Public transport is the enabler of social and economic development, as it allows the movement of people and provides access to opportunities that otherwise might have been unattainable. Access to public transport is a key aspect of social equity, with step-free access improving the inclusivity of the transport network in particular for mobility impaired population groups. Thus, this study develops a two-step algorithm for determining the optimal allocation of resources for the refurbishment of stations to provide step-free accessibility in pubic transport networks. The first step consists of k-shortest path finding algorithm between every origin-destination pair in the network. The non step-free shortest paths are then fed into the second step of the algorithm, a mixed-integer linear optimization problem that selects the station to be refurbished considering inequality penalties as well as costs, budget and demand constraints. The developed methodology is applied to enhance the accessibility of the London Underground. In doing so, several demographic components, including economic background and disability reported, are parameterised and factored into the determination of the optimal solution. Our analysis produces a 15% increase in step-free trips compared to the current state of the network, as well as a reduction of approximately 60% in existing step-free detour time.
Unpublished: Centre for Transport Studies, Department of Civil and Environmental Engineering, Imperial College London, SW7 2BU, UK, October/2021