Final answer:
The round-trip break-even time for solid waste collection systems is calculated by comparing the costs of using self-loading compactors directly to the disposal site versus using a transfer and transport system.
Step-by-step explanation:
To calculate the round-trip break-even time for solid waste collection systems using self-loading compactors versus a transfer and transport system, we must consider operational costs as well as capacity and weight differences. The self-loading compactor has a volume of 30 cubic yards and a specific weight of waste capacity at 600 pounds per cubic yard. In contrast, the tractor-semitrailer transport unit has a volume of 105 cubic yards with a waste specific weight of 325 pounds per cubic yard.
Calculations would involve determining the cost of transporting waste directly with the self-loading compactors, which include the operational cost and the cost per weight of transported waste. Then, comparing that to the cost of transporting waste using a transfer station, which adds transfer station costs and additional unloading time costs but potentially reduces the number of trips due to higher capacity of the transport unit.
The operational costs are $40 per hour for the self-loading compactor and $60 per hour for the tractor-semitrailer. Additionally, we have a transfer station operational cost of $3.25 per ton and an extra unloading time cost for transport units at $0.40 per ton. It's a matter of economics to check at which point the round-trip times for direct haul and transport via a transfer station would cost the same, thus finding the break-even point.