ACCESS 27, Fall 2005

Opinion: In Praise Of Diversity

Paul Craig

The car has massively transformed physical and cultural aspects of every advanced society. It has enriched our society enormously. It has also cost us heavily and become a victim of its own success. External factors play growing roles. It seems likely that gasoline prices will remain high and that supplies will remain uncertain. Global climate change is becoming serious. So, it’s time to move ahead—to develop transportation systems for the 21st Century. The devastation in New Orleans makes that unfortunate city a good place to start. It’s going to be rebuilt, and that should be done with a view to the next century, not the last.

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What We’ve Learned About Highway Congestion

Pravin Varaiya

There are 26,000 SENSORS buried under the pavements of California freeways. Every thirty seconds, those sensors send data to our computers here in Berkeley. The data tell us about the number of cars driving on that freeway and their speed at that time. We also collect, process, and store data about collisions and other incidents. This database, PeMS (Performance Monitoring System), is now by far the most comprehensive source of information about California highways. Today it stores four trillion bytes of information, which are available online at We’ve already learned quite a lot from all those data. For example, we’ve found the error in the old belief that an average speed of 40 to 45 mph maximizes traffic capacity; we now know for a fact that maximum capacity occurs at around 60 mph. And we’ve been surprised to discover that some HOV lanes may have the perverse effect of actually adding to congestion.

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The Transition To Hydrogen

Joan Ogden

Of all alternatives to gasoline fuels, hydrogen offers the greatest long-term potential to radically reduce many problems inherent in transportation fuel use. For example, hydrogen could enhance energy security and reduce dependence on imported oil, since it can be made from various primary energy sources, including natural gas, coal, biomass, and wastes, and from solar, wind, hydro, geothermal, and nuclear energy. Also, hydrogen vehicles have zero tailpipe emissions and are very efficient. If it is made from renewable sources, nuclear power, or fossil sources with carbon emissions captured and sequestered, hydrogen use on a global scale could produce nearly zero greenhouse gas emissions and greatly reduce emissions of air pollutants.

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2017-05-30T22:28:44+00:00Categories: ACCESS 27, Fall 2005|Tags: , |

Hydrogen Highways

Timothy Lipman

The state of California has for many years been at the vanguard of environmental and energy policies, creating strict standards that have afterwards been adopted by other states. Today is no different. Despite a severe budget crunch, California Governor Arnold Schwarzenegger has recommitted the state to a variety of clean energy goals, including deregulation and liberalization of electricity markets, increased energy efficiency in new and retrofit state buildings, and reductions in greenhouse gas emissions. The state has also outlined a major solar-power initiative and a Renewable Portfolio Standard that sets goals for producing electricity from renewable sources. And in pursuit of the elusive zero-emission vehicle — the ZEV — the governor has called for California to take a leading role in advancing the commercialization of hydrogen-powered vehicles with the “California Hydrogen Highway Network.”

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2017-05-30T22:28:54+00:00Categories: ACCESS 27, Fall 2005|Tags: , |

Progressive Transport And The Poor: Bogotá’s Bold Steps Forward

Robert Cervero

Bogotá, the Andean capital of Colombia and home to some seven million inhabitants, is widely recognized for having mounted one of the most sustainable urban transport programs anywhere. In 2000, the city began operating a high-speed, high-capacity bus system, called TransMilenio, building upon the experience of Curitiba, Brazil’s much-celebrated success with dedicated busways. Bogotá’s leaders went one step further, giving investment priority to pedestrians, followed by bicycle facilities, then public transit, and lastly cars (i.e., inversely to travel speeds).

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Innovations In Traffic Modeling

Frank S. Koppelman

The study of travel behavior attempts to understand why, when, where, how, and with whom people travel. It then tries to predict how they will travel in the future. Predictions depend on the design and operation of future transportation systems and on changes in population characteristics. Thus, they are useful tools when choosing among alternative designs for future transportation services and sizing facilities to meet future demands.

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