Highway Alignment Optimization Incorporating Bridges and Tunnels

A three-dimensional highway alignment optimization methodology is developed that automatically determines whether and where bridges or tunnels are preferable to embankments or deep cuts, respectively. This is done by comparing the optimized costs of such alternatives. The data for detailed computations of earthwork, right-of-way, vehicle operation, user time, and other costs are obtained from a geographic information system (GIS) for each alternative alignment considered. The alignment optimization process relies on a genetic algorithm developed for this problem. Two example studies implemented in an artificial study area with a real GIS show that by modeling bridges and tunnels we can improve the reliability and adaptability of highway alignment optimization as well as find more practical solutions than otherwise.