Surveying the site

When building villas by the thousand, the most efficient method of doing things is always the most cost efficient.

Think of new housing in the UAE and what are your first thoughts? Chances are you are thinking of giant tower blocks, thirty-stories plus.

However, not everybody wants to live in a high rise. There is still a demand for more traditional style villas, with walkable streets and shady willow trees overhanging. There is also the important point that in such communities, independent traders can be allowed to thrive, children can walk to school and life is generally comfortable and settled - a community in other words.

The downside of such living is that many old-style villas are wearing out, and have few of the efficiencies and conveniences expected for today's lifestyles. Happily, several developers have cottoned on to this and are building traditional villas, with a modern twist.

One such project is the Al Reef development, near to the Al Raha beach in Abu Dhabi. When complete, the complex will comprise of a couple of thousand villas, some medium-rise apartment blocks and a panoply of schools and shops, each built in the style of a different architectural style or ‘theme', be it traditional Arabic, desert or contemporary for example. Each has modern cooling, an abundance of plumbing and some will have a pool.

Building one or two low rise villas presents few problems for any contractor. However, when they number in the thousands, becoming effectively a small town any efficiency gained in construction can be extremely valuable in terms of time and money.

Precast

As all the villas are made of precast concrete, effectively a kit of parts, it makes sense to batch concrete onsite. The lead contractor Fibrex does just this, with a pair of batching plant onsite. We didn't get a chance to inspect this installation during our visit, but it appears to have two medium to high capacity plants. What sets this development apart, though is a precast factory owned and operated by the contractor adjacent to the concrete plant.

Steel

Efficiency is further increased by the foundation of a small steelworks onsite. This will be used for rolling and forming joists and so on for use in the project. Using this will help avoid the various peaks and troughs in demand and supply that were seen last summer, meaning the budget for the project will be easier to keep to schedule.

Surveying

The most clever part of this project, though is the way the surveying equipment works.

Regular villa construction is most closely associated with the traditional method of the surveyor using a theodolite to measure distance and angles. This took time, and the data needed to be recorded manually. The last few years, particularly as projects have got bigger, have seen a shift away from this type of technology and on to what are known as ‘total stations'.

These devices can read the horizontal and vertical circles electronically. Understanding how these new machines work exactly is something only an engineer would be able to explain, but suffice it to say they don't rely on bands of light seen through prisms, rather digital imaging technology takes over.

The newest technology to be embraced by the region is satellite positioning. This technology can incorporate distance, direction and difference in height between survey points. A satellite-based surveying system is simply using an electronic distance measurer that does not need direct line of sight between survey points. Instead, a GPS receiver needs to have a direct line of sight to a sufficient number of satellites.

Although the term ‘GPS' is used as a sort of generic trademark to describe satellites in orbit, it actually refers to a ring of devices put in space by the Americans, and allowed to be free for civilian use. In fact, any brand of surveying equipment could equally be using the Russian GLONASS system, or the soon to be launched European Galileo network, which counts Saudi Arabia among its backers.

Fibrex have chosen to buy its surveying equipment from Japanese company Topcon. Eng. Ibrahim pointed out that the company had been impressed with the technology after a demonstration.

"About two and a half years ago, Topcon showed us a machine - a 752 - and we thought it had very good speed and efficiency" he explained. Since then, the firm have invested heavily in the equipment, having bought a hyper GA base station, two rovers and eight 760-series total stations along with five laser levels.

As the site is in Abu Dhabi, Fibrex opted to have its own base station. Other sites in Dubai though can take advantage of centrally located base stations. Topcon's Talal Hanna explained; ‘In Dubai we have what we call reference stations, which means that the municipality is handling these ones. What you have to do is to subscribe and you get the correction through your phone card.'

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