Yilan City
In Yilan County, the highway finally leaves the mountainous region and enters Yilan Plain, but not before a stretch of curvy mountain roads. The highway passes through Toucheng, Jiaoxi, Yilan City, Wujie, Luodong, and Dongshan before entering Su'ao. From Su'ao to Hualien, the highway is designated as Su-Hua Highway (蘇花公路), a set of curvy mountain roads known for its sharp curves and cliffs along the route. Su-Hua Highway passes through Su'ao and Nan'ao in Yilan County, Xiulin and Xincheng in Hualien County before entering Hualien City. In Xincheng the highway intersects Central Cross-Island Highway, which provides access to Taroko National Park.