## 4 Review of Studies Related to Sustainability in the Context of Multi-Modal Mobility
### Review of Studies
The study focused on the role of mass transit in the area where automated mobility-on-demand is widely available. The simulation results indicated that, to avoid congestion and maintain acceptable levels of urban transportation service, mass transit is irreplaceable. 14. Question: Do the characteristics and motives differ between business-to-consumer carsharing adopters and peer-to-peer carsharing adopters? Results: Business-to-consumer carsharing and peer-to-peer carsharing are two business models for carsharing. Studying whether the characteristics and motives differ between B2C and P2P carsharing adopters is an important issue to promote carsharing. The study [57] focused on studying characteristics and motives of B2C carsharing adopters and P2P carsharing adopters in the Netherlands with different carsharing provider types to clarify their differences. The results of the study show that the characteristics of B2C and P2P carsharing adopters are very similar. The differences are in the frequency of using carsharing and public transport. The characteristics influencing a car owner to become an adopter of P2P carsharing as a provider were investigated. The study finds that car owners are much more likely to provide their car through an online platform if they already shared their car. The study suggests regulation to shape favorable conditions for connected multi-modal transportation systems rather than regulations for each carsharing business model. 15. Question: How to develop a model that incorporates various sustainability factors to provide decision support for sustainable household mobility choices in a multi-modal transport network? Results: In the study [73], a Petri Net model considering various sustainability factors to capture the dynamics of multi-modal journey options in a complex transport network was proposed. The factors along with travel time and cost in the route optimization process were combined into impact score. The study demonstrated the capability of the model to direct users make more sustainable mobility choices through simulation. The model provides a tool that can be used by policymakers to assess the impact of a variety of sustainable transportation initiatives and infrastructure investments. 16. Question: How to design a scheme to reward travelers who have adopted sustainable transport modes? Results: One way to promote sustainable mobility, alleviate congestion and reduce emissions is to reward travelers who have adopted sustainable transport modes. An interesting issue is to design a scheme to reward travelers who have adopted sustainable transport modes. In [58], a credit charge-cum-reward scheme was proposed. During a credit charge-cum-reward scheme period, a traveler may take transit to accumulate credits to minimize his/her travel costs. Alternatively, a traveler may choose to drive by consuming his/her credits. At the end of a credit charge-cum-reward scheme period, the government will settle the individual credit balance at a charging price for credit deficits or redemption for credit surpluses. An optimization problem was formulated based on consideration of the value of time and characterization of the periodic mode usage equilibrium. The authors defined a credit charge-cum-reward scheme to be Pareto improving if each traveler's periodic travel cost is reduced under the scheme. The authors defined a credit charge-cum-reward scheme to be revenue neutral if the government gains zero revenue under the scheme. The study proves that the proposed credit charge-cum-reward scheme is Pareto improving and revenue neutral. 17. Question: How to determine and analyze the patterns of the modal accessibility gap in cities? Results: There is a link between sustainability of cities and accessibility of different transport modes. Modal accessibility gap (MAG) refers to the spatial accessibility of different transport modes. Measuring MAG is one approach to assessing the degree of low-energy transport modes in cities.