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July 2012 www.sname.org/sname/mt POLB is one of the largest port facili -ties in the United States, second only to the adjacent Port of Los Angeles (POLA). POLB has multiple marine terminal facil -ities that provide shipping services for intermodal containers. To accommodate a continued expansion in trade, POLB is investing heavily in upgrades to the termi -nals. Construction is underway on the new Middle Harbor Terminal, which combines three older existing intermodal terminals into a single state of the art terminal, with deeper, wider slips and modern container handling equipment. A new intermodal terminal is proposed for Pier S on Terminal Island; the terminals at pier G and pier J are also slated for upgrades. Accommodating the growth involves more than just waterside changes. e Class I railroads that service the ports have sig -nicantly upgraded their infrastructure to provide service for the intermodal market, adding additional tracks through Cajon Pass and elsewhere. is area is vitally important to the railroads: intermodal trac provides close to a quarter of their revenue. Still, congestion is increasing, and in Southern California, traffic and environ -mental issues are continual challenges. e ongoing expansion within this busy port area is subject to intense public scrutiny. In 2008, about a quarter of the contain -ers handled at the port were loaded directly on to rail cars at marine terminals (on-dock rail), while the remaining three-quar -ters were transported into or out of POLB by truck. Some of the truck-transported containers were consumed in Southern California, and a few continued east by road, but close to half of them were brought to intermodal facilities in East Los Angeles and elsewhere to be loaded onto transcon -tinental trains. Loading more of these containers in the port using on-dock rail is a way to address environmental concerns by reducing the number of local and regional truck trips. e reduced trac congestion and shorter truck queues at the terminal access gates have obvious air quality and quality-of-life ben -ets. On-dock rail also reduces the time to get containers to their ultimate destination, beneting shippers. e port?s goal is to load about 35% of intermodal containers using on-dock rail. However, the lack of current infrastruc -ture limits the amount of cargo moved by on-dock rail today. e challenge for POLB is to update the infrastructure within severe land and site layout constraints. Project background The POLB Rail Master Planning effort, completed in 2006, identied the need for a central rail yard to support on-dock inter -modal operations. e proposed location for the yard is the pier B area, which cur -rently includes a small rail yard with limited usability. The new pier B yard (PBY) will need to provide the capability to receive and depart 10,000 ft. trains, and store rail cars waiting to enter an on-dock terminal or to leave the port. e proposed PBY site has a number of physical constraints that limit the size and design of the proposed rail yard. ese include the adjacent I-710 free -way corridor, the Dominguez Channel, the Alameda Corridor, and city boundaries, as well as surface streets and residential and commercial neighborhoods. e Port?s engineering contractor devel -oped dozens of rail yard concepts that would t into this area. Some of the concepts were dedicated 100% to rail support; other hybrid designs included locomotive servicing facil -ities or a small intermodal lifting yard (for loading containers to/from trucks), at the expense of storage capacity. e concepts spanned a range of sizes, with different combinations of arrival/departure tracks and rail car storage. Each of the concepts had good points, but it was difficult to objectively decide which features were most benecial or even how big PBY should be. Decision makers at the port decided to use simulation modeling to filter out non-feasible alternatives and quantify the dierences. POLB had expe -rience with modeling, having conducted previous simulation efforts to analyze mainline rail capacity in the POLB/POLA area. However, the previous analyses did not focus on the terminal rail infrastruc -ture needed to support on-dock operations and volumes. e modeling team and engi -neering team worked together to develop a three-phase ?building block? modeling approach to support the various stages of the PBY design process, using the discrete-event simulation capabilities of the AnyLogic sim -ulation package. Discrete-event simulations represent a system as it changes over time. Each time the system changes, its state is re-evaluated and any subsequent changes are scheduled. Discrete-event models are commonly used to evaluate machinery and transportation systems, including rail. en Wh at can be built vs. what should be built As with any good analysis, the first step was to define the question that needed to be answered. e dozens of con -cept drawings had already answered the question, ?what can be built?? based on general objectives and the constraints of the planned site. For each concept, a typ -ical detailed simulation model would answer the question, ?does this particu -lar concept work?? Because by denition this approach needs the details of the con -cept, it is most often used later in a project, when those details have been engineered. For PBY, the team needed to lter out those concepts that were not able to sustain the primary operating objectives and volumes before all the details were developed. us, simulation modeling was used early in the decision process to identify ?what should be built?? is area is vitally important to the rail -roads: intermodal trac provides close to a quarter of their revenue. The terminal at pier G in the Port of Lo ng Beach is slated for upgrade.