Back in 1990, when improvements to the Al Garhoud road to the east of Dubai city centre were first considered, much of the land along the dual carriageway was still empty desert.
Eight years later, as main contractor Almullah puts the finishing touches to the pounds14M Beniyas interchange, the road is fringed by commercial developments, including one of the region's largest shopping malls. The pace of change makes design and planning extremely challenging. But, with the road forming an important inter-Emirates route as well as linking Dubai International Airport with the Al Garhoud bridge across Dubai Creek, it was obvious that improvements were needed.
'Originally the junctions at Beniyas and Al Garhoud to the south were simple T-junctions controlled by traffic lights,' explains Hyder resident manager Kevin Jones. 'However, the latest traffic forecasts peak time flows of 8,000 vehicles an hour both ways through Beniyas by 2011. Only sophisticated grade-separated junctions could cope with that level of traffic.'
The pounds18.6M Al Garhoud interchange, which opened in spring last year, went out to tender with two fewer access loops than were finally built. Extra loops were added to cope with traffic generated by developments proposed for the surrounding area.
Much the same happened at Beniyas, due to the development of the giant Deira City Centre shopping mall and office complex alongside. Here developer Majid Al Futtaim Group funded the construction of an extra exit ramp from the planned interchange, to provide a better access from the main road into the development.
Upgrading urban motorways anywhere in the world usually involves diverting a multitude of services. Dubai is no exception. From the contractor's point of view the most troublesome, especially at Al Gahoud, were ageing oil-filled 132kV cables running alongside the road. These also caused major problems for the underpass at Beniyas.
Even though this latest interchange is concentrated into a much smaller area, it has more existing services to contend with. As well as the high voltage cables, the main stormwater outlet from the airport crosses the site. And three parallel 800mm diameter irrigation pipes feeding the lush green fairways of the nearby Dubai Creek golf course had to be kept in operation throughout.
Extensive landscaping featuring non-stop irrigation with treated sewage is one of the main features which distinguish motorway structures in Dubai from their equivalents in rainier climates. Some 25ha of landscaping were designed by Dubai Municipality engineers for Al Gahoud, watered - and fed - by 80km of irrigation pipes between 300mm and 80mm diameter.
Landscaping of the smaller Beniyas complex will begin soon. Other obvious visual differences include much 'curvier' cross-sections for bridge and flyover decks - and the fact that every square millimetre of exposed concrete receives a protective coat of an acrylic-based paint.
Apart from the cosmetic benefits, Jones says use of the coating is based on long term experience with the aggressive atmosphere of the Gulf states. 'The air is full of salt, and unprotected concrete has a hard time,' Jones explains. 'There's a corrosion-monitoring system built into all the main structures, which can be converted into cathodic protection if it detects chloride-induced corrosion beginning.'