Transportation is crucial to a country’s economic and social development, with the railway system being a key component. Despite ongoing improvements, issues such as cleanliness, delays, and service quality persist. This study analyzed factors influencing passengers’ perceptions of railway service quality in Thailand through a survey of 1,059 passengers using Exploratory Factor Analysis (EFA). Five main factors were identified: station facilities, onboard facilities, staff service quality, safety confidence, and value for money, explaining over 60% of the variance. Demographic variables including gender, station location, travel purpose, and frequency of use significantly affected perceived service quality, with station facilities having the greatest impact. Based on these findings, five policy recommendations are proposed: enhancing cleanliness and station environments, reducing disparities between urban and suburban areas, tailoring services to travel purposes, incentivizing frequent users, and improving safety through personnel and technology. These strategies aim to improve service quality and better meet the needs of railway passengers across Thailand.