However, the Guangzhou-Shenzhen-Hong Kong express rail link and the much-touted bridge project remain up in the air.

The significance of the infrastructure projects in increasing the cross-border flow of people and goods has prompted Chief Executive Donald Tsang Yam-kuen to call for more rapid progress.

He made the appeal while attending the Pan-Pearl River Delta Co-operation and Development Forum in Sichuan in July.

Academic Zheng Tianxiang, of Zhongshan University, Guangzhou, who is an adviser to the Guangdong government, said the sooner the corridor was completed, the better for the delta's economic and environmental prospects.

'The corridor plays a vital role in boosting cargo flow between Hong Kong and Shenzhen, as trucks can bypass the crowded and polluted Shenzhen city centre to the Huanggang checkpoint,' he said.

Designed to ease heavy traffic at the checkpoints of Lok Ma Chau, Sha Tau Kok and Man Kam To, the corridor will also help spur cross-border development of financial services, logistics and tourism in the delta.

Linking Shekou in western Shenzhen and Deep Bay in the New Territories, the Western Corridor has been under construction since 2003 in a joint development between the Shenzhen and Hong Kong governments, with the Hong Kong section costing about $3.6 billion.

A Hong Kong government spokeswoman said the construction of the bridge section of the corridor was expected to be completed on time at the end of the year, but conceded there were some delays to the piling work on land reclaimed for a passenger terminal.

'The corridor will be available for traffic as soon as the terminal is ready, which is expected to be at the end of next year,' she said.

Hong Kong's Security Bureau last month awarded the $320 million construction contract for the terminal, which will be in Hong Kong waters and will house customs and immigration services for the mainland and Hong Kong.

Meanwhile, concerns about delays and soaring costs loom large over the 49km bridge project planned to link Hong Kong, Zhuhai and Macau.

The three governments have yet to reach consensus on the design of the bridge and tunnel, and neither Macau nor Zhuhai are reportedly willing to invest in the project.

The undertaking still awaits a green light from the State Council.

Professor Zheng said the bridge was now likely to cost between 60 billion yuan and 65 billion yuan - almost double the original estimate of 30 billion yuan.

He said most of the extra costs would be in the construction of three artificial islands that will link a 29km tunnel with the 20km bridge.

This has prompted questions about the financial viability of the bridge.

'The higher the construction cost, the higher the toll fees and the higher the risk of its financial viability,' he said. 'I fear the project may become a white elephant.'

The consensus alignment means the bridge will start from the east bank of San Shek Wan on north-western Lantau, cross the Pearl River estuary via a combination of bridge and tunnel, connecting with an artificial island near Macau's A Perola and Gongbei in Zhuhai.

The financing of the bridge was expected to be shared between the three city governments, as the bridge would pass through all three cities. But there has been no final decision on the financial arrangement.

However, private investors have expressed keen interest in taking a slice of the project, with Sir Gordon Wu Ying-sheung, chairman of Hopewell Highway Infrastructure, its most enthusiastic backer.

Sir Gordon, who has promoted the bridge project for almost 20 years, is in talks with Hopewell's mainland partner, Guangdong Provincial Highway Construction, and developers Sun Hung Kai Properties and Shun Tak Holdings, to form an alliance to vie for the project.

Hopewell has even built up its reserves for the project, with cash on hand of $2.44 billion, and earlier this month it boosted its cash resources by arranging more than $3.5 billion in syndication loans.

However, the governments involved have yet to publish a time frame for the tendering process.

'We are waiting to throw in bids, and hope the tendering will be available as soon as possible,' said Hopewell Highway Infrastructure managing director Thomas Jefferson Wu, Sir Gordon's son.

The Guangzhou-Shenzhen-Hong Kong express rail link, a rail shortcut between Guangzhou and Hong Kong, also languishes on the drawing board.

Despite several rounds of meetings last month between the Guangzhou, Shenzhen and Hong Kong governments, only the mainland section of the rail route has been finalised.

With two stops at Shibi town, Guangzhou and Longhua town, Shenzhen, the Hong Kong section is pending a decision from the Hong Kong government. A spokeswoman said a proposal by the Kowloon-Canton Railway Corp was under review.

The proposal was based on using the corporation's underused West Rail line (running between Tuen Mun via Tin Shui Wai and Nam Cheong) and ending the express rail link at the proposed West Kowloon cultural hub.

There is no urgency, but the rail project would be a speedy alternative between Guangzhou and Hong Kong. The express rail link will cut travel time to 60 minutes from 100 minutes.

'The express rail line can be positioned as a mass carrier for passengers, whereas the KCRC's existing through-train services can focus on cargo and logistics transport,' Professor Zheng said.

For effective Pearl River Delta integration to become a reality, the governments concerned will have to overcome the roadblocks in the region's transport infrastructure.