Workflow congestion in a facility layout

Traditional facility layout research ignores workflow congestion and tends to focus on distance-based transportation cost. Recently many authors have identified workflow congestion as a major concern in a facility layout, yet few analytical models have been proposed. This paper attempts to address this concern in the following way. First, we formalize the concept of workflow congestion, which incorporates a variety of workflow interruptions. We establish a probabilistic model for workflow interruptions and develop a method for evaluating the expected travel time through an aisle. We then formulate the facility layout problem as one for minimizing the total expected travel time, i.e., we focus on alleviating workflow congestion. A solution approach based on "sliding bottleneck paths" is also presented.