PM (Personal Mobility) is a new type of transportation mode, and the number of users is increasing rapidly due to convenience and portability. However, related research is insufficient and PM safety issues are constantly occurring. In this study, we analyzed the severity of PM accidents and analyzed PM accidents that occurred in 2017 and 2018. PM accidents were classified into four stages according to the severity of accidents. Factors affecting accidents were classified into road and environmental factors, accident type factors and human factors. And factors that significantly affected PM accidents were selected. As a result of the analysis, significant variables influencing the severity of PM accident were selected. Among the roads and environmental factors, May or the time zone at 14 and 21, 23 were found to be high in the severity of PM accidents. And when the road was wet or the accidents occurred at intersections of roads were found to be high in severity of PM accidents. If PM other driver's age was 50s, 60s or 70s, the accident severity was also found to be high. In the case of the PM and other vehicle's accidents, the severity of accidents was high when the other vehicle was bicycle and the driver's age was 40s, 50s. In the case of the PM and pedestrian's accidents, the severity was also high when the accident occurred at the sidewalk or during crossing the intersection. In case of PM-only accident, when the accident site was other place (except for crossroads, single lanes, bridges, tunnels, and parking lots), the severity was high.

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In suburban areas where the demand is not high enough, the fixed-route buses usually operate with infrequent services, which increase the cost of waiting transit services for fixedroute service users. For those low demand regions, flexible-route bus operations with doorstep services, which operate with flexible routes, flexible schedules, and smaller vehicles, can be a feasible alternative. This study formulates the social welfare for flexible-route bus operations under various financial constraints, seeking to jointly optimize the headway, fare, and zone size. Elastic demand functions are constructed as a part of problem formulations. Unlike many previous studies, this study does not presume the shape of the zone, so that the flexible-route bus services can be designed according to the geographical conditions in the regions. Moreover, the amount of subsidy for financially constrained policy is calculated based on the actual demand although many previous studies used the potential demand to calculate the subsidy amount. Numerical analyses are explored to evaluate and compare system-wide welfares for different financial perspectives, i.e., no financial constraint, break-even policy, and subsidized policy. The solution optimality for constrained nonlinear optimization problems is verified using analytical optimization or the Karush-Kuhn-Tucker (KKT) conditions. It is found that the welfare of subsidized transit operations is located between the welfare amounts of unconstrained and break-even cases; this finding of welfare variations over subsidy amounts can be a helpful resource for transportation mobility analysts in determining the appropriate service quality and the corresponding amount of subsidy. Sensitivity analyses are presented to explore the system-wide welfare with respect to critical input parameters, including a comprehensive analysis of the unit cost of bus operations, which offers implications toward Mobility-as-a-Service (MaaS) planning.