Transport officials on Tuesday said the "smart and green" transport systems in Kwun Tong and Kai Tak will not be completed until 2034 at the earliest.

At a press conference to unveil the city's major transport infrastructure blueprint, transport minister Lam Sai-hung said the government will invite operators to express interest for the projects next year, as authorities work on the design of the two systems.

One of the projects will connect the hillside areas of Kwun Tong to Choi Hung and Yau Tong MTR stations. The other will link the old Kai Tak runway area to Kai Tak Station.

Lam said he expects the seven-kilometre green mass transit system in Kwun Tong and the Kai Tak system will be completed sometime between 2034 and 2038.

"For Kowloon East, the difficulty lies in the fact that the alignment will run along congested residential areas at a hilly terrain. So we need to plan and design the alignment that makes it viable. Viable means that it can be buildable and it will cause the least disturbance to the traffic as well as residents nearby. So we need some time to do the analysis," he said.

Lam also said he hopes the government's plan to build three major roads and three new railways will strengthen connections and improve efficiency.

The three railways are the Central Rail Link between Kam Tin and Kowloon Tong, a southern extension of the Tseung Kwan O Line, and the Hong Kong-Shenzhen Western Rail Link connecting Hung Shui Kiu and Qianhai.

The three roads will be the Northern Metropolis Highway, Sha Tin Bypass and Tseung Kwan O-Yau Tong Tunnel.

The government will also build a tunnel linking Hong Kong Island to Lantau.

But Lam said it is too early to put a price tag on the infrastructure.

"It's a bit premature for us to release the cost estimate for a project that will commence construction probably ten years from now. There are many variables in producing the cost estimate. And I don't think it would be good to have a cost estimate which may not be realistic to reflect the variables involved," he said.

Meanwhile, authorities are putting the MTR's North Island Line on hold, saying the network of existing railway and roads and those being planned can cater to demand until at least 2046.

The government said an upgraded signalling system on the Island Line will increase the railway's capacity, and infrastructures like the Northern Metropolis will make changes to where people live and work.