Integration of passenger and freight transport: A concept-centric literature review

The integration of passenger and freight transport has been the subject of debate among scholars from the beginning of the century, with a peak observed in the last five years. Considering the relatively recent interest in the topic, most authors have highlighted the heterogeneous and explorative approaches adopted so far, indicating a lack of systematic analyses. This is confirmed by the different names given to the same concept (e.g., co-modality, cargo hitching, system with mixed passengers and goods, share-a-ride, integrated passenger and freight logistics, and collaborative passenger and freight transport). This study conducts a comprehensive literature review based on the scientific contributions indexed in Scopus and selected through a semiautomatic data extraction. First, a descriptive analysis is conducted, which includes types of publication, geographical areas, sources of publication, research methods, and research design adopted. Then, a text mining analysis identifies the main content-related aspects, including a semantic investigation of the most frequently occurring terms, their clustering in homogeneous groups, the transport means considered, and the territorial scales that have been investigated. This analysis is used to define the future challenges related to the topic, which span from the provision of more robust quantitative analyses (studies providing real data and adopting ad-hoc models are still very limited) to policy-related issues. However, the definition of a normative framework that integrates both systems is essential to deal with passenger–freight transport in a combined manner.