They don't take meal breaks
Gottwald's own calculations suggest that at facilities with significant labour costs (more than US$25 per man/hour) the use of AGVs can bring substantial annual costs savings. Apart from the primary accountable operating costs there are some secondary aspects that also contribute to the cost effectiveness:
AGVs don't take meal breaks, although they need (automatic) refuelling every few days AGVs can perform additional movements for, say, reorganising the stack, during idle berth time, with very limited cost. This can improve the handling performance for the next operation AGVs cause less damage than manually operated systems which can save several dollars per waterside handling move For estimating purposes, a twin lift AGV (CT60) shows the following characteristics: Lifetime: approximately, 50,000 running hours Estimated operating hours per year: 5,000 Average operating cost per hour during the lifetime (without initial investment but including fuel cost of € 0.60/litre diesel):
€ 11 - 15/hr (CT 60 E) € 13 € 18/hr (CT 60 H) (This range is due to the uncertainty of hourly maintenance labour cost and available expert services. ) In order to make a proper, forward thinking selection between various handling systems (tractor-trailer, SC, AGV) you have to study and compare alternative handling systems based on actual transportation services (average handling, peak performance, travel distances, waiting in interchange areas, etc). But Gottwald's own studies and experience in Rotterdam and Hamburg have shown that the AGV will incur the lowest annual operational cost compared with both tractor-trailer and straddle carrier systems.
