Spatial Analysis for Bridge and Road Site Selection: A Multi-Criteria Decision Framework for North and Northeast Thailand

Abstract

This study is part of a master plan by Thailand's Department of Rural Roads to design new bridge and road construction projects across 37 provinces in the North and Northeast regions. Potential sites were evaluated based on physical accessibility and environmental factors, considering eight criteria including slope, road density, distance from existing bridges, accessibility to educational institutions, workplaces, tourist sites, hospitals, agricultural areas, and villages. Using multi-criteria decision-making (MCDA) and the Analytical Hierarchy Process (AHP) within a GIS framework, we assessed origin-destination trips to identify optimal sites for new bridges and roads. Initially, 1,534 potential bridge locations were identified and evaluated using AHP to determine the relative importance of each factor. The GIS-based MCDA process enabled effective spatial data analysis, refining the sites based on environmental constraints and proximity to existing structures. Ultimately, 185 suitable locations for bridge construction were selected, including 98 sites in Northern Thailand and 87 in the Northeast. The study demonstrates the effectiveness of combining AHP and MCDA within a GIS framework for infrastructure planning. It underscores the importance of integrating multiple criteria to achieve sustainable and efficient development. The findings offer a robust framework for policymakers to identify and prioritize infrastructure investments that address both current and future needs.