual behaviors in a better direction.

A similar situation unfolds with antibiotics. Individuals who get sick, or who have a sick child, rush out and demand that their doctors give them a scrip for an antibiotic. Nine times out of ten the antibiotic will do no good (since most routine infections are viral anyway). However by over prescribing antibiotics we have inadvertently created new generations of antibiotic-resistant bacteria. We'll soon be arriving at the point where we have no effective tools to fight massive bacterial epidemics and our fight against infectious disease will appear more like the 19th century than the mid-late 20th century. If instead of allowing individuals to insist on antibiotics (which they do in an effort to promote their individual health), we regulated the distribution of these important medicines with an eye to what is really best for all of us as a society - well, we'd all be better off.

Well said.

[Saddle Bronc 124]

Roundabouts.

If I could get enough time on this thing, I'd pull up the study that suggests that the British model of the roundabout, whereby traffic already on the roundabout has priority to that joining (as opposed to the French system, which is #######-about-face), produces 40% fewer traffic accidents than traditional stop-sign and traffic light controlled junctions.

The wife, who tried driving in the UK (and did not get out of Sainsbury's car park in my car), did not believe it.

Somehow, I don't believe the people who did that study ever went to Basingstoke, aka City of Pointless Roundabouts.

Are you saying that France (and Basingstoke) coincidentally base their roundabouts on Indian ones (ironically many of these were installed by British prior to Partition)?

(re Indian roundabouts--no different from intersections and straightaways, traffic always displays absurd-sounding "stable level of chaos)

Edited June 15, 2009 by CherryXS

[mawilson 2,133]

Roundabouts.

If I could get enough time on this thing, I'd pull up the study that suggests that the British model of the roundabout, whereby traffic already on the roundabout has priority to that joining (as opposed to the French system, which is #######-about-face), produces 40% fewer traffic accidents than traditional stop-sign and traffic light controlled junctions.

That doesn't even make any sense - roundabouts *are* accidents waiting to happen.

[mawilson 2,133]

Actually, to me the main lesson from these sorts of studies is that if you let individuals maximize their own personal utility functions, you won't necessarily get an optimal result for the society at large. It's a classic situation in which you need a group dynamic to coerce individual behaviors in a better direction.

America has always been about individualism and self-reliance, not what's "good for society".

"We were challenged [at the end of World War I] with a peace-time choice between the American system of rugged individualism and a European philosophy of diametrically opposed doctrines — doctrines of paternalism and state socialism."

-- Herbert Hoover (1928)

[Saddle Bronc 124]

Roundabouts.

If I could get enough time on this thing, I'd pull up the study that suggests that the British model of the roundabout, whereby traffic already on the roundabout has priority to that joining (as opposed to the French system, which is #######-about-face), produces 40% fewer traffic accidents than traditional stop-sign and traffic light controlled junctions.

That doesn't even make any sense - roundabouts *are* accidents waiting to happen.

Or (in specific case of Indian ones) accidents in-process.

[Scott & Lai 12]

Actually, to me the main lesson from these sorts of studies is that if you let individuals maximize their own personal utility functions, you won't necessarily get an optimal result for the society at large. It's a classic situation in which you need a group dynamic to coerce individual behaviors in a better direction.

America has always been about individualism and self-reliance, not what's "good for society".

"We were challenged [at the end of World War I] with a peace-time choice between the American system of rugged individualism and a European philosophy of diametrically opposed doctrines — doctrines of paternalism and state socialism."

-- Herbert Hoover (1928)

[Peikko 1,575]

Its a shame America moved away from pioneering then because individualism and self-reliance are simply phrases thrown out willy nilly but actually signify nothing in relation to modern America.

[mawilson 2,133]

Its a shame America moved away from pioneering then because individualism and self-reliance are simply phrases thrown out willy nilly but actually signify nothing in relation to modern America.

You really think so, do you? Must be true then.

[Peikko 1,575]

For political purposes, yes I do.

There is nothing wrong with self reliance and individualism in the proper context, but if one is suggesting by using these phrases that the individual can succeed without help from greater society, then that's delusional - unless you have a predilection for living in the middle of no where with no running water, no electricity and no waste disposal system and no access to modern telecommunication and media systems.

[mawilson 2,133]

For political purposes, yes I do.

There is nothing wrong with self reliance and individualism in the proper context, but if one is suggesting by using these phrases that the individual can succeed without help from greater society, then that's delusional - unless you have a predilection for living in the middle of no where with no running water, no electricity and no waste disposal system and no access to modern telecommunication and media systems.

You can certainly live off the grid without any help from "society" and many people, in fact, do.

They generate their own electricity, pump their own water and dispose of their own garbage.

Some even call it "the American dream".

[Peikko 1,575]

I didn't say it could not be done, I said that if it is used in a political context it's generally garbage because that is not what most people want these days.