A transfer station ships municipal solid waste to a regional landfill in transfer trailers with a 20 ton payload. The round-trip haul distance is 120 mi and the hauling contract pays USD 2.85 per mile of travel. Transfer station processing costs USD 7.40 per ton. The combined processing and haul cost is most nearly:
- (A)USD 15.95 per ton
- (B)USD 17.47 per ton
- (C)USD 24.50 per ton
- (D)USD 41.60 per ton
Show worked solution
Answer: (C)
Haul charges of 17.10 USD/ton over the round trip plus the 7.40 USD/ton processing fee total 24.50 USD/ton.
Haul payment is earned on every mile travelled, so the stated round-trip distance already covers the loaded and the empty leg.
Payload sets the accounting basis, because one trailer carries the whole load charge.
Transfer station processing is already quoted on a mass basis and adds without conversion.
FE Reference Handbook — Engineering Economics: Cost Estimation, Unit Cost Basis
Why the other choices appear
- (A)Halves the given distance to a one-way 60 mi haul: 60 x 2.85/20 + 7.40 = 15.95 USD/ton.
- (B)Treats the 7.40 USD/ton processing fee as a per-load charge: (342 + 7.40)/20 = 17.47 USD/ton.
- (D)Doubles an already round-trip mileage to account for the return leg twice: 2(342)/20 + 7.40 = 41.60 USD/ton.