A mass transit system, such as a mass rail transit (MRT), offers a high-capacity, high-speed, and reliable mode of transportation. With the rapidly growing population and escalating urbanization rates, it is a sought-after solution to mobilize more people with fewer space requirements. However, existing MRT systems might still be challenged with long lines and overcrowding, particularly during peak times. This study explores the potential of introducing an express train service in addition to the existing local train routes without purchasing new trains. The MRT-3 line of the Philippines was used as a case study. Commuters in MRT-3 face challenges such as long queues and overcrowding during peak hours. A simulation-based approach was performed to build a virtual representation of the existing train local service and then tested how the introduction of an express train service affects the average stay time of passengers, the average number of passengers waiting on the station platform, and the train capacity utilization. The FlexSim simulation software was used for modeling. Official data from the Department of Transportation was used to model passenger arrivals and departures per hour per station. A total of 8 alternative models were built. Each alternative created a new line for express trains that bypasses some stations and stops only at select stations with high demand. Station selection was based on their historical foot traffic. The results indicate that all proposed express service models effectively reduce average stay time and platform congestion while increasing train utilization. upon analyzing the changes in train utilization efficiency and daily foot traffic, the study recommends alternative 5, which has an express service that covers the 6 stations (out of 13) with the highest demand. The approach of this study offers valuable insights for improving urban transit systems, supporting the broader goals of sustainable urban mobility and efficient public transport infrastructure. Cost analysis of introducing the express train service is recommended for future studies.