From Sidewalk Audit to Intervention Priorities: A Transparent, Low-Data Protocol for Sustainable and Inclusive Pedestrian Mobility in Central Blida, Algeria

Walking is the most sustainable and socially inclusive urban travel mode, yet in many rapidly transitioning cities, obstructed and inaccessible sidewalks undermine it, and walkability assessment tools rarely tell municipalities where to act first. This study develops a transparent, low-data protocol that converts a micro-scale sidewalk audit into an ordered set of candidate intervention priorities, using 52 street-unit sides nested within 26 street units in central Blida, Algeria. Twenty audit variables were aggregated into eight obstacle families and normalised to occurrences per 100 m using digitised street-unit lengths (170–1255 m). A two-profile k-means partition, retained as an operational triage device and stable under street-unit bootstrap resampling, separates lower- and higher-obstruction sides. A random forest with SHAP attribution, validated with folds grouped by street unit, provides an internal ranking of the families that separate the profiles: normative accessibility (27.3%), bulky waste (22.6%), and structural defects (15.9%) lead, with threshold-like effects, and the ordering closely matches simple between-profile contrasts (Spearman ρ = 0.98). Normative accessibility leads under all robustness checks, whereas the order of the second-tier families depends on the number of profiles. Physical works and use regulation carry similar shares of attribution (49.4% and 45.4%); excluding accessibility deficits, which record missing provisions rather than occupied space, shifts the lead clearly to use regulation (62.5%). A minimal agent-based model illustrates how local detours can produce a nonlinear loss of pedestrian performance. The result is a reproducible, low-cost workflow that helps resource-constrained municipalities direct limited budgets towards safe, accessible, and inclusive sidewalks, in line with Sustainable Development Goal 11 (targets 11.2 and 11.7).