Urban street-lighting grid extension and night-time women's market stall operating hours in Tanzanian municipal wards: a boundary-discontinuity estimation of feeder-line proximity

Street-lighting grid extension is typically evaluated by counting connected premises, yet the outcome that matters for women who trade after dark is the length of the working night at market stalls whose access to the feeder line is discontinuous. The design is specified for municipal wards in Tanzania, where feeder-line extension proceeds premise by premise and where women's stalls cluster along the same streets. It then calibrates the design against the DHS Program indicator 'Mother's first postnatal checkup: Less than 4 hours' (RH_PCMT_W_L4H), using 82 country-survey observations from 33 African countries between 2005 and 2025, with a mean of 39.187 and a standard deviation of 20.446. That calibration is used only to fix the sample-size and precision arithmetic that a ward-level study would need; it is not a substitute for the stall-level data the design requires. The contribution is a transferable specification for evaluating lighting-grid extension as a boundary phenomenon rather than a binary treatment.