SPRING 2011 -- ITS Ph.D. student Eric Gonzales received the Gordon F. Newell Award for Excellence in Transportation Science at a ceremony in the Transportation Library on March 11.
As the late Gordon Newell’s wife, Barbara, looked on, Assistant Professor Joan Walker presented the award for the first time since 2006 and only the fifth time since the award was established in 2001.
“The bar for this award is extremely high,” explained Walker. “With this award we are honoring the memory of Gordon Newell, a giant in our field. We’re also honoring a giant-in-training,” she said, praising the quality of Gonzales’ research and writing, his contribution to the development of a class in public transit, as well as teaching excellence.
Barbara Newell established the award following the death of her husband whose theories on traffic flow have become milestones that continue to shape the field.
Gonzales, who will receive his doctorate this spring, has written his dissertation on how to determine the most efficient and cost effective way to allocate space for various types of transport in cities.
Growing up near Denver, Colorado but spending summers with relatives in Stockholm, Sweden sparked Gonzales’ interest in cities and transportation, demand and road space.
“As a child visiting Stockholm, it struck me that these two cities have almost the same population—they’re both regional centers of industry and government—but they look really, really different, and the way we get around them is very different. So this relationship between how cities are built and how cities are served by transportation is what I really wanted to understand.”
All cities are different and there’s no one answer for every city, he explains. Obviously a solution for Berkeley would not look like a solution for New York City.
“But what interested me was finding a way to look at how a city is structured and to predict how the costs of traffic and or transit systems will respond to growing demand.”
In his most recent work, Gonzales did just that. He developed a systematic way to examine different types of cities, one that is also consistent with the realistic physics of traffic, to determine a system optimal transportation plan, which minimizes the social costs of providing mobility.
With a simple graph, Gonzales charts road space on a vertical axis and demand on a horizontal axis. Any city can be represented this way, he explains, from Berkeley to Hong Kong to Nairobi. Then he scales the two axes to reflect an individual city’s parameters: population, travel costs in terms of travel time, monetary resources and other costs, such as environmental impacts.
“I can describe any city by its demand and its road space, and then I can systematically show all the optimal solutions on this one graph,” he said.
Looking at the graph, Gonzales knows that cities that fall in the upper left quadrant where demand is low and roads are plentiful are served more cost-effectively when everybody drives cars. Those on the right quadrant where demand is high are more cost-effective when everybody rides transit.
But most cities are not so black and white. As they grow and become denser, demand increases. In many cities there is not enough road space for everyone to drive, but not enough demand to make transit cost-competitive.
“Now there are some situations where you want to mix the modes and other situations there should only be transit,” says Gonzales.
He points to a slender triangle on his graph.
“So this triangle is where interesting things happen. In some cases it’s best to mix modes, in some cases its best to push everybody onto transit.”
The problem with mixing modes, is that cities find themselves running a small transit service, which is a costly way to provide trips not only in terms of buying buses, but in terms of time: When a transit service is small, wait times and travel times for passengers using it are long.
“These small transit systems generally provide slow service, and people will not choose it without some incentive—which is why we end up throwing a lot of money into these kinds of services.”
In some cities only a minimal transit service should be provided, and cars and transit can share the streets. Other cities should invest heavily in comprehensive transit service and push everyone to use it, as London and Copenhagen have done. To some extent, the optimal solution depends on how wealthy a city is, as well as characteristics of its population and travel demand.
Choosing not to provide enough transit service or to subsidize it sufficiently leads to congestion that makes everyone worse off, he explains. The road space in a city needs to be well managed and modes need to be correctly priced.
Gonzales believes his system allows planners to know when they’ve reached a tipping point—the point at which the cost of providing minimal transit service is greater than going all out and investing in a transit system intended to serve everyone.
“Really, the usefulness of this work is about planning for the future, so that when we plan our cities and transportation systems, we plan for something we can physically achieve and be informed about how it’s going to work and how much it will cost us.”
To use a very broad example, Gonzales says, “there’s nothing wrong with saying you want to live in a city where everybody has an individual home with a picket fence. But it’s reasonable to presume that will not be a city with an extensive transit system.”