Throughput in serial lines with state-dependent behavior

Experimental evidence suggests that production-line workers adjust their work rates in certain situations to prevent idle time. We refer to this as state-dependent behavior, in contrast to the state-independent behavior of machines. In this paper, we develop several models for the state-dependent behavior of production workers. We then use these models to analyze the relation of line length to throughput in these systems. We find that state-dependent behavior makes serial lines more efficient and reduces the detrimental effects that longer line lengths have on throughput. In some cases, line efficiency can actually increase with length. This is a result of a higher percentage of workers having two buffers to provide feedback on the state of the line. Further, we show that workers who both speed up when they are likely to cause idle time for others and slow down when they are likely to become idle themselves improve the overall efficiency of the line.