Application of multicriteria analysis to select the best highway alignment(Reprinted from Tunnels under Pressure)

Selecting the optimal alignment is a multi-disciplinary decision problem, w ith objectives which may conflict with one another. The approach selected f or resolving this problem in a quantitative manner, is the Multicriteria An alysis, where ratings are attributed to different objectives, for the alter natives analyzed. The following principal objectives were considered for th e highway project under consideration: minimization of the impact on the en vironment, optimization of the functionality of the alignment (also, in ter ms of safety), minimization. of construction time (with respect to the 60-m onth deadline), minimization of construction and operational costs, and max imization of the results of the economic investment. In order to perform an evaluation of the possible alternatives it was necessary to breakdown thes e objectives into a set of corresponding criteria. Definition of a weightin g factor for each criterion, signifying the importance of the criterion in the decision making process, was done by pair-wise comparison, quantitative criteria and experts' judgment. A rating system was defined for evaluating the performance of each alternative solution. Minimization of construction time and minimization of construction and operational costs are amongst th e criteria with the highest weighting factors in selecting the optimal alig nment. The software chosen for providing the hard data for this comparison was DAT/SIMSUPER. Due to the complexity of the alignment (viaducts, tunnels , normal road sections), a very large network of construction activities ha d to be set up. The selected alignment was that of alternative A5 since, ap art from being associated with low construction cost and time, it was also associated with a favorable performance with reference to the other princip al objectives: impact on the environment, alignment geometry, and investmen t maximization (C) 2001 South African. Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.