The project, involving road tunnelling works from Sepanggar port to Universiti Teknologi Mara (UiTM) in Kota Kinabalu, aims to cut the distance between the two points to 7km, compared with the existing route.

Chief Minister Datuk Seri Musa Aman, when launching the hole-through ceremony for the 600m twin tunnel near the port on 20 May, said while tunnels are more expensive compared with clearing hills to build roads, they are more financially viable because of lower long-term maintenance.

"This is not something new in Malaysia, but the use of this technology in Sabah is a meaningful starting point for the construction sector.

"I congratulate the state Infrastructure Development Ministry, including the Public Works Department (PWD), which is one of its agencies.

"It is also an environmentally friendly approach, as it does not affect natural structures on the ground.

"We will consider this approach for other hilly areas in the state, in line with the nation’s emphasis on green technology," said Musa.

Deputy Chief Minister Tan Sri Joseph Pairin Kitingan, who is also state infrastructure development minister, proposed that tunnelling could be used to connect the hilly areas of Tamparuli-Ranau, Beaufort-Keningau and Moyog-Tambunan.

Sabah PWD director Datuk John Anthony said the twin tunnel is 73 per cent complete and expected to be opened to public on 15 April next year. Construction of the tunnels began in July last year.