An AGVS will be implemented to deliver loads between four workstations: A, B, C, and D. The hourly flow rates (loads/hr) and distances (m) within the system are given in the table below (travel loaded denoted by "L" and travel empty denoted by "E"). Load and unload times are each 0.45 min, and travel speed of each vehicle is 1.4 m/sec. A total of 43 loads enter the system at station A, and 30 loads exit the system at station A. In addition, six loads exit the system from workstation B each hour and seven loads exit the system from station D. This is why there are a total of 13 empty trips made by the vehicles within the AGVS. How many vehicles are required to satisfy these delivery requirements, assuming the traffic factor is 0.85 and the reliability (availability) is 95%?

Hourly rate loads/hr) Distances (m) A B C D A95 80 150 65 75 80 To A B C D 18L 10L 15L -121 From A 22L D 30L, 7E