GIS-Based Approach to Dynamic Accessibility: Incorporating a User Perspective to Recognize Social Equity Implications

Accessibility is a common system performance measure that provides insights into the tangible benefits provided by a transit system. Although traditional accessibility approaches focus on improving service for existing users, it is also important to understand the needs of potential users when considering design changes. Traditional approaches have been improved with dynamic measures but are still weighted toward the needs of existing users, those in high density areas, and those traveling at peak times. Additionally, public transportation provides a way to reduce existing disparities in accessibility, but it is unknown how effectively current systems perform. Although existing methods use points of interest or existing travel patterns as a baseline for accessibility, the proposed methodology considers both origins and destinations unweighted to account for potential users that would be undervalued in traditional analyses. A user-oriented approach is proposed, considering access area and spontaneous trips. General transit feed specification data for the Champaign-Urbana Mass Transit District (CUMTD) were used with the proposed methodology to analyze the accessibility provided by the bus system. This analysis showed that CUMTD provided the highest accessibility in high density areas and equal levels of service across income levels and areas with varying rates of vehicle ownership. It highlighted reductions in accessibility faced by those traveling at off-peak hours and called attention to how the system did not provide higher coverage in low-income neighborhoods. The demonstrated methodology has broad applicability to understanding spatial-temporal variations in access, including for the case of public transportation.