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How Cleveland bridged the mighty Yangste

Site Report

Kvaerner Cleveland Bridge has a wealth of experience working in different countries with team members drawn from mix of cultures. But there were still lessons to be learned on the Jiang Yin bridge. Adrian Greeman reports from China

THE JIANG YIN suspension bridge, China's biggest and the world's fourth longest, was always going to be a challenge. But for Kvaerner Cleveland Bridge it almost became a nightmare.

Halfway through building the 1,385-m main span last year the young management team thought it might never finish.

Battling back onto programme has been a major triumph, not only in engineering and management, but also in cross-cultural relations, technology transfer and team-building.

The bridge is a prestige project which must be ready for October, when the country celebrates the 50th anniversary of the Chinese Revolution. President Jiang Zeming himself will cut the ribbon opening the three-lane dual motorway crossing.

Jiang Yin will be the first major crossing of the Yangtse river on the western side of China. Some 200 km upstream of Shanghai, it will carry a main north-south highway link.

The cost of Cleveland's superstructure is $160 million (£100 million) which includes £55 million of international development aid from the UK, linked to the purchase of British goods.

The main span being built by Cleveland is a suspension bridge with steel deck box units. The side spans are supported on viaducts and are being built by Chinese contractors.

The concrete foundations, anchorages and 196 m-high towers for the suspension span were also built by local firms.

Cleveland arrived on site in September 1997 to start saddle installation in November, having just built the huge Tsing Ma crossing in Hong Kong. Jiang Yin, with its 18,000-tonne deck, must have seemed quite small, compared with the 40,000-tonne Tsing Ma.

Cleveland had an extremely tight programme. The British firm's superstructure contract has just under two years on site.

The whole bridge is being built in five years.

Work did not get off to a particularly promising start, with the delayed handover of one tower and a slow first few months from Cleveland's subcontractor, Shanghai Foundations.

But project manager David Climie was undaunted.

'I thought we could make it up fairly easily in the cable hauling,' he says.

And Shanghai Foundations did well stringing the first winch wires across the extremely busy, 1.5 km-wide Yangtse river, a feat watched by thousands of local residents.

But, while the walkway erection went relatively well, cable work and deck installation did not.

Deputy project manager Raj Soni estimates that less than 50 per cent of cable work was done in the first three months.

'In the last month they did all the rest,' he recalls. Bill Hawkins, the manager of the deck assembly yard, tells a similar story about the 450-tonne deck box units: 'We made eight units in five months and the next 36 in six-and-a-half months.'

Tensions developed between the British contractor and the Chinese engineer and subcontractors.

Cleveland, used to European precision in project management and timing, found that the three Chinese firms organised in a looser fashion. The firm found it difficult to put its own experience across, particularly on questions of safety and quality.

The Chinese expressed feelings that procedure was too slow and complex. And they could not understand some of the safety practices on which Cleveland insisted.

For example, the daily untying and retying of the tower-to-tower walkway from the cable in order to measure the fit of the new wires in the cool of the night was considered excessive.

Mr Soni protests: 'You cannot take chances on a 20-tonne cable strand breaking loose in the sudden high winds you can get here. You would lose more time, or lives, even.'

But for the Chinese contractors, it was galling to be instructed in new ways of doing things they had done many times before.

Charles Slater, of consultant Mott McDonald, which advised on the superstructure, says the expatriates were at times perhaps too impatient, even if they were often right. Mr Climie agrees, adding that the Cleveland team had to learn not to box people in by insisting they knew the right answer to any particular problem.

'That was the way not to get what you wanted,' he says. 'And besides, we did not always know the right answer, either.'

Cleveland also experienced problems arising from the distance of its own design team from the complex temporary works. It arranged a satellite link with a head office design team in Darlington, but this added to delays in the early stages because responses and decisions were not made as quickly as they might have been had the team been on site.

Some of that team came out to China in spring last year, increasing Cleveland's on-site presence to more than 65.

This move pleased Zhou Shi Zhong, senior civil engineer with the Jiangsu Yangste Bridge Construction Comman- ding Department, which is co-ordinating the design and supervising construction.

Mr Zhou had been frustrated early on that there was 'too little authority on site' to push decisions through.

There were also technical challenges to overcome.

'Cleveland lacked experience with pre-formed parallel wire strand,' comments Mr Zhou.

Cleveland has wide experience in suspension work but always with wire- by-wire aerial spinning. Here the engineer wanted a different method - preformed parallel wire strand - feeling that this route would give better precision and speed. The strands used are factory-made bundles of 127 galvanised wires, some supplied by UK firm Bridon and the rest by two Chinese firms.

Some 185 strands, each double the span length, had to be hauled across and back using winches and rollers on the walkway.

Cleveland encountered problems at first with tension.

'We took advice from Shanghai Pujiang, the maker of the strand, on how tight to roll them onto their 50-tonne drums,' says Mr Climie. 'In retrospect, we should have gone for a higher tension.'

Strand ends came loose during unrolling, causing a spaghetti-like mess of wires to fly around the winches.

Cleveland engineer Dave Gill developed a method on site to increase the tension.

Management and communications problems were overcome by compromise from both British and Chinese sides, which Mr Climie feels helped eventually to forge a team spirit. For example, Cleveland joined in the Chinese-style weekly discussion meetings.

And Mr Zhou found a solution to the slow progress on the job. He called in the subcontractors for special meetings, from which emerged a bonus incentive system for the number of strands pulled across the river.

This had a miraculous effect. From a few strands a week the rate jumped to four strands a day.

'We even had to slow them up in order to keep a check on quality,' says Mr Soni.

The quality achieved is impressive. The void ratio of the cable - the amount of air space left after hydraulic compaction - is a meagre 16.5 per cent. Normal preformed cable comes in at about 18 per cent.

There were other tribulations for the team, not least to do with the weather. Last year's devastating floods of the Yangste could have put the lid on everything. Shipping was stopped for two months during the floods to prevent damage to dykes.

This created a potentially devastating problem because although most of the deck steel came from Darlington, some difficult-to-transport corners were subcontracted to Wuchang Shipyard, based in Wuhan, 500 km upstream of the bridge.

Fortunately, Cleveland's current stockpile of corner units was just sufficient.

Things have accelerated since then. Deck lifting, using cable mounted gantries from Denmark's Storebaelt, has gone well. Streamlined steel box units measuring

32-m long by 326-m wide have been positioned at the rate of one a day since February, despite temperatures that dropped to -20 deg C at times.

Deck lifts finished in April and welding became the crucial operation. This could not start until 20 units had been hung and the cable sag had flattened out sufficiently. Welding finished in mid-May and road surfacing has now begun.

The whole job should now be complete by late August, ahead of the original October date, allowing the client time to rehearse the official opening.

'But we still have to keep the pressure on,' says a weary, yet more relaxed, Mr Climie.