Arup was commissioned by the Related Companies to provide engineering design and documentation for the ventilation systems serving the east rail yard area within the Hudson Yards development. The existing rail yard storage area used by the Long Island Rail Road (LIRR) is to be enclosed with a structural platform, to provide a base for one the largest developments in the United States. LIRR will continue to use the space beneath the platform during and after construction. Mechanical ventilation systems will be required within the enclosed space to maintain conditions for the LIRR area; both in normal operation and to for smoke purge during a fire event. Arup has been working on this project for over two years providing fire and ventilation modeling as well as CFD analysis to confirm the performance of the systems for the new design.