A warehouse consists of five aisles of racks (racks on both sides of each aisle) and a loading dock. The rack system is four levels high. Forklift trucks are used to transport loads between the loading dock and the storage compartments of the rack system in each aisle. The trucks move at an average speed = 140 m/min (loaded) and 180 m/min (empty). Load handling time (loading plus unloading) per delivery totals 1.0 min per storage/retrieval delivery on average, and the anticipated traffic factor = 0.90. Worker efficiency = 100% and vehicle reliability (availability) = 96%. The average distance between the loading dock and the centers of aisles 1 through 5 are 200 m, 300 m, 400 m, 500 m, and 600 m, respectively. These values are to be used to compute travel times. The required rate of storage/retrieval deliveries is 100 per hour, distributed evenly among the five aisles, and the trucks perform either storage or retrieval deliveries, but not both in one delivery cycle. Determine the number of forklift trucks required to achieve the 100 deliveries per hour.