Agglomeration, all it really means is more people in the same place. As more people collect in a city center, more jobs cluster there too, boosting both wages and economic productivity over time. And the key to it all, may be public transportation. This thought is putforth by Daniel Chatman, Planning Scholar, University of California. He along with a fellow planner Robert, use concrete numbers to make the case that transit produces agglomeration. They report that this hidden economic value of transit could be worth anywhere from $1.5 million to $1.8 billion a year, depending on the size of the city. And the bigger the city, they find, the bigger the agglomeration benefit of expanding transit.
Studying agglomeration has been difficult since so many variables in play — from job density to population growth to transit development. So Chatman and Robert ran a number of statistical models that took into account all these factors, as well as economic productivity measures like average wage, for more than 300 metropolitan areas across the United States.Those that did revealed a pretty clear line from transit expansion to economic growth via agglomeration.
Every time a metro area added about 4 seats to rails and buses per 1,000 residents, the central city ended up with 320 more employees per square mile — an increase of 19 percent. Adding 85 rail miles delivered a 7 percent increase. A 10 percent expansion in transit service produced a wage increase between $53 and $194 per worker per year in the city center. The gross metropolitan product rose between 1 and 2 percent, too.
On average, across all the metro areas in the study, expanding transit service produced an economic benefit via agglomeration of roughly $45 million a year — with that figure ranging between $1.5 million and $1.8 billion based on the size of the city. Big cities stand to benefit more simply because they have more people sharing the transit infrastructure. They also tend to have more of the traffic that cripples agglomeration in the absence of transit. If the findings do hold true, they mean that cities and transit agencies are underestimating the true benefits of public transportation. This report brings another dimension on the need for public transportation.
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