Question: A rail guided vehicle system is being planned as pan of an assembly cell. The system consists of two parallel lines, as in Figure. In operation, a base part is loaded at station I and delivered to either station 2 or 4, where components are added to the base part. The RGV then goes to either station 3 or 5, respectively, where further assembly of components is accomplished. From stations 3 or 5, the product moves to station 6 for removal from the sys-tem. Vehicles remain with the products as they move through the station sequence; this, there is no loading and unloading of parts at stations 2, 3, 4, and 5. After unloading parts at station 6, the vehicles then travel empty back to station 1 for reloading. The hourly moves (parts/hr) and distances (ft) are listed in the table below. RGV speed - 100 ft/min. Assembly cycle times at stations 2 and 3 = 4.0 min each and at stations 4 and 5 - 6.0 min each. Load and unload times at stations I and 6, respectively, are each 0.75 min. Traffic factor = 1.0. Flow many vehicles are required to operate the system? Assume A = 1.0.
