By David Zipper
With commuters grounded and passenger numbers likely to remain low in U.S. cities, public transportation leaders should focus on a different metric for usefulness: transit access.
Of all the information that U.S. public transit agencies track, none is more important to them than ridership — the number of people boarding its buses, trains and subway cars. Agency executives monitor their ridership data as closely as a CEO watching her company’s stock price. “We’ve always used ridership as our main metric,” says M.J. Maynard, CEO of RTC Southern Nevada in Las Vegas. “We’re constantly drawing comparisons with each other and bragging when our numbers are bigger.”
Dollars are at stake in addition to pride; ridership partly determines the amount of federal funding allocated to each system. The national transit industry scrutinizes passenger numbers too, celebrating a national uptick and bemoaning a downturn.
But the coronavirus pandemic has shown that ridership is an imperfect measure of transit’s importance. With offices shuttered and agencies themselves advising passengers to avoid all but essential trips, passenger counts collapsed by as much as 90% on rail service in Washington, D.C. and San Francisco. Ridership on buses has slumped as well. And these numbers are unlikely to snap back quickly to pre-Covid levels, as work-from-home habits forged during the pandemic stand to leave lasting marks on commuting patterns in major cities.
Few people would argue that these systems’ societal value has fallen as steeply as their ridership. On the contrary, the pandemic has reminded us that cities cease to function if public transportation is unavailable. You might be able to drive to a hospital or grocery store, but that won’t do you much good if transit-reliant workers can’t get there to staff it.
The pandemic is an extreme example of an external force that pushes transit ridership up or down for reasons no agency can control. Others include economic factors, socioeconomic change, land use patterns and the price of other transportation modes. For instance, an agency could add bus frequency but still see ridership fall because cheap gas nudged riders toward driving. Or an agency could do nothing differently at all, and then watch ridership grow during a prolonged period of unusually bad weather. In neither case do transit leaders deserve credit or blame for changes in passenger counts.
Given ridership’s limitations as a measure of success, it’s worth asking if an alternative metric could provide a clearer picture of transit’s value — and also help agencies make good service decisions. Happily, there is one — “access,” which quantifies a transit system’s ability to help people reach the places they want to go.
The basic method of calculating access is intuitive: Pick a particular neighborhood, and then determine the time it would take for a person living there to use transit to reach jobs dispersed throughout the region (people take many other kinds of trips, but commute data is most readily available). Transit planners can then aggregate the data to calculate an overall regional measure of access, or they can create one for a subset of the population (say, minorities or low-income residents). Agencies are then able to use these calculations when designing a systemwide service map or when making a narrower decision, like choosing whether to open a new route or add frequency to an existing one. An agency can continue to monitor the accessibility of its service, defined as the share of jobs reachable for a given population within a given trip time, such as 60 minutes door-to-door.