Optimization of express line performance: numerical examination and management considerations

Improving the waiting process at checkouts in stores is an important goal of operations management in the era of time-based competition. The paper presents a method for evaluating the effect of express lines on the waiting process. An optimization model is developed which minimizes the average waiting time in line with respect to the maximum number of items allowed in the express lines. The research is based on a real case of a do-it-yourself superstore, but the methodology applied at the store can be used generally. The optimization model includes sensitivity analyses. Sensitivity analyses show how the optimal value of the limit parameter changes if major parameters of the model change. The results of these analyses help managers make decisions about short and medium-term operations of express lines. The major conclusion of the paper is that the optimal operation of express lines does not improve the average waiting time significantly, but the effect of non-optimal operation can be very unfavorable. Therefore, a successful implementation of express lines requires a thorough analysis of operational issues and a careful consideration of perceptional issues as well.