Territorial Sorting into Segmented Opportunity Structures: Commuting Networks and Formal Labour Market Access in a CEE Metropolitan Region

Abstract Metropolitan commuting flows reproduce the spatial organisation of registered employment. In FDI-led metropolitan regions, investment concentration generates a network with asymmetric branching: the core functions as a dense, multi-branching node connecting workers to diverse employment, while peripheral territories enter thin, single-path segments regardless of travel time. We reconstruct commuting network topology from mobile network signalling data covering approximately 150,000 daily flows in Cluj County (NUTS3), Romania, matched to the full registered employer dataset of the Cluj Territorial Labour Inspectorate. The analysis proceeds in four steps: destination field topology, time-threshold access dynamics, exposure to destinations outside the registered employment field, and PPML gravity models of flow formation. The results trace this branching asymmetry across each step. At the 90-minute threshold, 69% of peripheral origin territories retain zero direct network access to the core. Flows toward destinations with no detectable registered employment rise from under 1% in the core to nearly half of all peripheral flows, reversing the proximity gradient between registered and extra-registry opportunities. Gravity estimates show that peripheral origins operate under a distinct flow formation regime that travel-time reductions do not alter. The territorial implication is direct: transport-time investment reaches a structural plateau, and peripheral access depends on diversifying the registered employment base at origin rather than on shortening the corridor to the core. The paper reframes metropolitan inequality as differential territorial insertion into the registered employment opportunity structure, and identifies branching degree expansion in peripheral localities as the structural condition for effective labour market policy.