Editorial: Spread-City Everywhere

Melvin M. Webber

It happened first in America, but by now spread-city is becoming the standard urban form worldwide. Ease of economic transaction and social interaction among distant partners has assured success for the new-style city, even though it diverges so far from city forms of the past. First there was that historically extensive series of technological developments that, cumulatively, reduced the friction of geographic space: the astrolabe and compass, sailing ships, canals, telegraphs, railroads, paved roads, telephones, radios, automobiles, airplanes, the Internet. All of them connected people located in different places and, increasingly, permitted them to behave as though they were in the same place. Each technological development contributed to parallel institutional developments extending to ever-more-distant locales.

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2017-05-30T22:32:31+00:00Categories: ACCESS 24, Spring 2004|Tags: , |

On The Back Of The Bus

Theodore E. Cohn

You'll no doubt be surprised to read that transit buses get rear-ended more often than passenger cars do. You’re surprised, I suspect, because buses are so large and obvious. Who could fail to see that bulky bus? Who could fail to know it moves slowly and stops often? These collisions are a tremendous waste of resources. Crashes injure both bus patrons and passengers in other vehicles, damage expensive equipment, cause delays and service disruptions, worsen traffic congestion, lessen acceptance of transit as a travel choice, and they’re expensive. A 1997 estimate found that each crash cost $54,000. Plus, we find, these crashes are largely preventable.

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Complications At Off-Ramps

Michael Cassidy

You're driving along the freeway when suddenly everything slows down. A crash? A sudden overload of cars joining the freeway from on-ramps up ahead? Maybe. Sometimes the cause never reveals itself to you—inexplicably, everything just starts moving again. If this happens every day in the same spot, you may develop a theory or two as to why it happens. Would it occur to you that the congestion might be caused not by too many cars getting on the freeway but by too many cars trying to get off? For decades, traffic engineers have been managing freeway congestion by using meters to restrict the rates that vehicles enter the freeway from on-ramps. A metering scheme can often keep cars moving faster on the freeway, and sometimes can even reduce traveler delay systemwide. Realizing these benefits requires metering that is suitably designed, but traffic engineers disagree about what constitutes a suitably designed plan.

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Clean Diesel: Overcoming Noxious Fumes

Christie-Joy Brodrick, Daniel Sperling, and Harry A. Dwyer

What is the truth about diesel engines? Are they inherently dirty? Do they belch clouds of black soot? Are they unsuited to cars, as evidenced by 1980s class-action suits against GM’s diesel “lemons?” Do they make an unnecessary racket when idling and accelerating? Are their emissions toxic and a threat to human health? Many ask, in this age of ultra-clean transport, why do we still have diesel engines? The governor of Tokyo and air quality regulators in southern California have both launched campaigns to ban them. But there’s another side to the story of diesel engines. European regulators assert they are an answer to climate-change threats. Many automotive companies claim that new diesel engines are dramatically improved and as clean and quiet as gasoline engines. And freight companies rely almost exclusively on diesel engines for their trucks because they are durable and efficient. Indeed, diesel engines continue to increase their market share worldwide, now accounting for about forty percent of all roadway fuel consumed.

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R&D Partnership for the Next Cars

Daniel Sperling

In September 1993 President Bill Clinton and chief executive officers of Ford, Chrysler, and General Motors created the Partnership for a New Generation of Vehicles (PNGV). Their primary goal was to develop a vehicle with up to three times the fuel economy of midsize 1993 US cars (about eighty mpg) with no sacrifice in performance, size, cost, emissions, or safety. Billions of dollars were to be spent over ten years, split roughly fifty-fifty between government and industry. They planned to select the most promising technologies by 1997, to build a concept prototype by 2000, and to have a production prototype by 2004. The program has adhered to that schedule.

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2017-05-30T23:07:40+00:00Categories: ACCESS 18, Spring 2001|Tags: |

The Road Ahead: Managing Pavements

Samer Madanat

A new-laid stretch of pavement is not a finished product. Traffic pounds it; hot sun heats and expands it; water gets inside and washes away the soil beneath. Depending on these forces and the quality of its design and construction, a pavement will last only a limited time before it needs repair or replacement. Because there are so many factors involved, it’s not possible to just schedule a replacement in x number of years. The pavement has to be checked periodically for potholes and cracks and ruts. Visual and manual inspections can be slow, hazardous, and fraught with uncertainty. But that’s the way it’s always been done.

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2017-05-31T21:27:16+00:00Categories: ACCESS 17, Fall 2000|Tags: |

What If Cars Could Drive Themselves?

Steven E. Shladover

Even when cars were still young, futurists began thinking about vehicles that could drive themselves, without human help. Perhaps the best known of these conjectures was the General Motors Futurama, the hit of the 1939 New York World’s Fair. During the following decades interest in automated vehicles rose and fell several times. Now, at the start of the new century, it’s worth taking a fresh look at this concept and asking how automation might change transportation and the quality of our lives.

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2017-05-31T21:27:43+00:00Categories: ACCESS 16, Spring 2000|Tags: |

Power from the Fuel Cell

Timothy Lipman

Automobiles are often criticized for consuming so much petroleum. While much has been done in the past twenty years to make vehicles pollute less, the growing popularity of larger vehicles is making vehicles consume more energy. However, emerging technologies suggest that new generations of vehicles can be built that will be much more efficient than those on the roads today. Furthermore, the prospect of future vehicles incorporating electric drive systems means they may be able to integrate with the electricity grid in a novel way: they may be able to supply electricity to the grid, thereby eliminating the need to build new power plants in some areas.

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2017-05-31T21:27:54+00:00Categories: ACCESS 16, Spring 2000|Tags: |

An Eye on the Fast Lane: Making Freeways Work

Pravin Varaiya

Before leaving for work you can check the weather from the newspaper, radio, or TV report. You can just look at the sky and make your own guess. But you can’t determine much about current traffic conditions. TV and radio traffic reports provide only a summary (“traffic is running smoothly this morning”) and spotty coverage of incidents (“an accident in the second lane has been cleared”). If you are unexpectedly stalled in traffic, your frustration and anxiety mount. You don’t know how long you’ll be stuck or whether you should use your cell phone to cancel your appointment.

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Requiem for Potholes

Carl Monismith

On the surface, pavement must seem beneath consideration. No reason to think about it—you just drive on it, park on it, watch out of the corner of your eye to make sure your car is following the lines painted on it. Until, that is, until you hit a pothole. Then you’re suddenly aware of the pavement, or at least of its flaws. You may swerve, you may curse, you may write a letter to the mayor—a pothole can have that kind of power.

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