A new highway is to be constructed with two alternative designs.
Design A calls for a concrete pavement costing $90 per foot with a
20-year life; two paved ditches costing $3 per foot each; and three
box culverts every mile, each costing $9,000 and having a 20-year
life. Annual maintenance will cost $1,800 per mile; the culverts
must be cleaned every five years at a cost of $450 each per mile.
Design B calls for a bituminous pavement costing $45...