Case study 

Evaluating an intermodal yard layout with simulation

CSX Transportation

CSX Transportation built its largest intermodal yard layout near Chicago using state-of-the-art technology. Employing a simulation system, we evaluated a given layout, identified capacity bottlenecks and created an improved layout that increased yard capacity by over 15 percent.


Increase in capacity​


Received Arema Engineering Award

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CSX wanted to evaluate the yard for efficiency, because executives wondered whether the proposed layout could meet the yard’s projected processing capacity.

Business problem

CSX Transportation was ready to build a large new intermodal yard with a capital investment of approximately $200 million. The yard was expected to handle over 30 trains and process about 2,500 cars per day. After an engineering company designed the layout for this yard, CSX wanted to evaluate it for efficiency, because executives wondered whether the proposed layout could meet the yard’s projected processing capacity. CSX also wanted to know whether it was the best layout for the given budget and if its capacity could be increased by changing the layout. CSX hired Optym to create the best possible layout so the company could have confidence in the yard’s ability to process the projected number of cars.

Our approach

We spent several weeks visiting different intermodal yards, learning the processes and documenting them in detailed flow charts. After we hand-simulated yard processes on paper to further verify them, we built a detailed discrete-event simulation system to model the movement of trains in the yard. This simulation used complex time-space-based algorithms to route trains in the yard to avoid conflicts and collisions. Our new yard layout displayed all train movements through animation and visualization. Next, we validated the simulation system by simulating an existing intermodal yard and comparing important key performance indicators (KPIs) in the system with those in the yard. In addition to ensuring that the KPIs were sufficiently close, we performed a visual validation of train movements in the yard. Once we validated the accuracy of the simulation system, we used it to analyze the layout that the engineering company provided to CSX. By simulating the yard, we repeatedly identified yard bottlenecks and diligently removed them, mostly by improving the overall layout. We also considered different traffic volumes and determined the maximum volume that the yard could handle without being choked.

Key benefits

  1. Our unique and novel layout improved the yard’s processing capacity by over 15 percent without any significant increase in capital investment.
  2. Our new design created tens of millions of dollars in value.
  3. Our new yard layout included tracks of different sizes, instead of all tracks of similar size, which enabled blocks of different sizes to be classified efficiently.


When the yard went into production in 2011, CSX executives decided to use our recommended design to build the yard. This project received the 2011 Arema Engineering Award, a national award given to the best railroad engineering projects. CSX’s Intermodal division considers this yard simulation project to be a great success story.

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