An improvement to the roadway is desired from Philmont Scout Ranch to Springer in northeastern New Mexico. Alternative N (for north) costs \(\$ 2,400,000\) initially and \(\$ 155,000 /\) year thereafter. Route SA (for south, Alternative A) will cost \(\$ 4,200,000\) initially, and \(\$ 88,000 /\) year thereafter. Route SB is the same as SA with wider lanes and shoulders. It costs \(\$ 5,200,000\) initially with maintenance at \(\$ 125,000 /\) year. User costs considering time, operation, and safety are \(\$ 625,000\) for \(\mathrm{N}, \$ 410,000\) for SA, and \(\$ 310,000\) for \(\mathrm{SB}\). The salvage values for \(\mathrm{N}, \mathrm{SA}\), and SB after 20 years are 20 percent of initial cost, respectively. Using a MARR of 7 percent and a 20 -year study period, which should be constructed?

a. Use an incremental \(B / C\) analysis.

b. Use a \(B-C\) analysis.

c. Which route is preferred if 0 percent interest is used?