Baguashan Tunnel between Lincuo IC. and Zhongxing JCT. was the longest highway tunnel (4.9 km) in Taiwan when opened to traffic in April 2005, although the top rank moved to Hsuehshan Tunnel in National Highway No. 5 in June 2006.
The exact route west of the Provincial Highway No. 19 is undetermined. However, there is an alternative route connecting to West Coast Expressway (Provincial Highway No. 61).