Highway investment planning model for equity issues

In the present study, we revised and expanded the basic model proposed in our previous study to better deal with equity issues in highway investment planning. The issues cover horizontal (intraregional) and vertical (interregional) equity of the accessibility or travel cost for cities as well as the equity of budget allocation among the cities. In this study, more constraints and decision variables were added to the model to handle the exclusive and complementary properties among alternatives. In addition, adjustments for travel cost measures and objective functions are proposed to justify the horizontal and vertical equity. The revised multiobjective model is estimated by fuzzy programming for the highway system in Taiwan. Our results indicate that the model is practical and effective for acquiring reasonable solutions for the goal of efficiency and equity in highway investment planning.