Commodity businesses in The Dow Chemical Company rely on large and expensive fleets of railcars to ship their products to market. In some cases a fleet can be shared by several sites and businesses. Managing such a fleet while balancing the level of empty and full rail cars at each site is a complex problem due to variations in demand, production, inventory targets, transit time, etc. A Discrete Event Simulation model was developed to represent the operation and management of a shared railcar fleet. This model was used to make decisions that will reduce freight, inventory, and railcar switching costs while maximizing the utilization of the fleet.