with nine bridges built, 14 tunnels constructed, and road surface covered with gravel, the highway was opened to vehicular traffic in May 1932.

Nonetheless, the northern portion of the highway, between Su-ao and Taroko, was just 3.56 m in width, permitting only one-way traffic at a time. Vehicles were required to travel in convoys, controlled by six turnouts along the route. With no guard rails to speak of and falling