This 5km expessway tunnel was constructed in unique geological conditions of central Taiwan.
Tunnel Description
  • Tunnel width:

    10.5m, including two 3.75m lanes and two 1m walkways.

  • Clearance height:


  • Total cross section:

    115 ~ 120 square meters.

  • Design speed limit:

    80 kilometers/hour.

  • Cross passages:

    3 for vehicles and 9 for pedestrians.

  • Facilities:

    Control systems for air conditioning, lighting, electrical supply, traffic surveillance, fire protection, etc., and one vent shaft (240m deep and 9.5m inner diameter).

If you're traveling on the road in Taiwan, one thing is for sure, you will be passing through or overtop some of its beautiful mountains, even if your destination isn't the world famous Tarako Gorge or Alishan mountain resort. That's because nearly two-thirds of Taiwan is made up of a rugged and geologically complex formation of steep mountain ranges stretching from the foothills of the northern capital Taipei to the beaches on the southern tip of the island in Pingtung. Getting from one part of the island to another part may sometimes be a painstakingly difficult or time-consuming task, however, with the progess of economic development and arrival of some of the latest forms of technology, new tunnels and highways featuring expressway tunnels are emerging from the landscape, thereby making the road a much safer and more comfortable place.

Among these new tunnel projects connecting various parts of the island is the Pakwashan Tunnel (pronounced Bah-Gwa-Shan), a 5 kilometer long twin-tube expressway tunnel on the Hanpao-Tsaotun East-West Expressway linking the two counties of Changhua and Nantou in central Taiwan. The Pakwashan Tunnel stands out not only because it is the second longest roadway tunnel in Taiwan, but also because it is situated in the Tokoshan Gravel Formation, a layer of gravel with sand having geological conditions never encountered before in other construction projects, and requiring design considerations much different from that of rock tunnels. Therefore, the observations and engineering knowledge gathered from this special project and experience will serve as an invaluable reference for other gravel tunnels constructed in the future.


In March 1993, the Directorate General of Highways contracted with CECI to carry out the surveying, testing, geological investigation, planning and design of the Pakwashan Tunnel. After a careful evaluation, the New Austrian Tunneling Method (NATM) was adopted for the design, and supplementary methods were selected for drainage and grouting. Construction for the project began in November 1996 and its completion and opening to traffic in April 2005 marked a major milestone in the advancement of tunnel engineering technology in Taiwan.