Optimization and Engineering Application of Mountain Highway Alignment Schemes Based on Topographic and Geological Constraints

Abstract

This study establishes a multi-source constraint factor system for mountain highway alignment selection based on “topography–geology–engineering” considerations. Elevation, slope, terrain relief, valley incision density, hazard susceptibility, distance to fault fracture zones, and engineering design indicators are uniformly transformed into spatial constraint intensities. Furthermore, a geological hazard risk penalty mechanism is introduced, and an alignment optimization method integrating “risk assessment–constraint transformation–path search–scheme verification” is developed. The A* algorithm is employed for path searching. The proposed method is applied and validated in a county road reconstruction project in Tibet. The results show that, compared with the traditional river-following scheme, the recommended scheme reduces the route length by approximately 8.0%, decreases the length traversing high-risk areas by about 83.3%, lowers the average constraint intensity by approximately 33.9%, and achieves the optimal comprehensive evaluation value. The study demonstrates that the proposed method can transform geological hazard risk from a qualitative avoidance condition into a quantitative optimization constraint, thereby enabling proactive disaster avoidance and comprehensive optimization of mountain highway alignment schemes. The results can provide technical support for route selection decision-making in complex mountainous areas.