Secretary for Transport and Logistics Mable Chan on Friday said construction cost for the South Island Line (West) is expected to be 40 percent less than first thought.

Rather than a heavy rail system proposed earlier, officials said they plan to build a "smart and green" mass transit system using viaducts, along with a tunnel through the hilly terrain between Queen Mary Hospital and the University of Hong Kong, according to a paper submitted to Legco earlier this week.

The proposed transit line will span about 7.5 kilometres and link HKU and Wong Chuk Hang MTR stations. Officials hope to start the planning and design process next year, with construction set to begin in 2027.

At a Legco subcommittee meeting, lawmakers generally expressed support for the project, saying it has been a longstanding priority for Southern District residents.

Chan said the government opted for the smart and green model after taking into consideration issues such as technical capabilities and financing.

The transport minister said the new plan could be much cheaper than the original one.

On the potential visual impact and noise issues for residents, Chan said authorities would seek residents' feedback before construction work begins.

“As far as visual impact and noise are concerned, if we are using the smart and green mass transit system with rubber wheels, the noise levels generated will be less than for heavy rail systems, and it will take up less space,” she said.

Principal Government Engineer Eddie Leung said he believes the new transit line will be able to cater to the needs of Southern District.

Officials have said it will serve 130,000 residents and 50,000 people working there.

As for a new mass transit system for Kai Tak, Chan said the objective is to award the contract in 2026 and have it completed within three years after construction starts.