Human factor is a core consideration in transport planning so as to safeguard public safety. At the early design stage of a mega project, interactions between human behavior and future provisions are complicated to be understood, taking railway stations as an example. In order to demonstrate smooth passenger flow, acceptable Level of Service (LOS) and evacuation time to be within required design limitations during traffic peak hours at a critical design year, passenger flow simulation shall be conducted to verify the practicality of a station design. Human behavior can then be better understood using a crowd simulation model – MassMotion. MassMotion is an in-house pedestrian flow modelling software developed by Arup. Its result output can be in formats of screenshots, maps and 3D animation. These output provide realistic visual experience for our clients, designers, architects and engineers to identify critical areas for design improvement, such as bottleneck, congestion or conflicting movement from a passenger viewpoint walking inside a railway station. MassMotion has been widely used in various projects around the globe as an engineering solution to enhance design performance. In view of the COVID-19 pandemic, usage of MassMotion has surged to simulate social distancing situations using its Proximity Analysis tool.