%0 Journal Article %T Topological Effects and Performance Optimization in Transportation Continuous Network Design %A Jianjun Wu %A Xin Guo %A Huijun Sun %A Bo Wang %J Mathematical Problems in Engineering %D 2014 %I Hindawi Publishing Corporation %R 10.1155/2014/490483 %X Because of the limitation of budget, in the planning of road works, increased efforts should be made on links that are more critical to the whole traffic system. Therefore, it would be helpful to model and evaluate the vulnerability and reliability of the transportation network when the network design is processing. This paper proposes a bilevel transportation network design model, in which the upper level is to minimize the performance of the network under the given budgets, while the lower level is a typical user equilibrium assignment problem. A new solution approach based on particle swarm optimization (PSO) method is presented. The topological effects on the performance of transportation networks are studied with the consideration of three typical networks, regular lattice, random graph, and small-world network. Numerical examples and simulations are presented to demonstrate the proposed model. 1. Introduction The network design problem (NDP) involves the optimal decision on the expansion of an urban street and highway system in response to a growing demand for travel. It has emerged as an important area for progress in handling effective transport planning, because the demand for travel on the roads is growing at a rate faster than our urban transport systems can ever hope to accommodate, while resources available for expanding the system capacity remain limited. The objective of NDP is to optimize a given system performance measure such as to minimize total system travel cost, while accounting for the route choice behavior of network users [1]. The decisions made by road planners influence the route choice behavior of network users, which is normally described by a network user equilibrium model. Mathematically, the bilevel programming is a good technique to describe this hierarchical property of the NDP with an equilibrium constraint. Generally the upper level problem is to minimize the total system cost and the lower level problem is to characterize the UE traffic flow pattern ([2, 3]). Studies have been overwhelmingly focused on the continuous network design problem (CNDP) and substantial achievements in algorithmic development have been made. Abdulaal and LeBlanc [4] formulated the CNDP under deterministic user equilibrium (DUE) as a bilevel programming model and the Hooke-Jeeves heuristic algorithm was also introduced. As an application, Friesz et al. [5] used a simulated annealing approach to solve the multiobjective equilibrium network design problem as a single level minimization problem. Marcotte [6] transferred the CNDP into a single %U http://www.hindawi.com/journals/mpe/2014/490483/