The tunnels will prevent a large portion of Bukit Batu Lanchang, which separates Lebuhraya Thean Teik and the larger Island Glades, from being levelled.

The tunnels and viaducts, which are not included in the original plan, are also environmentally friendly, chief minister Chow Kon Yeow said after a site visit today.

“If no tunnels are used, we will have to cut the hills and this will have a major environmental impact,” he said.

Work on the project began last February but has progressed only 8% as of Nov 30 because of delays related to land acquisition and the intermittent movement control orders. It is slated for completion in January 2025.

Razif Ahmad Zuber Ahmad Khan, the project director with Consortium Zenith Construction Sdn Bhd (CZCSB), which is undertaking the project, said the three twin tunnels would be bored using the drill-and-blast method, moving 3m per blast.

He said each tunnel would be a dual carriageway in a single direction, and vary in length because of the curving route and geographical factors.

Razif said six viaducts would connect the tunnels at their ends, as the twin tunnels were split into three sections. Traffic would be subjected to a 70kph speed limit.

The bypass road will have four interchanges – at Lebuhraya Thean Teik, Jalan Bukit Gambier, Jalan Sultan Azlan Shah and the Tun Dr Lim Chong Eu Expressway (George Town-bound).

It is the first of two projects to employ tunnels, with the other being the Pan Island Link 1 (PIL1) highway, which has been approved but has yet to take off.