9-41 A do-nothing and two mutually exclusive alterna- tives are being considered for reducing traffic con gestion. User benefits come from reduced congestion once the project is complete, while user disbenefits are due to increased congestion during construc- tion. The interest rate is 8%, and the life of each alternative is 15 years. chosen? Which alternative should be Alternative A User benefits (SM/yr) User disbenefits ($M) First cost (SM) Operations and maintenance (SM/yT) 2.1 2.6 1.2 2.1 6.9 9.9 0.75 0.825 (a) Use the benefit-cost ratio. (b) Use the modified benefit-cost ratio. (c) Use the public/government version of the B/C ratio