Understanding key factors affecting underground logistics systems adoption and front-end planning: A cross-sectoral investigation and insights into emerging mobility solutions

Recent progress in the underground logistics systems (ULS) heralds a move closer to the prospect of low-carbon automated freight movement utilizing electrified tunnels and pneumatic pipeline technologies. However, amidst the array of novel concepts, the industry's understanding of the enablers and barriers of ULS remains incomplete. This paper introduced an analytic framework for both public and private sectors to revisit the ULS plans in a nascent stage. Through a comprehensive document review, we delineate the typical approaches to initiate ULS from the perspectives of government and consortia. Fifty-four factors characterizing the sponsors' visions, project startup prerequisites, and implementation barriers were identified. We conducted semi-structured interviews and a two-round Delphi survey with 18 experts to elucidate how these factors influence ULS adoption and explore causal relationships in new system front-end planning. Subsequently, a grounded-theory framework was constructed to interrelate multi-thematic concepts. Our research findings indicate several key points: (i) the gestation of ULS project is a collaborative effort between public and private sectors looking for shared visions and common interests; (ii) the unilateral promotion of emerging transport systems/modes could face diverse barriers and disadvantages due to the complexity, uncertainties, and lack of precedents; (iii) positioning ULS programs within a public-private partnership agreement fostered by incentive policies is crucial to achieving social, technological, and business preparedness for transformation. This paper contributes to the understanding of cross-sectoral conception and arrangements of logistics modal shift from road to underground with sustainable development goals. It also offers novel insights for freight transport system adoption and policy-making.