Decision Analysis of Alternative Highway Alignments

The evaluation of alternative alignments for a proposed highway project in California required taking into account impacts on a variety of environmental and socioeconomic issues. Techniques of formal decision analysis were used to evaluate the overall impact of each alternative alignment and to rank the alignments in an ascending order of the overall impact. A multiattribute penalty function was calibrated using acceptable trade‐offs among impacts on different issues as assessed by a project team of scientists and planners. Results of decision analysis suggested that one of the alternative alignments should be most preferred under a variety of assumptions and value judgments. This alternative was recommended for further analysis and inclusion in a draft environmental impact report/statement. The application of decision analysis to this evaluation problem was effective because it: (1) Provided a rational procedure to address multiple and often conflicting environmental and socioeconomic issues; (2) facilitated sensitivity analysis to evaluate the impact of perceived value judgments of different concerned groups on the ranking of the alternatives; and (3) provided a full documentation of the evaluation process.