A pavement engineer in the City of Tullahoma in Coffee County is considering three maintenance and rehabilitation (M\&R) alternatives for a section of roadway at the Northgate Mall. The treatments vary from moderate to aggressive: treatment A (thin AC overlay) costs $75,000; B (thin AC overlay and local digouts) costs $100,000; and C (base repair and patch) costs $150,000. The pavement condition is currently at a PCI of 45 (it is 8 years old). Treatment A is expected to extend the pavement's life by 3 years; B by 5 years, and C by 8 years (beyond its originally expected useful life of 15 years). The figure below shows the diagram that the engineer has drawn to help him evaluate the M\&R options available. Treatment A will increase the PCI by 7,B by 10 and C by 12 . In all cases, routine maintenance costs amount to $10,000/ year. The interest rate is 6%. a. Which treatment offers the best alternative? (State all your assumptions). (Hint: Consider the benefit of each alternative as the product of condition and time captured by the area under the curve). b. Identify two of the most important limitations with the analysis you have conducted. (Not to scale)