Integrating a tactical harvest-scheduling model with a log sort-yard location model

Abstract

Failure to sort logs prior to their transportation to a mill can result in a loss of value in the forest products supply chain—for unsorted, higher value logs can be used in a low-value product where lower valued logs would otherwise suffice. To capture this lost value, a log sort-yard facility is used in the forest products supply chain. The sortyard is located between multiple forest locations (supplies) and multiple mills (demands) and functions to grade, scale, buck and sort logs before they are trans-shipped to mills where the demand for their value is highest. The problem of selecting the location of a sort-yard has been modeled by other researchers, but prior models have assumed that the locations of both log supplies and mills were fixed. In reality, the locations of log supplies are not fixed, but are selected using a multi-period, tactical harvest-scheduling model. The objective of this work is to formulate, test, and evaluate a model that simultaneously selects the location of cutblocks and the location of a sort-yard over time. This prototype model was tested on a small, toy data-set. Three scenarios were evaluated: a no sort-yard scenario, a fixed sort-yard scenario, and a scenario allowing the sort-yard to change location over time. Results revealed that the selection of cut blocks was highly sensitive to the changes in the scenarios, and that the approach of simultaneous optimization can lead to improved planning in the forest products supply chain.