Investigating of transportation systems development for urban districts, costs and social equity: a case of Sanandaj, Kurdistan

The transportation system is one of the essential subjects for any country because it directly concerns the daily costs and social problems. Researchers have proposed different methods to develop transportation systems, each with its strengths and weaknesses. This paper has proposed a new bi-objective mathematical model based on three social equity theories, the first of which considers infrastructure development costs for a transportation system and includes operational, environmental, and pollution costs. The second objective focuses on enhancing social equity in investment distributions in the transportation system for a long time. Three theories, including Utilitarianism, Rawl's, and Sadr's, were modeled and used to assess social equity. The model was examined for an original case of data in Sanandaj city, and an improved version of the augmented e-constraint method was developed to solve it. According to the general results, each social equity theory has its own merits. The results show that Rawls' theory, with minimum infrastructure costs, establishes the best social equity (70%) after 5 years of application; therefore, the Sanandaj city would be a sustainable city based on Rawls' theory which enhances region 1, and the three regions would be in balance after 5 years. Urban planners and transport network managers can use the developed model for equitable investment in an urban transportation system.