Davao City Bypass Construction Project Package I-1 Enters Peak Phase

― Technology Transfer in the Pioneering Philippines Mountain Tunnel Construction Project ―

  • Civil Engineering
  • Global

December 8, 2023

Shimizu Corporation <President: Kazuyuki Inoue>, in collaboration with Takenaka Civil Engineering & Construction Co., Ltd. and Ulticon Builders, Inc., a leading construction company in the Philippines, hereby announces the progress made by their joint venture on its portion of the Davao City Bypass Construction Project on the island of Mindanao. At more than 40% complete, the work is in its peak phase. This project is unique because it involves the construction of the country’s first full-scale mountain tunnel, showcasing a noteworthy technology transfer aimed at training Filipino engineers and workers with no experience in this type of work.

Funded through a Japanese yen loan, the Davao City Bypass Construction Project addresses increasing traffic, alleviates traffic congestion within the city, and enhances logistics in the largest economic zone of Mindanao centered around Davao City. Envisioned to contribute to the economic development of Mindanao, the 45-kilometer-long bypass connecting Sirawan in southern Davao City to Panabo City in the north will cut the travel time between the two regions in half, reducing it by around 50 minutes to less than an hour once complete.

After forming the joint venture in October 2018, Shimizu bid on the project in May 2019. The construction plan and other parts of the joint venture’s proposal for the mountain tunnel received high marks from the Department of Public Works and Highways of the Philippines, leading to a notice of award in March 2020 to award the contract. The formal contract, valued at approximately 28.2 billion yen, was signed in October of the same year. The joint venture constructs the central part of the bypass, measuring a total of 10.7 kilometers. The project consists of two 2.3-kilometer-long tunnels, one inbound and one outbound (the tunnel construction section), an 8.4-kilometer-long main road, and three bridges, with Shimizu and Takenaka Civil Engineering & Construction responsible for the tunnels.

Immediately following the announcement of the notice of award in March 2020, all Japanese staff members temporarily returned to Japan due to the worsening of the COVID-19 pandemic. Around October, when the construction contract was signed, Japanese staff were able to enter the Philippines and gradually return to Davao City. They received instructions to start the work in December 2020. Work commenced on the main road in April 2021, and after cutting an access road to the tunnel entrance, tunnel excavation began at the north tunnel entrance in November 2021 and the south entrance in April 2022. Tunnel excavation is underway for two tunnels, one each for Northbound and Southbound lanes, from the northern and southern tunnel entrances.

Concrete lining is simultaneously progressing at four different work zones. As of November 30, progress stands at 70.3% (1,580 meters/2,249 meters) for the southbound tunnel and 76.4% (1,711.6 meters/2,240 meters) for the northbound tunnel.

Notably, the ground in the tunnel construction area, predominantly composed of relatively soft strata called mudstone, necessitated support (auxiliary construction method) to prevent deformation and collapse of the tunnel walls (ground). However, three conditions made the shoring plan more challenging.

The first was that a stream crossed over about 200 meters from the northern tunnel entrance with only around 11 meters of earth covering. In this section, the ground was reinforced in advance in the direction of excavation, and a special ground improvement agent was imported from Japan to prevent earth collapses caused by water ingress. The second and third conditions were that the earth covering exceeded 100 meters, resulting in high earth pressure in the central part of the tunnel, and with only a 20-meter separation between the walls of the two tunnels, they were each impacted by the other’s excavation work. In Japan, shoring plans can be changed quickly according to ground deformation, but in the Philippines, it takes a long time to procure materials when plans are changed. As such, we made an effort to enhance the originally planned shoring to ensure ground stability.

As for technology transfer, our joint venture engineers are actively disseminating their expertise in constructing mountain tunnels in the Philippines. This includes forming mixed work teams of experienced Indonesians and inexperienced Filipinos at our worksites, holding regular online seminars, and presenting at civil engineering conferences. Development of human resources takes time, but we anticipate that our efforts here will contribute to the government’s vision of “the completion of tunnel construction work solely by Filipino engineers in the future.”

As suggested by the slogan, “Build Better More (BBM),” the Marcos administration is focused on infrastructure development. Our joint venture is committed to meeting government expectations through the timely completion and opening of the Davao City Bypass, coupled with technology transfer.

≪For Reference≫

Overview of Davao City Bypass Construction Project

Client Department of Public Works and Highways, Philippines
Location Davao City, Mindanao, Philippines
Project name Davao City Bypass New Construction
(DED and CS)
Nippon Koei, Nippon Engineering, Katahira Engineers in association with PhilKoei JV
Contractor Special construction joint venture of Shimizu Corporation, Ulticon Builders, Inc., and Takenaka Civil Engineering & Construction Co., Ltd.
Main use National road with a toll road section
Total size 10.7 kilometers
-Two tunnels (8 meters high, 10 meters wide, 2.3 kilometers long with an excavation cross-section of roughly 80 m2)
-Three bridges (total of 540 meters) and a cut-and-fill road section (total of 7.9 kilometers)
Construction period December 2020 to March 2025

Shoring Plan

As the work involves excavating soft mudstone layers, the excavation process employs a mechanized cutting machine instead of traditional blasting methods. The construction procedure entails the construction of a temporary auxiliary structure known as shoring to prevent the collapse of the excavation wall (ground) with each meter of earth removed. The shoring process starts with spraying concrete onto the excavation wall, followed by the erection of horseshoe-shaped steel shores resembling ribs for tunnel support. Next, wire mesh is installed, and a second layer of concrete is applied. To fortify the shoring, 18 four-meter-long rock bolts (reinforcing bars) are radially driven into the mountain surface.

Davao City Bypass Site

Davao City Bypass Site

The information contained in this news release is the current information on the date of publication. Please be aware that this information may have changed by the time you view it. Please contact the company to inquire for further details.