Zhuziling Tunnel

The first Zhuziling Tunnel opened in 1898 as part of the colonial realignment that replaced the steep Qing railway route over the ridge separating Keelung from the Keelung River. A gentler second tunnel opened alongside it in 1923; its brick lining and semicircular vault make it one of the last brick railway tunnels built by the colonial government, alongside the old Caoling Tunnel. It was retired in 2008 for a third tunnel driven through the filled-in first, after floodwaters from Typhoon Nari poured along the abandoned original into central Keelung in 2001. The surviving entrances to the second-generation tunnel are now half-sealed with concrete, and proposals to convert the tunnel into a bicycle route have been floated as of the mid-2020s.