The young inventor envisages PaveGen systems being used to power off-grid appliances such as public lighting, illuminated street maps and advertising, and to be installed in areas of dense human traffic such as city centers, underground stations and school corridors.

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To address the crush, carriers are offloading data traffic from dense urban areas onto Wi-Fi networks, while also seeking out more spectrum.

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The popularity of the City's scheme suggests that the advantages of traffic restriction in dense urban areas may have been underestimated in the past.

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Chicago came in second, due largely to its dense urban population, crippling traffic and the fact that motorists in the Windy City are subjected to fuel costs that are 30 percent higher than the U.S. average.

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Small, shared vehicles are easy to park and maneuver in dense urban centers, and cut down on traffic and fuel consumption.

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The dense fog has also been causing travel chaos, with air and rail traffic severely disrupted.

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Worldcom was one of the first carriers to deploy a newfangled technology called "dense wavelength division multiplexing" (FORBES, Oct. 7, 1997) that greatly increases the amount of traffic an existing fiber-optic cable can carry.

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