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  3. Conventional traffic engineering assumes that given no increase in vehicles, more roads mean less congestion. So when planners i

Conventional traffic engineering assumes that given no increase in vehicles, more roads mean less congestion. So when planners i

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问题    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. It was like an inverse of Braess’s paradox.
   Mathematician Dietrich Braess of Ruhr University Bochum in Germany 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 enough attention 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. "Selfish drivers can be led to a better solution if you remove some of the network links, in part because closing roads makes it more difficult for individual drivers to choose the best (and most selfish) route."
By mentioning a commute in Paragraph 5, the author intends to______.
选项 A、suggest that congestion always take place in this route
B、prove that selfish driving does cause low efficiency
C、state that the work of Michael Gastner is worth reading
D、advocate that Nash equilibrium is more efficient than others
答案B
解析 此题为细节分析题。根据题干提示，定位答案位置。第五段第二句指出：研究人员分析了从哈佛广场到波士顿市民花园的开车族，发现自私驾驶的成本相当高昂；司机自私驾驶比在“社会最优”条件下驾驶通常要多花30％的时间，也就证明了自私驾驶确实造成低效率，因此B选项为正确答案。
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考研英语一

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