Guogang Railway Tunnel

A group of three single-track tunnels on the Coastal Line (海線) in Houlong, Miaoli. These tunnels were driven through the hills at Guogang (過港) rather than along the shore, where winter monsoon winds would have buried the tracks in sand. Completed between 1920 and 1921 and opened with the full coastal line in 1922, they have brick upper arches over concrete lower walls, with each of the six entrances shaped differently to suit the unstable ground; the south portal of the first tunnel extends some twenty meters as a shelter against the wind-driven sand. Excavation exposed a bed of marine shellfish fossils, later protected as the Guogang Shell Fossil Layer (過港貝化石層) under Japanese colonial era heritage law. The tunnels were abandoned in 1973 when the line was rerouted west to ease its grades and curves, converted into a cycling and walking path between 2009 and 2011, and listed as a historic building in 2015.