Accessibility planning in American metropolitan areas: Are we there yet?

Proffitt, D., Bartholomew, K., Ewing, R. and Miller, H.J. (2019) “Accessibility planning in American metropolitan areas: Are we there yet?Urban Studies, 56, 167-192.

Abstract.  Transportation-planning researchers have long argued that the end goal of a transportation system is increasing accessibility, or opportunities for individuals to meet their daily needs, but that US practice tends to focus on increasing mobility, or opportunities to travel farther and faster. This study finds evidence that the gap between theory and practice may be closing when it comes to accessibility, but that significant barriers still exist to the wider adoption of the accessibility paradigm among metropolitan planning organisations, the main entities responsible for regional transportation planning in the USA. We measure this gap by creating an accessibility index based on content analysis of a nationally representative sample of 42 US regional transportation plans (RTPs). We then use regression-tree analysis to determine the characteristics of metropolitan areas that are most likely to employ accessibility concepts. Finally, we identify barriers to a wider adoption of the accessibility paradigm. Most RTPs include accessibility-related goals, but few define the term or use accessibility-oriented performance measures. The lack of clarity on accessibility leaves vehicle speed as the fundamental criterion for success in most plans. Our analysis finds that MPOs serving large regions with high per capita income are the most likely to produce plans that focus on accessibility. We argue that such places produce more accessibility-oriented RTPs because they have greater planning capacity and recommend changes to federal planning guidelines that could speed the adoption of the accessibility paradigm in RTPs.

New publication: Accessibility with time and resource constraints

Mahmoudi, M., Song, Y., Miller, H.J. and Zhou, X.  (2019) “Accessibility with time and resource constraints: Computing hyper-prisms for sustainable transportation planning,” Computers, Environment and Urban Systems, 73, 171-183


Accessibility is the ease of obtaining desired destinations, activities, or services in an environment. A common accessibility measure in basic and applied transportation science is the space-time prism (STP) and the network-time prisms (NTPs): these are the envelopes of all possible paths between two locations and times in planar space and transportation networks, respectively. STPs and NTPs focus on time as the scarce resource limiting accessibility. However, other resource constraints can constrain space-time accessibility, such as limits or “budgets” for energy, emissions, or monetary expenses. This paper extends NTPs to include other resource constraints in addition to time. Network-based resource hyper-prisms (RHPs) incorporate other resource constraints into NTP, capturing the trade-offs between time and other resources in determining space-time accessibility. We conceptualize RHPs as a constrained optimization problem and develop a forward and backward resource-dependent time-dependent dynamic programming to determine the boundaries of a RHP given time and other resource budgets. We illustrate our approach using the Chicago sketch network (with 933 nodes and 2967 links) for the use case of an individual with an internal combustion engine vehicle and a carbon emission budget and using portions of Washington, D.C. and Baltimore networks (with 12,145 nodes and 30,697 links) for the use case of siting electric vehicle charging stations to maximize regional accessibility.


Resource hyper-prisms; Space-time prisms; Accessibility; Sustainable transportation; Dynamic programming

Opioid Innovation Fund – Franklin County Opioid Crisis Activity Levels (FOCAL) map

OSU’s Opioid Innovation Fund is supporting CURA’s project, the Franklin County Opioid Crisis Activity Levels (FOCAL) map. We will be building mapping and spatial analysis tools to understand the social factors associated with opioid overdoses and barriers to effective treatment.  This campus-community partnership involves Harvey Miller (CURA), Ayaz Hyder (College of Public Health), Lauren Southerland (OSU Wexner Medical Center). David All (WellHQ), Gretchen Hammond (Mighty Crow Media) and Sherri Kovach (Central Ohio Trauma System).