20. Alternative Ranking Using Criterium Decision Plus (Multi-attribute Utility Analysis)

Transcription

1 The selection of the preferred alternative, using a structured decision process, begins with creation of the decision hierarchy. The hierarchy is the clear organization of the goal, listing of categories of criteria, listing of the criteria, and generation of the alternatives under consideration. The goal of this case (highlighted in yellow) is to Select the Preferred Alternative. Step 1 of 18

2 The stakeholder working committee (representing the multiple perspectives of the community) summarized the core issues into five categories. These categories (highlighted in yellow) reflect the spectrum of issues that must be considered when selecting a preferred alternative. Step 2 of 18

3 The categories have been further refined to criteria. These criteria (highlighted in yellow) are the measurable elements in which all of the alternatives are rated. Step 3 of 18

4 The alternatives for this case are a combination of an interchange (I, II, or III) and an intersection (letter designation). These were developed in a process separate from the criteria development process. Step 4 of 18

5 Scales must be developed for each criterion to produce a numerical rating of the alternatives performance. The scales may be either quantitative or qualitative. An example of a quantitative scale is the Total Project Cost criterion scale of $107M to $53M. Step 5 of 18

6 An example of a qualitative scale is the 2 through 4 scale for the Bike, pedestrian facility connectivity criterion. Step 6 of 18

7 All alternatives are rated against the scales of the criteria. The ratings were produced by the stakeholder group with technical detail from the project consultant team. Step 7 of 18

8 To reflect the importance of each category, they are assigned different weights. The weights of the categories were developed by the stakeholder team. The number represents the percent of contribution of the category to the total benefit calculation. Step 8 of 18

9 The criteria within each category are also assigned different weights to reflect their relative value. The weights of the criteria were also developed by the stakeholder team. The percent represents the contribution of the criterion to the specific category. Step 9 of 18

10 The resulting total contribution of the individual categories and criteria are calculated by multiplying the weight of the category and the weight of the criterion and displayed within each box of the decision hierarchy. For example, the Total Project Cost criterion contributes or 15.2% to the decision score, and the Air Quality criterion provides 4% contribution. Step 10 of 18

11 The results of multiplying the contributing weights and the ratings produces a benefit score. The higher the benefit score, the higher the expected benefit from the corridor. The alternatives are listed in the first column, the benefit score in the second column, and a graphical representation of the benefit score in the third column. The resulting total benefit scores for these alternatives range from to Step 11 of 18

12 The decision scores serve as method to rank the alternatives. Alternative I-A has the highest score which represents the most best performing alternative relative to the categories and criteria. This screen shows the ranking of the alternatives. Step 12 of 18

13 The contributions of each category to the decision score is summarized on this screen. The stacked, colored bars represent this contribution. Alternative I-A has a greater contribution to its decision score by the Human Environmental and Transportation categories than the others. The greater contribution by a category to an alternative, the better the alternative performs in the criteria within the category. Step 13 of 18

14 The contribution can be further broken down to the contributions by the individual criterion to the decision score. This screen shows the six criteria that individually contribute the most to the decision score. Step 14 of 18

15 Sensitivity of the weights may also be assessed with this model. This screen is a sensitivity graph of the Light/glare impact criterion. The colored lines represent the decision score of the top five alternatives. As the vertical red line is shifted to the right (increasing the weight of this criterion) or the left (decrease the weight), the decision score of the alternative changes. This changing decision score may produce a change in the rank of the alternatives. Step 15 of 18

16 In order to change the ranking of the top five alternatives (a cross-over of the colored lines), the weight of light/glare impacts would have to increase by a factor of four. The red vertical line shows the location of the cross-over. Step 16 of 18

17 Some criterion provide no change in the rank of alternatives as the weight changes. The horizontal lines that do not cross represent this condition. Step 17 of 18

18 This structured process serves as a platform for selecting a preferred alternative. In this case, alternative I-A meets the values of the stakeholders better than any other. Step 18 of 18