The three tunnel options will involve construction costs of between $20 billion and $28 billion and annual recurrent costs of $110 million to $125 million. The tunnel would require 15 hectares to 18.5 hectares of reclamation.

Recreational features including a promenade linking Central and North Point, a green leisure zone, and a waterfront cultural district have been included in all three versions of tunnel option.

Compared with the three tunnel options, the flyover is cheapest, costing only $11 billon to build and $75 million per year in recurrent costs. It also involves the least amount of land reclamation - 11.5 hectares.

However, the consultants concluded that the flyover would have the biggest impact, not only visually but also by imposing constraints on potential harbourfront development. No recommendation was made as to which model the government should adopt.

The report also concluded that the approaches requiring no reclamation were not feasible because of the constraints of existing buildings and infrastructure. A deep tunnel option was also ruled out because it was not technically feasible.

Legislator Kwok Ka-ki said the government had yet to convince the Legislative Council on any of the proposals. 'The government has to provide scientific data to prove that there is no alternative to reclamation,' he said.

The area of reclamation ranged from 10 hectares for the flyover option to 25 hectares for the road option, according to proposed figures released in January last year. The figures have since been trimmed down following opposition from harbour protection groups.

The report will be discussed by the Harbourfront Enhancement Committee, under the Planning Department, next week.