###### Abstract
In traditional thinking and research, service quality is often evaluated as either good or bad based on sophisticated indicators for each attribute, and improving bad service quality is believed to increase customer satisfaction and repurchase rates [7]. However, in a complex reality, if you blindly invest in the improvement of unreasonable service attributes, you cannot know the impact on customer satisfaction, which often prompts companies to face the dilemma of increasing sunk costs with no improvement in operating performance [8]. Mass transportation is very important for national development both economically and socially, especially in reducing residents' living costs. In addition, having a good public transportation system, a variety of modes of transportation, and convenient and reasonable prices also helps tourists decide to travel to Thailand as well, resulting in the growth of the Thailand tourist industry. Based on the survey results of the Office of the Permanent Secretary of the Prime Minister's Office on the number of complaints, it was found that the BMTA was the state enterprise with the highest number of complaints on average. The most complaints about the BMTA's bus service regarded the quality of drivers, fare collectors, bus conditions, increasing numbers, expanding routes, services, and travel convenience [9]. People in Bangkok spend a lot of time and expenses traveling without being able to predict the time spent traveling [3]. While Bangkok already has the BTS SkyTrain and MRT subway, these do not cover all the routes available in Bangkok. The bus services in Bangkok are deployed to cater to locales beyond the purview of the BTS SkyTrain and MRT subway. The commuters still need to use the public bus for transport. Despite the interconnectivity of bus and subway stations, the schedules of the two modes of transportation do not always align perfectly. In addition, residents also rely on buses for transferring to other modes of transportation such as water transport and trains. Therefore, bus service still plays a crucial role as a mode of transportation for the residents. However, in some areas of Bangkok, passengers have raised significant concerns about the physical amenities and dependability of the bus services [10; 11]. Enhancing the service quality of Bangkok's bus service is a crucial matter. The quality of bus service is a significant research topic in the field of public transportation. This means if passengers are satisfied with the bus's service quality, they will continue to use it and it can reduce the traffic problem, which tends to become more severe due to the increasing number of private cars. [PERSON] and [PERSON] [12] investigated the factors that affect the public bus transportation services quality in Bali Province, Indonesia. They identified six factors that influence the satisfaction of public transportation users in Bali: comfort, responsiveness, capacity, tangibility, safety, and reliability. Furthermore, [PERSON] et al. [13] conducted a study on customer satisfaction with bus service users in Cape Town, South Africa. The study found that the most important service quality items for customers were the helpfulness of staff, affordability of fares, and reliability of buses not breaking down. The study revealed that there are certain areas in need of improvement, specifically the travel time after boarding the bus and the availability of routes. Therefore, service quality is a critical issue that the public sector should consider to provide commuters with an attractive alternative to private cars. Service failure refers to any breakdown, flaw, or issue that occurs during the delivery of a service that leads to an unsuccessful service outcome or customer dissatisfaction. This affects the quality and reliability of the service; businesses are unable to deliver services that meet customer expectations, and issues are still not being resolved effectively until it may have a negative impact on the relationship with the customer.