  Locational measures of accessibility are widely used in urban and
transportation planning to understand the impact of the transportation system
on influencing people's access to places. However, there is a considerable lack
of measurement standards and publicly available data. We propose a generalized
measure of locational accessibility that has a comprehensible form for
transportation planning analysis. This metric combines the cumulative
opportunities approach with gravity-based measures and is capable of catering
to multiple trip purposes, travel modes, cost thresholds, and scales of
analysis. Using data from multiple publicly available datasets, this metric is
computed by trip purpose and travel time threshold for all block groups in the
United States, and the data is made publicly accessible. Further, case studies
of three large metropolitan areas reveal substantial inefficiencies in
transportation infrastructure, with the most inefficiency observed in sprawling
and non-core urban areas, especially for bicycling. Subsequently, it is shown
that targeted investment in facilities can contribute to a more equitable
distribution of accessibility to essential shopping and service facilities. By
assigning greater weights to socioeconomically disadvantaged neighborhoods, the
proposed metric formally incorporates equity considerations into transportation
planning, contributing to a more equitable distribution of accessibility to
essential services and facilities.
