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Middle East: Hard drive

The credit crunch may have hit Dubai, but investment is flourishing in another, less well known but promising Emirate. Gemma Goldfingle reports from Fujairah.

Fujairah is the fifth largest of the United Arab Emirates (UAE) and is seen as the next growth hot spot in the region. Already a busy port, Fujairah will become a bustling trading centre for Abu Dhabi’s oil barons and Dubai’s financial and industrial sectors.

The area is also expected to follow in Dubai’s footsteps and emerge as a popular tourist destination.

Fujairah is the only Emirate that is almost totally mountainous and roads in the region are limited to basic tracks. The desolate, rugged terrain makes construction in these parts challenging − a contributing factor to its undeveloped nature.

Dubai-Fujairah map

The beginnings of change

But all that is about to change with the development of a 10-lane, 45km motorway that will wind through the mountains and form part of a link between Fujairah with Dubai. Construction began in August 2006 and is due for completion in late 2010.

“This is one of the first projects set in these steep mountains,” says main contractor, Greek-Cypriot firm National Wheel J&P (WJ&P) project manager Pantelis Christou.

“Creating the route involves major cutting and filling of the huge mountains − over 14M.m³ of material had to be excavated.”

To make the £202M route viable, the severe gradients of the mountains had to be evened out.

“Creating the route involves major cutting and filling of the huge mountains − over 14M.m³ of material had to be excavated.”

Pantelis Christou, National Wheel J&P

Intense rainfall, which occurs about once a year, has formed deep gullies in the terrain. It would be too costly to build bridges to pass these valleys, so the contractor explored the use of massive earth-retaining structures to support embankments which carry the road across the gullies.

Geosynthetics specialist Tensar was commissioned to design a number of soil-reinforced walls for the project, the highest being 60m tall.

Built in three tiers reaching 20m, spreading along a 50m length of road, Tensar’s wall is one of the largest reinforced earth-retaining structures in the world.

Drawing on experience

WJ&P drew on experience from another road building project in nearby Dibba, in which similar retaining walls were constructed.

“Dibba Road was the first piece of infrastructure through mountains in the Emirates. On that project we used geogrids − made from a stiff polymer material that fits between manufactured concrete blocks. This material distributes the load and retains the earth. However, this solution had not been used on structural walls this high,” says Christou.

To create the walls, rock, known as Gabbro, which is removed from the mountains to form cuttings, has been used as fill. This is crushed, compacted, then reinforced with uniaxial geogrids. The geogrids are a mesh made from high-density polyethylene material that is stretched in one direction during manufacture to produce a high strength geogrid roll.

“We used geogrids − made from a stiff polymer material that fits between manufactured concrete blocks. However, this solution had not been used before on structural walls this high.”

Pantelis Christou, National Wheel J&P

The geogrids are sandwiched between 200mm wide, 200mm deep, 400mm long interlocking modular concrete blocks. The blocks are laid dry without using mortar, removing the need for water-based products. Fill is placed and compacted to 200mm thickness. A layer of geogrid then goes on top and the process then restarts, so that the wall is built up.

Each layer of fill is tested to ensure that 95% or better compaction is achieved. Over 25 geogrid-reinforced walls are being installed along the route, amounting to a total of 100,000m² of wall facing. This has required over 2.5M.m³ of fill.

Flood risk

Fujairah road

4m wide box culverts

Despite its location in the arid conditions of the UAE, the rugged ravines of Fujairah are susceptible to flooding.

Although downpours are rare in the Emirates, the consequences can be disastrous. Fast-flowing water rushes down the steep slopes and can wipe out entire villages.

With one flood occurring in Fujairah every 20 years, the 45km road had to be designed with “the worst case scenario” in mind, says W J&P project manager Pantelis Christou.

Pipe culverts will be incorporated below the road surface and in seven sections of mountain, 4m wide box culverts have been installed to divert any rainwater.

In the retaining wall that bridges the steepest ravine, four, 4m wide concrete box culverts are connected, creating a drainage route that runs 16m through reinforced soil-retaining walls.

 

The Gabbro rock is harder than granite which proved too strong for excavators to cut through. An intensive blasting operation, supervised by police officials, was necessary to remove over 9M.m³ of material.

The excavated material is crushed and graded to ensure it can be compacted to the requisite level. As well as minimising cost of material, the reuse of excavated site-won material also cut carbon emissions by reducing transport to and from site.

“We have proved that development is possible in what were previously thought to be unworkable areas. Our solution has been quick and economical.”

Pantelis Christou, National Wheel J&P

“It is a massive logistical challenge, but we have planned the construction of the cut and fill sections so we can simultaneously excavate materials from one site and reuse it immediately on the nearest fill section. This minimises the transfer of materials along the 45km site,” says Christou.

When the cut and fill sections are complete, surfacing works are carried out. For this, wet mix aggregate material is compacted to between 98% and 100% to create the base level, finished off with hot mix asphalt surfacing.

“This is a prestigious project in the Middle East. We have proved that development is possible in what were previously thought to be unworkable areas. Our solution has been quick and economical, without the construction of many tunnels and bridges to form the route in the mountainous regions,” says Christou. Between 100m² and 150m² of wall is being completed per day.

With less than 18 months before handover to the Ministry of Public Works, over 60% of the route has been finished.

Who’s who

  • Client: Ministry of Public Works, United Arab Emirates
  • Contractor: National Wheel J&P (WJ&P)
  • Consultant: Wilbur Smith Associates
  • Supervising consultant: Dorsch Consultant
  • Geogrid designer and supplier: Tensar International
  • Project value: £202M

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