To explore the cumulative ecological effects of roads in ecologically fragile areas, the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) tool was applied to assess the spatiotemporal changes in habitat quality, water yield, and soil erosion in road-effect zones of the Western Sichuan Plateau, China. Then, generalized estimating equations were formulated to analyze the impact of synergies among road attributes, climate, topography, land cover, and other factors on ecosystem service changes. The results showed that the habitat quality within the road-effect zones was mostly affected by road grade and structure, and water yield and soil erosion were attributed to the factors of road structure, rainfall, and topography. Roadbed sections had the greatest negative impact on ecosystem services, followed by bridge sections and tunnel sections. Overall, the results of this study address habitat encroachment and soil and water loss in ecologically fragile areas, contributing to knowledge on green infrastructure planning.