In one aspect a factory automation system for a wafer fab is provided. The factory automation system is adapted to facilitate cross-AMHS transfers of wafer lots within a semiconductor foundry. The factory automation system may include a first MCS and an associated first AMHS; a second MCS and an associated second AMHS; and a third MCS and an associated third AMHS. The system may also include a first bridge connecting the first AMHS and the second AMHS to allow a FOUP to travel between the first AMHS and the second AMHS. The system may also include a second bridge connecting the second AMHS and the third AMHS to allow a FOUP to travel between the second AMHS and the third AMHS. The system also includes a unified control unit in communication with the first, second, and third MCSs, the unified control unit for coordinating transfers of FOUPs between the first, second, and third AMHSs.