A new highway is to be constructed. Design A calls for a concrete pavement costing $ per foot with a -year life; paved ditches costing $ per foot each; and box culverts every mile, each costing $ and having a -year life. Annual maintenance will cost $ per mile; the culverts must be cleaned every years at a cost of $ each per mile. Design B calls for a bituminous pavement costing $ per foot with a -year life; sodded ditches costing $ per foot each; and pipe culverts every mile, each costing $ and having a -year life. The replacement culverts will cost $ each. Annual maintenance will cost $ per mile; the culverts must be cleaned yearly at a cost of $ each per mile; and the annual ditch maintenance will cost $ per foot per ditch. Compare the two designs on the basis of equivalent worth per mile for a -year period. Find the most economical design on the basis of AW and PW if the MARR is % per year.