MINIMIZING TRANSPORTATION AND INVENTORY COSTS FOR SEVERAL PRODUCTS ONA SINGLE LINK

This paper deals with the problem of determining the frequencies at wh ich several products have to be shipped on a common link to minimize t he sum of transportation and inventory costs. A set of feasible shippi ng frequencies is given. Transportation costs are supposed to be propo rtional to the number of journeys performed by vehicles of a given cap acity. Vehicles may or may not be supposed to carry out completely all materials available, and products assigned to different frequencies m ay or may not share the same truck. Integer and mixed integer linear p rogramming models are formulated for each of the resulting four situat ions, and their properties are investigated. In particular, we show th at allowing products to be split among several shipping frequencies ma kes trucks traveling at high frequencies to be filled up completely. I n this situation, trucks may always be loaded with products shipped at the same frequency.