A photo of a DART light rail train in Dallas, Texas.
Despite a big expansion, the share of Dallas residents who rely on "sustainable transport" like the city's DART light rail system has remained stubbornly low. Tony Gutierrez/AP

Cities could get more people walking, biking, and riding transit, according to a new report, if they just know where to look for improvement.

Each year, the U.S. Census releases an update in “commuting mode shares” in its American Community Survey. This is an annual accounting of the share of people in every U.S. city who bike, walk, or ride public transit to their jobs, as well as drive. Mostly the latter: Nationally, about 75 percent of the country is sitting alone in their cars every morning. About 10 percent carpool, 5 percent ride transit, and the last 10 percent either walk, bike, or work from home.

If you peruse this data-dump every year, you’ll probably notice something: Despite the tireless efforts of transit planners, bike-lane boosters, and other actors in the mobility arena, the mode-share percentages don’t seem to budge much in the any given growing city as they add more people, despite massive investments in transit infrastructure. Take Dallas, Texas, for example: In 1996, that city opened the first stage of its light-rail network, which has since grown into the largest system in the U.S., at a total cost of something around $5 billion. But the share of commuters in the city who ride transit has remained below 6 percent since 1990.

This can be exquisitely frustrating as cities task transportation leaders with tackling some of the country’s most daunting challenges, from reducing climate change to alleviating economic inequality. But a new report and interactive tool from the Institute for Transportation & Development Policy wants to make the leap to a low-car future feel less enervating by breaking the numbers into smaller chunks. They’ve developed a suite of “indicators for sustainable mobility,” aimed at helping cities measure their transit systems for better outcomes by taking a closer look at where and how they reach jobs and people.

To do that, the report digs deeper in the 2015 ACS data to get a more complete picture of how cities can improve their share of sustainable transport—that’s public transportation plus walking, biking, scootering, and any other means of moving around that doesn’t involve a car. No matter if this category makes up the majority of commuters, as it does in New York City (66 percent) or the extreme minority (Nashville, 4 percent), there’s more to say about how it reaches people, housing, and jobs in any given city. (For a wider comparison, the report also looks at mode share in four Canadian cities and transit access in four cities in Mexico)

Oh, Canada: Vancouver, Toronto, and Montreal beat out Boston, Philadelphia, and Seattle on sustainable transport mode share. (ITDP)

The study breaks the data down into 12 different indicators to assess transportation options in 20 cities in the United States. It looks at factors such as how many people live or work within a 10 minute walk or bike to transit, and how many jobs they can reach within 60 and 30 minutes. The result is a more bite-sized and relatable look at where transit can improve, especially on the city-level interactive that lets you pick apart the data and compare with other cities.

“One of the things that we try to do with all of our indicators is make them actionable and easily communicated,” says Joe Chestnut, a research associate at ITDP. “You could very easily have weighted each of these individual indicators and come up with a score for each individual city.”

A weighted-index does not quite get at why only 30 percent of Seattleites took sustainable transportation in 2015 when 91 percent of its jobs are within 10 minutes of what the report considers “frequent service,” where any stop is serviced an average of 5 times an hour between 7 a.m. and 9 p.m. But there’s a mismatch in accessibility: Only 10 percent of Seattle residents were reachable within 60 minutes by walking, biking, or public transit. Even the city’s successful rapid-transit options only reach 7 percent of its population.

The result is a set of measures that can explain a lot more about what certain cities get right or wrong on transit, and what they can do to improve their lot. The key, the reports stresses, is getting a better balance between jobs, low-income households, and people in proximity to public transit.

Mode share is the result of a puzzle to match where jobs and people are. (ITDP).

In the chart above, you can see the power of density: Philadelphia and Boston benefit from compact city blocks, while Louisville and Charlotte suffer from sprawl. Transit networks in Denver and New Orleans reach plenty of jobs, but could improve by reaching more people; Memphis and Indianapolis, on the other hand, need more jobs located closer to frequent transit. (A spotlight report paired with the indicators gets further into the nitty-gritty for Dallas, Denver, and Nashville.)

Ultimately, the breakdown of the numbers demystifies the tradeoffs being made in service networks that say, a subway map or bus schedule cannot convey alone. It also underscores the importance of frequency, not just access. “If you’re doing well on accessibility indicators, but doing poorly on population near frequent transit, what that likely means is you have transit near people, but that transit must not be frequent,” says Chestnut. “If something leaves like once an hour, that’s not a great commuting option.”

But making progress on these indicators does not necessarily mean having to overhaul your public transit options or build new systems from scratch. Consider Minneapolis and its progress on biking. If you factor in improvements in bike infrastructure, the population living near frequent transit jumps 9 percent, rising from 64 to 73 percent. “We only included protected bike lanes as a way to travel by bike in the transportation network,” says Chestnut. “It goes to show that number of people who have access to frequent transit can be improved without having to put in vast sums of money.”

That access could improve even more as the city builds on its ambitious Minneapolis 2040 plan, a comprehensive effort to curb the influence of single-family zoning and add more housing density. “Minneapolis has been getting a lot of attention for land use and zoning recently, but the way they invested in bikes shows that protected infrastructure matters too. If people don't feel safe on their bikes, they’re not going to take them.”

When Minneapolis added protected bicycle infrastructure, like this bike-pedestrian bridge,is also boosted the number of city residents who could access transit networks. (Jim Mone/AP)

Another avenue where each city has room for improvement is with providing better transit service to people living in low-income households that earn less than $20,000 a year. Los Angeles may not reach as much large of a share of its total population with frequent transit in its car-centric sprawl, but where it does reach matters to a larger share of low-income households that rely on it compared to say, Atlanta. The indicators make that task appear not as difficult as you might think: Transit networks do reach where low-income people live; it is just that service needs to be more reliable.

“In almost every city, a larger share of low-income households were near frequent transit more than the share of the population as a whole,” says Chestnut. “But for low-skill jobs that pay less, those indicators are much worse than for getting to all jobs. In D.C., one fifth of all jobs are accessible within 60 minutes, but if you look at [jobs that don’t require a high-school diploma or college degree], it’s only 4 percent. A lot of that has to do with how poorly the Metro runs on the weekends. If people can’t easily get around, it makes their lives so much harder.”

While the report may not be wonky enough to make causational arguments or to engineer the granular day-to-day decisions that planners make, it could focus the conversations that regular residents have about how their transport network is performing, and exactly where it needs get better. “You need to have goals,” says Chestnut. “You need to have climate goals; you need to have mode goals. We wanted to do this because we could benchmark cities and find out if they’re doing better a few years later. If they do a bus redesign, are they going to do better on these indicators? Cities need to be measuring these things and they need to have targets to meet that people can understand.”

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