Urban development-induced redevelopment of informal settlement footbridges and women's pedestrian market-circuit formation in Lagos: a difference-in-differences estimation of bridge-demolition exposure

Urban redevelopment in Lagos routinely removes informal footbridges that women traders use to move between residential settlements and periodic markets, yet the consequences for market-circuit formation are rarely specified in a form that supports causal estimation. The design is motivated by a mechanism in which demolition raises the effective distance between residence and market, shifts the gender division of transport labour, and re-routes traders through intermediaries whose margins alter the viability of repeated visits. Identification rests on comparing settlements on opposite sides of a demolished bridge with settlements on comparable corridors where a bridge remained standing, before and after demolition, with exposure defined by pre-demolition pedestrian flow rather than by post-hoc outcomes. The paper specifies the treatment, comparison, outcome and covariate structure, states the parallel-trends assumption and the threats to it, and sets out the event-study and heterogeneity specifications that would permit estimation. It does not report estimates. The contribution is a falsifiable design for a question that Lagos redevelopment policy has so far posed only descriptively, and a set of boundary conditions under which the design would and would not identify the effect of interest.