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Study Measures U.S. Cities on Transportation, Climate Impact

The 2020 U.S. Transportation Climate Impact Index by StreetLight Data ranked the top 100 metro regions around key transportation metrics and for their contribution to greenhouse gases.

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Those cities taking steps to break away from suburban, car-oriented development and create opportunities to bike or use public transit more frequently are going to be the places poised to make the most headway in reducing greenhouse gas emissions.

A new report by the transportation analytics firm StreetLight Data ranked the 100 largest metro regions on six significant per capita categories to get a sense of how a region’s transportation system — a multi-layered network of highways, transit routes, bike lanes and even sidewalks — contributes to climate-warming greenhouse gases.

The 2020 U.S. Transportation Climate Impact Index ranked cities in several areas: transit, population density, vehicle miles traveled, bike commuting, pedestrian commuting and circuity, which analyzes the directness of a traveler’s route.

The New York City metro region ranked No.1 for its robust transit systems, relatively high housing density and the large number of workers commuting via walking or biking. New York was followed by the San Francisco region, which includes Oakland.

Madison, the small college city and capital of Wisconsin, ranked third, aided largely by scoring well in the vehicle miles traveled (VMT) category — an indication of few cars relative to other big-city regions, and less driving. Madison also ranked in the top 20 percent when examining bike commutes.

“On one hand, it’s a no-brainer that pedestrian and biking activity is good,” said Martin Morzynski, vice president of marketing at StreetLight Data.

“But, how much impact can I have as a city on my city’s carbon footprint by promoting bike lanes, versus rail, versus pedestrian activity?” he added, remarking on how the data gives a broad look at how a region’s overall transportation system is used, and can be modified to reduce greenhouse gases.

It should be no huge surprise that metro regions like Dallas and Phoenix — largely car-dependent — ranked poorly on the StreetLight Data climate impact index. In fact, Dallas ranks dead last in the vehicle miles traveled category, an indication of many workers traveling long distances in their own cars.

The purpose of the data in the report, derived largely from location-based data generated from smartphones, is intended to serve as high-level information for cities aiming to explore policy directions to reduce greenhouse gases.

“If I’m Madison, Wis., or Des Moines, [Iowa], I may not see the need to improve my pedestrian commuting because it’s just not a very dense city, but I might have a lot of potential to drive bike activity,” Morzynski explained. “If I can understand the relative importance to shifting the total needle, it’ll start to basically help me make choices about what do I focus on in the next 12 to 36 months to have impact.” 

Reducing car use, or at least single-occupancy trips, is the most obvious path to an improved climate index score. It was also the overall theme of the CoMotion LA conference in November, a multiday discussion in downtown Los Angeles dedicated to the societal benefits and overall urgency of transforming the transportation sector in the United States. And as cities explore the many ways to eliminate car trips from their transportation footprint, they should think creatively about the transportation networks and infrastructure they already have.

“Any move away from a kind of single-use urban design strategy is a good one,” said Christopher Hawthorne, chief design officer for the city of Los Angeles, as he encouraged multiple uses for parking lots, allowing them to transition into package or food delivery staging areas.

“We no longer have the luxury of giving over territory of the city to spaces that only have one use. And certainly a parking structure, or parking lot, is part of that,” said Hawthorne.

The Los Angeles metro area, which includes Long Beach and Anaheim in Orange County, ranks at No. 34 on the StreetLight climate impact index, with relatively strong scores in biking and transit use, but it loses ground when vehicle miles traveled are taken into account.

“We really have to lead with the more choices, more options available, rather than forcing people out of their cars,” said Lilly Shoup, senior director of policy and partnerships at Lyft, in her comments around a discussion to get Angelenos out of their cars.

The climate impact index, said Morzynski of StreetLight Data, is intended to be a starting point for cities, which may need more granular data to, say, understand where biking infrastructure should go to increase bike commuting.

“It allows you to understand tradeoffs between investments in different modes, to get them along the fastest, given what is commonly understood to be a pressing issue. We may not want to wait for a rail line to get built that’s going to take six years,” said Morzynski. “It’s a way to accelerate the discussion, and provide a tool for smaller communities that may not have the resources to make massive investments.”

Skip Descant writes about smart cities, the Internet of Things, transportation and other areas. He spent more than 12 years reporting for daily newspapers in Mississippi, Arkansas, Louisiana and California. He lives in downtown Yreka, Calif.