Measuring twice, cutting once: Integrating sustainability into transportation planning

Tailoring and transportation share at least one thing in common — the better the planning, the better the product.

When tailors measure cloth twice before cutting, they’re maximizing efficiency and minimizing waste by first calculating carefully. In the transportation planning arena, that’s what sustainability is all about.

“Sustainable transportation” means different things to different people. In its recent project for the Texas Department of Transportation (TxDOT), the Texas Transportation Institute (TTI) defined it as “the provision of safe, effective and efficient access and mobility into the future while considering economic, social and environmental needs.” These needs are often called the “three pillars” of sustainability.

By measuring and applying these principles, a more sustainable — or safer, more effective — transportation system can be established. It’s easy enough to dream of sustainability, but without specific performance measures, it’s much more difficult to quantify and implement its principles.

“The three pillars are tied together by many cross-cutting issues, including how they affect and are affected by the development of our transportation system,” explains Joe Zietsman, director of TTI’s Center for Air Quality Studies. “What we’ve done is to figure out how we can measure these pillars of sustainability using data that’s already available.”

Zietsman’s team used TxDOT’s own strategic goals as a framework for defining how the pillars interact. With these goals in mind, the team developed sustainability objectives, created 13 sustainable transportation performance measures and a methodology for benchmarking them, and derived a method for combining those measures in one index for comparative purposes. This whole process was coded into a user-friendly Microsoft Excel®-based calculator.

Since the performance measures and their underlying methodology are uniform, researchers can compare different corridors and different sections of the same corridor in terms of their relative sustainability. A comparison can also be made over time between baseline and future conditions. This output can then be used by TxDOT to enhance the relative sustainability of their transportation corridor projects while ensuring the efficacy of their strategic goals.

“The 13 measures can help TxDOT see a more realistic portrait of the transportation system by simultaneously considering all three dimensions of sustainable transportation,” says Zietsman.

Researchers refined the methodology by evaluating case studies involving transportation corridors in San Antonio, Houston and Amarillo. That field work proved the flexibility and effectiveness of TTI’s approach in rural, urban and suburban environments.

Bill Knowles, TxDOT’s project coordinator, notes, “TTI’s research on this project provided a valuable planning method that is both practical and easy to use. The project findings are now being rolled out as an implementation project through a series of workshops in Texas’ largest metropolitan areas.”

As the United States looks to improve its transportation infrastructure, proactive planning tools like these will prove vital to getting the most from its transportation dollar.