Modeling horizontal and vertical equity in the public transport design problem: A case study

In the transportation literature, equity has been and is still used with a variety of meanings and purposes. Traditionally, equity has been considered in strategic transport planning but very few works have been addressing it in a quantitative way, detailing how to explicitly consider it at a transportation design level (tactical and/or operational) focusing on the consequent social role of transportation. This paper deal with how quantitatively incorporate spatial and social equity principles in the Transit Network Design Problem. With respect our previous preliminary study, this paper goes a step further in the definition of the solution to the problem, proposing a starting candidate route set generation procedure as preliminary step to solve before the main optimization. The objective function considers at the same time the cost of users, operators and unsatisfied demand, and a comprehensive horizontal and vertical equity indicator is also specified among the constraints of the problem. An extensive sensitivity analysis investigates how the costs of the system vary with respect to the achieved level of equity. Then, an application to a real case of study is presented to validate of the proposed methodology and highlight its usefulness and performances.