Service systems are usually classified in terms of their number of channels . A single-channel queuing system, with one server, is typified by the drive-in bank with only one open teller. <br /><br /> <br /><br />If, on the other hand, the bank has several tellers on duty, with each customer waiting in one common line for the first available teller, then it is a multiple-channel queuing system. <br /><br /><br /> <br /><br /><br /><br /><br />Same case can be considered for many situations in construction industry . Resources of repetitive construction projects and truck concrete mixer delivery are two examples. <br />The first figure below shows the mechanism of the procurement of resources in a repetitive construction project while the second figure shows the mechanism of the delivery of concrete by truck mixers . Both mechanisms contains queuing . <br /><br /> <br /><br /> <br />