## 3 Review of Studies Related to MaaS in the Context of Multi-
### Review of Studies
In [98], policy implementation of multi-modal shared mobility considering both the supply and demand sides has been reviewed. The results showed that providing car sharing, bike sharing, and e-scooter sharing for first/last mile access to transit systems from the supply side can improve transport accessibility and reduce social inequality from the demand side. Implementation of multi-modal shared mobility calls for a collaborative partnership of service providers and government to jointly set a merit-based business model to improve infrastructure provision, and create smart applications. 12. Question: What is the planning process for implementing MaaS? Results: Despite many MaaS pilot projects have been executed in different cities, most related studies focus on the barriers and travel behaviors of MaaS users. There lacks a study on the planning process for the implementation of MaaS. The paper [99] reports the planning process for integrating the services of several transport operators, including public transport operators, a micromobility service provider and a taxi operator, into the MaaS demo site of Athens' in Greece. The planning of three travel cases was covered in this study: (1) multi-modal trips for work; (2) MaaS trips for tourists; and (3) interurban trips for work and shopping/leisure. 13. Question: How to develop an architecture for MaaS to tackle the potential threats? Results: MaaS relies on federations of transport service providers. Providers trade their resources to attempt to create multi-modal mobility solutions through coordination. Although MaaS may help generate multi-modal solutions for mobility flexibly, it comes with insider threat and security/privacy concerns. In addition, the emerging networks of ubiquitous, pervasive devices providing real-time data on objects and people called Cloud-of-Things for mobility provide potential attack surface for insiders. A study on the potential threat in MaaS is required. The study of [100] focuses on security and privacy issues from the perspective of an insider threat. The study classifies the potential threats into two types: the potential threats to individual operators and the potential threats to federated MaaS providers. Appropriate measures to mitigate the problems were proposed. An overlay networking architecture was proposed to constrain the data obtainable by insiders while optimizing the users' requests. 14. Question: Whether the way bus services might be offered will be changed under MaaS? Results: The potential benefits of MaaS are expected to have a profound impact on traditional transport services such as bus services. An important research question for traditional bus service providers is whether the way bus services might be offered will be changed under MaaS. This research question motivated the study reported in [85]. The study indicates that a new hybrid multi-modal contract setting driven by the mode-neutral customer experiences might change the way bus services will be offered under MaaS. 15. Question: How to design a mobility hub to achieve sustainability, performance and efficiency by reducing vehicle miles in the city and combining many multi-modal transport options for transferring passengers? Results: A well-designed mobility hub is vital for reducing vehicle miles in the city and provides accessible space as well as many multi-modal transport options for transferring passengers. Design of a mobility hub is an important issue to achieve sustainability, performance and efficiency. In [67], the authors proposed the methodology and analyzed the parameters for designing process of mobility hubs. Design parameters for a new mobility hub center are determined via expert opinions and literature review. The authors proposed an integrated methodology that consists of Fermatean fuzzy sets, Quality Function Deployment and visualization of mobility hub center. * Question: How about the competitiveness of MaaS travel options with respect to private car usage?