Transportation agencies and planning organizations often stress the importance of accessibility—connecting people to jobs and services—but formal accessibility analysis has traditionally fallen more upon academic researchers and advanced modelers. Meanwhile, our historical reliance on metrics like traffic speed, transit reliability and sidewalk coverage as proxy measures for accessibility-related outcomes has led to piecemeal implementation and unintended consequences like increased sprawl and rising transportation emissions.
Measuring Accessibility: Guidance for Practitioners
Our new guide, Measuring Accessibility, is tailor-made for transportation and land use practitioners getting started in accessibility analysis.
Included in the Guide
The guide employs some of the most common techniques in emerging practices to produce meaningful metrics while relying on data that is either free or inexpensive and analytical methods that do not require extensive training. Sections include:
Transportation data should reflect where and how easily people can travel. This includes roads and traffic speeds, along with bicycle, pedestrian and transit networks. Some agencies keep useful data on hand, but some may need to rely on other free and commercial data sources outlined in this guide.
Land Use Data
Measuring accessibility means knowing where people live and where there are opportunities to work, shop and meet other daily needs. Census data can be packaged with other robust land use data to evaluate work and non-work accessibility.
Methods and Tools
With the right data, transportation agencies can leverage a range of analytical tools and user friendly platforms to quickly produce local and regional accessibility metrics. This guide outlines technical approaches, as well as more practical considerations to apply the metrics in decision-making.
This guide was informed by our work and partnership with transportation agencies across the U.S and supported by NUMO. Whether they are just starting their accessibility work or are advancing the practice, we continue to work with these partners, as well as to produce updated guidance and standards.
SSTI’s team of researchers, analysts and policy experts leverage a growing number of available tools and platforms—including CUBE Access (formerly Sugar Access), Conveyal, TransCAD, Network Analyst, and existing travel demand models—to conduct meaningful accessibility analyses and incorporate them into practical decision-making applications like benchmarking and project prioritization.
We work with state DOTs, metropolitan planning organizations (MPOs), local governments, and experts in the field, building on decades of relevant research, to help set up analytic platforms, integrate the right data sources, create workflows, and establish standards to guide the emerging field of accessibility analysis. Our research also helps tie accessibility to other important outcomes like vehicle miles traveled (VMT), mode choice decisions, and transportation costs.
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Virginia’s Smart Scale project prioritization process evaluates all potential transportation investments using multimodal accessibility analysis. SSTI has supported the development and advancement of this approach and helped the Virginia DOT implement a new land use metric based on walking accessibility to non-work destinations.
SSTI and Smart Growth America helped the Hawaii DOT pilot the Smart Transportation Rank Choice (SmartTRAC) program to better align transportation investments with priorities around safety, preservation, accessibility, traffic management, and environmental protection. This involved assessing the mode shift potential of bike and pedestrian projects using accessibility analysis.
The Washington State DOT launched a multimodal accessibility program in 2019 with technical support and research assistance from SSTI and Smart Growth America. Their program sets a new framework for thinking about transportation system performance, identifying transportation gaps, and evaluating outcomes like environmental justice, health, and travel options.
Building on the success of its ongoing pooled-fund study, the Minnesota DOT enlisted technical support from SSTI to move from theory to practice. This work involves setting up a new analytic platform and conducting case studies with a number of local partners to assess impacts ranging from highway investments to school siting decisions.
As a pilot project, SSTI evaluated multiple proposed transportation projects in the Boston area for accessibility benefits. We then demonstrated how the findings could be used to develop a cost-benefit-based STIP or TIP, as well as to maximize the benefits of projects as they are developed.
SSTI led research sponsored by the Utah DOT to better understand how accessibility metrics could apply in multimodal project prioritization, as mandated by SB136 in 2018. Our team also worked with the Wasatch Front Regional Council to better incorporate Access to Opportunities into long-range planning and to help coordinate efforts across agencies.
SSTI worked with the Sacramento Area Council of Governments (SACOG) and other local partners to measure transit accessibility across the region and identify opportunities to improve first- and last-mile connections, leveraging other big data sources to better understand trip-making patterns near transit stations and along rail corridors. Learn more about the project.