Weighted Decision Matrix

After having finalized the designs for all viable alternatives, the team needed to compare and select the design that was the most  viable alternative. Thus, the team used Caltran's Weighted Decision Matrix. This matrix would be made up of different factors that were important to the designs. Each factor was included because of their importance to the project and were given an appropriate weight based on their importance.

 

As seen from the chart below, there are varying degrees of weights depending on the factor. Local circulation is a major factor as two of the project's purpose were to reduce local congestion and to provide additional access to users. Thus, this factor received the full weight of 9. Freeway Impact is just as crucial as there would be little benefit to a project that had negative results on existing conditions. Therefore, it was assigned a weight of 8. The benefits/cost that each alternative would generate over a 20-year period were calculated and taken into consideration as the third highest category in the Weighted Decision Matrix. This category was assigned a weight of 7. A detailed cost and benefit analysis of each alternative can be viewed in the Cost/Benefit Analysis page in this website. Accessibility is ranked fairly high as well due to the fact that it addresses multimodal transportation: cars, bikes, pedestrians. This category was given a weight of 6. User Experience is also important as some interchange layouts are foreign to some and a familiar layout is more comfortable for users. Thus, a weight of 5 was assigned. Environmental Impacts were rated with a weight of 4, because each category had a varying level of impact on existing conditions. In addition to these major factors, some minor factors were also addressed including R/W impacts, construction cost, and constructability. Though these minor qualities are still important to the design, they are not the primary reasons to consider building an alternative; these minor factors were assigned a weight of 3 to 1, respectively.

 

After assigning weights to each of the categories, each alternative was given a score from 1 to 10 based on how well the team thought that the alternative performed in a given category. These ranks were then multiplied by the weight for a score. Finally, each score was summed up and we end up with a final score for each alternative, as shown in the chart below.

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