Accessibility is the ease with which travelers can reach valued destinations. Measures of accessibility provide important information to transportation agencies to improve the performance of the transportation system across all modes to better meet human needs. Sometimes the term “accessibility” is used in reference to the specific requirements under the Americans with Disability Act; however, transportation agencies frequently consider accessibility to be a broader concept that is applicable to all user groups and modes and that accounts for distance, travel time, and other costs of reaching valued destinations.
One motivation for using an accessibility measure is that it can provide a user-centric approach to compare tradeoffs between proposed investments, including across modes. Additionally, accessibility measures can be used to understand the distribution of user benefits and costs of specific transportation investments or to more closely link transportation decisions with land use development. Accessibility measures can also serve as performance measures to expand the goal areas included in performance-based planning and programming (PBPP) efforts beyond the federally required transportation performance measures.
The specific choice of an accessibility measure is driven by not only available data, but also by the decision-making context. The decision-making context includes the transportation mode available or planned, populations of interest, geographic scale, and other factors, as well as the agency decision point that the selected measure is intended to inform (e.g., system or corridor planning, programming, or project design).
As transportation agencies increasingly adopt data-driven and strategic approaches to decision making, the need for measures that can inform those decisions is also increasing. Yet identifying and implementing meaningful accessibility measures can be challenging. To date, there is no standard practice for the selection and use of accessibility measures from among the wide array of accessibility metrics, methods, and tools. Research is needed to characterize and evaluate existing accessibility measures and identify valid and feasible measures for a range of decision-making contexts. To improve current and future practice, research must be coupled with guidance and support for implementation.
The objective of this research is to develop a practitioner-ready resource for transportation agencies on how to select and apply accessibility measures for different decision-making contexts. The resource will include guidance for immediate and mid-term actionable steps for transportation agencies to implement accessibility measures. The project will also include engagement with state departments of transportation (DOTs) and their partner agencies in implementation of accessibility measures.