the highway begins in the west at dongshi district in taichung. the highway used to go up into the central mountain range along the dajia river () valley through the townships of guguan () and cingshan (). at lishan there is a branch that heads north to yilan city. it goes through the mountains to dayuling () which is the highest point of the route. here another branch of the highway runs south from dayuling to wushe (). continuing east from dayuling, the highway goes down into taroko national park. it passes through guanyuan (), cih-en (), luoshao () and tiansiang () before entering taroko gorge. after the gorge the road then meets the eastern coastal su'ao-hualien highway.