The Republic of Korea Government has adopted a whole-of-government approach in the management of naturally occurring asbestos (NOA) through a nationwide asbestos management plan. Regional and detailed mapping, and examination of NOA effects are still ongoing for NOA management by indoor air, noise and asbestos management division, Ministry of Environment. Plans by the Korea Rail Network Authority are under way to rebuild the Janghang double-track railway. The proposed Jannghang double-track railway route is through an area of high NOA probability that has serpentine and ultramafic rock. Chrysotile, tremolite, and actinolite asbestos were among the rocks identified within the project site (initial planning line and the operational design line). The level of asbestos in most soils was low (≤0.25 percent), while some soils contained 0.75 percent asbestos. Monitoring and analyses of air quality revealed below 0.01 fibers per cm3 (f/cc). However, there were no traces of asbestos detected in the groundwater and stream water. Despite the low asbestos content of the soil and rock, the disturbance of NOA-containing soils and rocks during railway construction could trigger the release of asbestos fibers into the air. NOA mitigation plans and measures are necessary for workers and residents during the construction of the railway.