Bob CollinsThe University of Minnesota’s Accessibility Observatory this week released its study (pdf) ranking the 46th largest metro areas, calculating how many jobs a resident could get to during a morning commute by transit.
Eric Jaffe at City Lab calls it the “carless commute ranking to end all carless commute rankings.”
First, they capture the importance of transit frequency across an entire system. The rankings take into account accessibility at every minute between 7 and 9 in the morning. Systems that run a lot of buses and trains, therefore, perform better than those with inconsistent or infrequent service. In this way, the list captures the way most of us run our lives: Real-time transit updates aside, we leave for work when we’re ready to leave, not at an exact hour and minute.
Second, the comprehensive door-to-door approach also captures the importance of transit-oriented development and walkability. A 30-minute bus ride becomes an hour commute with a 15-minute walk on both ends. But it becomes a far more manageable 40-minute commute when homes and offices are located closer to transit stations. So two cities with the same service frequency can still vary considerably in terms of job access based on the type of density and land use that occurs at either end of the trip.
“Accessibility is the single most important measure in explaining the effectiveness of the urban transportation system,” David Levinson, University of Minnesota civil engineering professor and principal investigator on the project, said in a news release.
In 10 minutes, a Twin Cities-area resident could reach 589 jobs by transit, the report said. With a half-hour transit commute, that number jumps to more than 17,000.
Overall, using a weighted average, the Twin Cities area ranks #13, which is surprisingly good, at least for a blogger who can’t get a bus from Woodbury after 7:50 a.m.
The report appears to stress that there’s more to transit than just speed of service; there’s also frequency of service that expands accessibility to transit. That is: How well does transit connect people with what they need to reach?
Not all jobs are the same. Some jobs are higher paying, some are lower skilled, and they exist in a variety of industries. Given sufficient data, one could differentiate accessibility by breaking down jobs by type and get different results. Accessibility to non-work locations (shopping, health care, education, etc.) is also important. Regardless of trip purpose, people who experience higher accessibility tend to travel shorter distances because origins and destinations are closer together.
But accessibility to jobs is not the only thing that people care about. If it were, cities would be situated on a minimum amount of space so people could live immediately adjacent to their jobs, or everyone would work from home. Measuring (and then valuing) accessibility to other opportunities and considering the trade-off between accessibility and living space are central problems of urban economics, regional science, and transportation and land-use planning. While being more accessible is generally better, there are costs as well as benefits associated with accessibility. If land is more valuable, its price is higher, and purchasers can afford less. Streets in places with more activities are inherently more crowded, and trips are less peaceful.
Accessibility is a function of both transportation and land-use decisions, which has important policy implications. There are two broad avenues to increasing accessibility: improving transportation systems and altering land-use patterns. Neither of these things can be easily shifted overnight, but over time they do change—both through direct plans and action and through market forces.
It is important to recognize that aggregate metrics such as these are also affected simply by the size of the areas being studied. For example, residents of central Minneapolis enjoy greater accessibility than
those of central Milwaukee, but the expansive Minneapolis–Saint Paul metropolitan area includes far more suburban and exurban areas (with little or no transit service) than does the Milwaukee area.
