A change of main contractor means that construction work has resumed on the Sheikh Zayed Bridge and it looks as though the end is finally in sight for one of the capital’s most demanding engineering projects.

Written by Jon Muller

Work first began on the structure in late 2003 with an initial completion date set for 2006. This was later extended to 2009 as the builder experienced problems with the unique design and construction of the bridge, which has been labelled by engineers at High Point-Rendel Consultants as “the most difficult bridge ever built.”

Six Construct, a subsidiary of Belgium’s Besix Group, has taken over from Archirodon Construction, the Greek company previously in charge of the project, and now predict that the main gateway bridge to Abu Dhabi island will be open for traffic in October (to coincide with the opening of Salam Street) with a final completion date and opening ceremony scheduled or mid 2011.

Six Construct is also working on a number of other major contracts in Abu Dhabi including the Cleveland Clinic, the proposed VIP guest terminal at Abu Dhabi Airport and ADNOC’s new headquarters, which will be the tallest building on the Corniche at 340 metres high.

Inspired by the sweeping dunes of the country’s deserts, the stunning triple-arched bridge was designed by renowned Iraqi architect Zaha Hadid, the first female recipient of the Pritzker Architecture Prize in 2004, and features a unique fusion of conventional bridge types – incorporating elements of both suspension and arch bridges.

Initially consisting of four lanes, two shoulders and a pedestrian footpath in each direction, the bridge has been constructed in such a way that it can be expanded to six lanes in each direction, should the flow of traffic require it, simply by repainting the dividing lines.

The unusual combination of concrete and steel has also provided more than its fair share of headaches. The three hollow steel arches are so large and complex that they had to be manufactured in Thailand before being shipped over – the two smaller arches are made out of a single piece of steel, while the large arch is a two-piece welded design. The arches were so heavy and unwieldy that the crane had to be specially modified just to lift them into place.

“It is certainly not a standard bridge design,” explained Henrik Andersen, project manager for COWI, the consultancy firm hired by the Works Department of Abu Dhabi to independently check that the bridge fulfils the design requirements. “The advanced geometry of the steel arches and the solid concrete pillars made it necessary to develop a highly detailed computer model of the bridge in order to determine is behaviour.”

The bridge, which can carry up to 1,600 cars at any one time, has been designed to withstand twice the traffic loads prescribed by the American Association of State Highways and Transport Officials (AASHTO). It has also been equipped with Seismic restraining devices and absorption dampers to make it capable of withstanding a Zone Two earthquake even though the UAE is only classified as a Zone One country – Iran is the closest Zone Two country.

Once completed, the landmark bridge will provide unparalleled views of the Sheikh Zayed Mosque and the city’s skyline, while the Abu Dhabi Municipality have estimated that journey times into and out of the city will be reduced by about 15 minutes. ADM has also predicated that by the time it is finished the cost of the bridge will have exceeded AED 1 billion.

Sheikh Zayed Bridge: facts and figures

* Complete length: 842 metres
* Highest point of main arch: 63 metres
* Width of bridge: 61 metres
* Vertical clearance under bridge: 17 metres
* 666 bored piles make up the foundations with a total length of 15 km
* Over 200,000 cubic metres of concrete has been used – the central pier alone contains enough concrete to   cover a football pitch to a height of five metres
* 52,000 tonnes of steel was required for the structure and reinforcing
* The bridge has a capacity of 1,600 cars – coincidentally the same number as the amount of workers currently employed on the project
* The bridge has been designed with a 120 year life expectancy