Environmentalists' concerns over the impact of the Central-Wan Chai bypass have kept the project on the drawing board for more than a decade.
The government saw the HK$20 billion road, which would run along the harbour, as a solution to traffic congestion between Causeway Bay and Central, where some roads are carrying 20 per cent more traffic than their design capacity.
A transport study estimated journey times between the two spots would lengthen from 15 minutes to 45 minutes by 2016 without the bypass.
The government said the 4km highway was a prerequisite for electronic road pricing, under which road users are charged a levy when they enter a busy area. Many experts believe road pricing would help control traffic, but the government said road users had to be offered an alternative to such thoroughfares as Connaught Road Central, Harcourt Road and Gloucester Road.
The bypass, originally scheduled to be built by 2010, was repeatedly stalled by environmentalists' suits.
The High Court ruled in 2003 that harbour reclamation could only take place if an overriding public need were proved. The government has since cut the size of the temporary reclamation required for the bypass and held many consultations. Work may begin next year.