INCORPORATING NETWORK IMPACT ANALYSIS INTO ROAD ALIGNMENT OPTIMIZATION

In existing literature on road alignment optimization, only some cost factors related to the road itself are considered. But actually a new road is not only an isolated transportation facility, but also obviously a component part of a road network. The impact of the new road on the original network is valuable and could not be ignored. In this paper network impact analysis is incorporated into the road alignment optimization model. Each road alternative can change the topology structure of the original network. As for each alternative, flow characteristics of OD traffic on the links are obtained through traffic assignment, and thus changed travel time and environmental load of OD traffic on the network can be estimated. They are converted into monetary equivalents and are regarded as the benefit incurred by the alternative. The ratio of benefit to cost is used as the objective function to evaluate each alternative. Genetic Algorithm is employed to solve this model.