# Integrated People and Freight Transportation:
## 1 Introduction  
Logistics processes that support freight transportation are changing rapidly due to unprecedented growth. This development also leads to changes in freight transport flows in all transport modes [1]. In this context, many studies and suggestions regarding the future of transportation are put forward. The integration of people and freight transport is one of the main current transportation issues discussed, and there are many studies [2, 3, 4, 5] that address this issue as a current issue. The Commission of the European Communities [6] emphasized that for free-flowing cities and towns, local governments should handle all urban logistics related to people and freight transport as an integrated logistics system. Promoting urban mobility by integrated people and freight transportation (IPFT) has recently attracted increasing attention [4]. However, the scarcity of studies in this field still attracts attention. Given the relatively recent interest in the topic, most authors have noted the lack of systematic analysis [3]. It has been suggested that integrating people and freight flows can create advantages to meet the same transportation needs with fewer vehicles and emissions [7]. Furthermore, integrating public and goods flows has been proposed as a valid approach to promoting efficient and sustainable transportation [8]. Collaborative urban public transport services ensure the seamless movement of people and goods, and the negative impacts of existing urban public transport systems can be reduced [9]. This integrationcan reduce the adverse effects of urban logistics activities, such as noise, traffic congestion, and pollution, by reducing the number of fossil fuel vehicles traveling for goods transportation [10]. Figure 1 shows the IPFT system. This example specifies a distribution center (DC) and public transport routes (train and bus connections). Packages are transported to the stops/stations by trucks from DC. It is then transported by bus or train. The goods unloaded at the stops where customer delivery can be made are delivered to the customers by urban vehicles. This system can be expanded with different transport modes. The study aims to systematically examine and describe integrated freight and people transportation and present its opportunities and challenges. While examining within the scope of IPFT in the study, many terminologies such as cargo hitching, freight on transit, urban co-modality, crowd-shipping, occasional drivers, crowdsourced delivery among friends, and share a ride are discussed. Strategic, tactical, and operational decision problems are considered as review criteria. In the study, the literature on the IPFT is comprehensively examined, an overview is presented, and it is aimed to create a road map for future studies. In particular, no study has been found in which terminologies are explained in such detail and the entire research scope is discussed together. We can summarize our main contributions as follows:  
* We review terminologies related to IPFT. Terminologies related to IPFT, which is still a new concept, continue to develop. Therefore, we present the terminologies (cargo itching, freight on transit, urban co-modality, crowd-shipping, occasional drivers, crowdsourced delivery among friends, and share a ride) mentioned so far. * We examine the studies carried out for IPFT in the context of strategic, tactical, and operational decision problems. We also search and classify studies dealing with uncertainty under a separate heading for these three problem dimensions. * Based on a comprehensive review of existing research, we address the opportunities and challenges of IPFTs. While we evaluate opportunities from an economic, social, and environmental perspective, we address challenges from a PESTEL perspective. We present real studies conducted to provide application examples of the IPFT concept and a user background. * We present suggestions regarding IPFT for future studies and practitioners.