Abstract
Belt and Road investment has produced an unprecedented expansion of transport capacity along the historic Silk Road, yet almost all was built for freight, not people. The question is under what conditions a freight corridor converts into a functioning international heritage–tourism corridor, defined independently of the conditions by cross-border tourist flows, multi-country itineraries, heritage-node use, and integrated tourism products. This study developed a five-condition conversion framework—a heuristic scorecard, not a validated model—comprising a gateway condition, scheduled cross-border passenger service (C1); two facilitating conditions, mobility facilitation (C2) and single-transaction ticketing (C3); a heritage-access condition, heritage-proximate nodes (C4); and a sustainability safeguard, absorptive capacity (C5). This study applies it to the Trans-Caspian, China-Central Asia, Southern (Iran-Türkiye), and China-Laos Railway corridors, drawing on UNESCO, operator, timetable, and tourism-demand sources, 2021–2026. Only the China-Laos Railway corridor (Kunming-Vientiane) shows the clearest signature of conversion—growing cross-border passenger flows to heritage-proximate nodes—though multi-country itineraries and integrated products are inferred, not directly observed. It satisfies C1 and C4 but only partially C2, C3, and C5, showing ticketing integration and a common third-country visa are enablers, not preconditions, and conversion does not secure sustainability. Measured against this benchmark, the western corridors are heritage-rich but constrained by C1, C3, and C4—scheduled service, interoperable ticketing and heritage-serving routing—not by heritage endowment or visa policy: these are institutional, not capital, problems. Modal analysis shows the emissions-minimizing rail configuration distributes visitor expenditure most widely. This study argues that cross-border passenger volume, not freight tonnage, should be a headline corridor indicator.