Calculate supply and demand
Logistic nodes are used in supply chain and logistic chain models that use economic input-output characteristics to calculate supply and demand for each economic sector with an assignment of goods to logistics families to determine the spatial patterns of supply and demand. The logistic nodes are used as means to distribute or disseminate the external movements to internal zones. These nodes are places such as major goods yards, multimodal terminals, railway stations, and distribution centers where trip chaining of long-distance flows occurs.
The freight forecasting modeling process involves the representation and modeling of the long-distance logistics system in the Transport Logistics Node model. This model is only applied on the long-distance flows. These are defined as flows from the internal area (for example the greater southern California area) to the external area (the remainder of the United States as well as entry points to/from Mexico and Canada) and flows from the external area to the internal area. Data was collected through a shipper survey conducted for 131 locations in Southern California combined with rail operator data obtained at six intermodal terminals.
The following are some of the critical issues that need to be addressed: