Shanghai Zhenhua Port Machinery Co. Ltd., after all, was a manufacturer of giant cranes for container ports.
The California Department of Transportation agreed to contract the company known as ZPMC in 2006 because it had established a reputation as fast and cost-effective, offering savings of about $250 million compared to the competing bidder.
The new Bay Bridge suspension span. Part of the new $6.5 billion structure, the suspension span, despite its innovative design, experienced construction problems that raised doubts about its durability. These include suspect concrete in the tower foundation, broken anchor bolts, rust on the main cable, and cracked roadway welds.
Caltrans’ decision to hire an inexperienced Chinese company, unaccustomed to the rigor of American construction rules, to fabricate the suspension span’s signature tower and roadway partly explains why costs ballooned to $6.5 billion and misgivings persist about the quality of the bridge. Caltrans continued to bet on ZPMC by relaxing U.S. standards when the firm couldn’t finish fast enough.
China has a difficult bridge to make over the Yangtze, they pick China Railway Major Bridge Engineering Group who have built over 1600 bridges
The Yangtze River is crucial to China it also provides a transportation challenge for travellers to cross its waters. In years past this was achieved using ferries where the river was at its widest but with China’s vehicle numbers growing fast the need to span the river has grown enormously, particularly downstream where China’s economic activity remains focussed. Many bridges have been built to carry motor vehicles (as well as trains) and at present there are 65 spanning the Yangtze River, with another 19 bridges under construction.
The new Yingwuzhou Bridge will play a vital role in the continuing economic development of Wuhan and Hubei Province as a whole. The total cost of the bridge is around US$651 million (RMB 4 billion) and it is taking some 30 months to construct. Ten times less money than the Bay bridge for a longer bridge and the Bay Bridge took over four times longer.
Building this structure has provided major engineering challenges as the area has suffered from earthquakes in the past, with the massive Wenchuan Earthquake having caused major damage in the city (although the landmark First bridge was not affected). With the river’s narrowest crossing points in the Wuhan area already spanned by existing bridges, the new structure is being constructed at a wider point and measures 7.8km, while its main central section is 2.1km long.
China’s premier bridge construction company was brought in as main contractor. China Railway Major Bridge Engineering Group has a long history of building bridges in the country, including a number of other challenging projects and the firm currently has 15 bridges under construction over the Yangtze River. The company has extensive experience and has been involved in the projects for virtually all of China’s landmark bridges. In all the firm has designed and constructed over 1,600 bridges, more than any other contractor in the world, and which stretch for a total of 1,600km.
The Yingwuzhou Bridge will be a three-tower suspension bridge configuration, with four-spans in all. The main spans are both 850m long and the bridge deck carries four lanes of traffic in either direction, with vehicles being allowed to drive at speeds of up to 60km/h once it is opened. This design has called for an innovative engineering approach and to balance out the loads from the two central spans, the main central tower has been constructed so as to offer a degree of elasticity.
To achieve this, the central tower features a novel composite steel-concrete construction that allows a certain amount of flex while also providing sufficient rigidity. It is worth noting too that the bridge structure has also been designed so as to cope with the massive additional loads resulting from earthquakes, given the risk from major tremors in the Wuhan area.
The 152m high central tower is constructed on a foundation that features no less than 39 bored piles, each 2.8m in diameter. The pile cap is oval in shape and measures 70×34m across and 6.5m thick. The bottom 45m section of this column is of concrete construction while the upper 107m of the tower is of steel. The heaviest single segment for the tower weighs 392.7tonnes and placing this required very heavy lifting gear, with a 1000tonne capacity floating crane being used for erection.