The importance of the traortation and its role as one of the most essential foundations of national economy has been well established. One of the issues within the field of traortation is the selection of the traortation investment projects amongst which the selection of the projects dealing with the construction of the new streets or the expansion of the existing streets is of great interest. Although much research has been dedicated to the above-mentioned area, none has solely focused upon the expansion of the streets existing within the urban traortation network. The prime objective of the current study is to select a set of streets within the urban traortation network to enable the expansion purposes (e.g. in terms of budget constraint) as well as to optimize the travel time within the network. To fulfill the aforementioned goal, a mathematical model for the selection of projects within the urban network is proposed for the situations in which merely the expansion of the existing streets is required. Then, an innovative algorithm is introduced to determine the set of candidate streets for expansion purposes. Since the problem of project selection within the urban traortation system is an NP-hard problem from the solution perspective, with one of its most time demanding components being the solution of the traffic assignment sub-problem, and given that the expansion of the existing streets does not change the body and topology of the base network, an innovative algorithm is proposed to solve the traffic assignment problem in this situation, followed by the particle swarm optimization meta heuristic algorithm to solve the project selection model.
