A Transport Network Staging Decision Optimization For The City Consisting Of A Group Of Islands

Residents in a group of islands always have inter-island travel, these travel are based on inter-island waterway transport. Compared to the travel of inland city, sea way travel has disdavantages of travel time-consuming, inflexible and easily affected by climate, residents in a group of islands is not convenient, need to change the traffic network through urban traffic planning. The transportation construction projects of inter-island generally sea bridge and tunnel, this kind of transportation construction projects have the characteristic of huge investment, long construction period, difficult construction, ever one-time transport network decisions are making for short-term transport network, the decisions do not consider the construction period of each transportation construction projects, the projects can not affect the traffic network in the same time, it is necessary to introduce the concept of time dimension into traffic network decision, change the one-time traffic network decision to staging decisions to meet the actual situation of traffic network planning study in a group of islands.Based on the analysis of the urban traffic network design theory and traffic network optimization problem, we build a bi-level programming model about traffic network staging decision on time dimension, in the upper model, the transportation construction investment is a constraint, traffic travel time and traffic travel environmental index is two factors in the objective function, to solve the optimal transportation network staging decision scheme, the lower model based on the Wardorp equilibrium theory, the travel time of transport network user is the objective function and the traffic assignment is user equilibrium traffic assignment. In this paper, we solve the upper model with genetic algorithm, the lower model with user equilibrium traffic assignment method, and the realistic traffic network decision for a group of islands is marking as an example, to obtain a scientific and rational transport network staging decision scheme, to verify the applicability and effectiveness of the model and the algorithm.