## 2 Literature Review  
In general, how well a service meets the expectations of the customers can be referred to as service quality. [11] defined the service quality as: \"the degree and direction of dis  
Figure 1: Research methodology adopted for the study. -repancy between customers' service perceptions and expectations.\" However, there is no consensus on the definition of service quality. A summary of the concept of service quality can be found in [12]. Although the concept of service quality may seem difficult to define, its importance for organizations, institutions, and companies is beyond doubt. Similarly, the concept of customer satisfaction is not straightforward. In general, customer satisfaction can be referred to the assessment of the perceptions of customers about their expectations of the quality of a particular service and the actual quality that the service offers. In general, the basis of the customer satisfaction is perceived by its value, which specific products or services are able to offer. A summary of the literature of the concept of customer satisfaction can be found in [13]. A user satisfaction survey is a common way of determining passengers' satisfaction regarding the quality of a transport service. The key factors affecting passengers' satisfaction of the service quality can be determined and subsequent improvements can be made to increase the passengers' satisfaction levels [14]. There are numerous studies that have attempted to study customer satisfaction in Public Transportation. Public transport is often characterized by different users, so it is necessary to analyze a number of variables in order to optimize the service. These include socio-demographic variables, which show gender inequality in some countries [15], social exclusion [16] considering for example age distribution, but also variables related to travel habits [17; 18] and travel distance [19]. The exploration of public opinion is also of great importance for the implementation of planning strategies by local authorities and can, therefore, also help service companies in the optimal definition of transport, reducing the use of private transport and thus promoting decarbonization [20; 21; 22]. The efficiency of DRT services and the optimization of the transport offer can be defined by analytical models developed and applied to real cases by identifying critical demand thresholds for alternative modes. They can highlight the trade-offs between cost and service level that a transport operator or mobility provider has to consider in order to implement a successful service [23]. A study conducted in Agartala, India, concluded that comfort and flexibility are the key factors affecting passengers' mode choice behavior [24; 25] found that public transport users valued waiting time, cleanliness, and comfort the most. A study conducted in Scotland found three underlying factors affecting passenger's perception of quality of service in public transport. The underlying factors were identified as convenience, cabin environment, and ease of use. Females were found to show relatively negative opinions about cabin environment [26; 27] employed factor analysis to explore the underlying factors affecting the transit ridership and the levels of satisfaction when using transport services. They found that comfort, safety, and information are the factors that residents value the most, whereas the tourists were found to place more focus on service production, reflecting route frequencies and reliability of service. [28] found that cleanliness and ventilation in the vehicle are likely to increase user satisfaction of the quality of service of public transport system. A study conducted in three different cities of Indonesia on passengers' perceptions about para-transit found that security was the first and foremost concern for passengers in all the three cities [29; 30] found three factors, namely comfort, performance, and assurance, affecting perceived service quality of public transport among young passengers.