In this paper we study a multi-echelon production/distribution system
where the retail centers are allowed to replenish their inventory thro
ugh a normal resupply channel to an expedited resupply channel by incu
rring an additional cost. An approximation scheme to find the operatin
g characteristics of such systems is developed. The results of a numer
ical study indicate that significant cost savings can be achieved by u
sing the policy suggested in this paper.