3. An engineering company has presented three designs to improve traffic flow at a major intersection in a heavily traveled suburban area. The first alternative involves traffic signaling. The second alternative includes traffic signal improvement and intersection widening for exclusive left turns. The third alternative includes extensive reconstruction, including a grade separation structure. The construction costs, as well as annual maintenance and user costs are listed in the following table for each alternative. Determine which alternative is preferred based on the economic criteria if the analysis period is 20 years and the annual interest rate is 15 percent. Show that the result is the same using the present worth, equivalent annual cost, and the rate of return methods. Annual CapitalMaintenance Annual User Salvage Costs (S) | Costs Value(s), (5) 15,000 10,000 9,000 8,000 Alternative Costs (S) Present condition Traffic signals Intersection widening Grade separation 450,000 890,000 1,350,000 500,000 401,000 15,000 350,000 11,000 301,000