When Al-Rosan was tasked with building a 256km road through the Rub’ al Khali desert, they knew it would be a demanding project
While the Kingdom of Saudi Arabia shares a 600km border with the Sultanate of Oman, at present there is no direct land route between the two countries. Road freight and travellers must take a circuitous route via the UAE. That’s set to change when a major land bridge linking the two countries opens later this year. The Saudi-Oman border port – as it is known – includes 565km of road in the Empty Quarter on the Saudi side, and 160km in Oman. The new route will shorten the current road trip by 400km, reducing transport costs for freight and passengers and boosting tourism.
But there’s a good reason why there’s been no land route: in the south of the Arabian Peninsula lies the Rub’ al Khali desert (or Empty Quarter), the largest sand desert in the world. With temperatures reaching 50 degrees Celsius or even higher during the day and plummeting to 1 degree during the night, as well as harsh winds constantly blowing sand, it’s a difficult area for construction work. But while the Empty Quarter is the stuff of legends, even a desert is not impervious to the steady march of progress: the Shaybah oil field is a major production site for Aramco, with numerous rigs, living quarters and machines working, and with over 400km of pipeline within the desert itself.
So when Saudi contracting company Al-Rosan Contracting won a contract to build the 256km stretch of highway through the desert and to the Oman border, they knew it would be difficult but not impossible. The company invested significantly in new equipment to take on the project, with the final fleet made up of a considerable number of Volvo Construction Equipment machines, 95 in total, including 68 articulated haulers (35F models) and 10 of the large EC700C hydraulic excavators, used for quarrying out dunes.
Fahad Hazza Aba Alros, general manager of Al-Rosan Contracting, describes the scale of the difficulties of running a project more than 600km from the nearest inhabited area: “I would say the entire project was a challenge from day one, whether it was the climatic conditions, topography of the area, the distance from the nearest inhabited city or the availability of spare parts and services. None of the usual factors that are associated with success were present in this project.”
The desert terrain consists of tall, wind-blown sand dunes, as high as 150-200 metres, with salt flats or sabkhas (areas where seas have become landlocked and evaporated to form saline deposits) between the dunes. As far as building a road is concerned, the conditions could hardly be worse. The sabkhas have a very low bearing capacity, while the high dunes shift with the wind and any road path cut through them would quickly become inundated by sand.
Engineer Fayez M. Subbaheen, project manager at Al-Rosan Contracting, explains to CMME, via telephone from the remote job site in the southeast of the kingdom, that the solution to this difficult terrain was to build the road over enormous sand bridges that distribute the load over a wide area when travelling across the sabkhas, and allow it to go over high dunes, preventing accumulation of sand on the road.
But to do this required enormous amounts of sand to be excavated and hauled into place: in all, 130 million cubic metres of sand cut and fill are being used. In terms of cubic volume, this is equivalent to more than 50 great Pyramids of giza. The comparison is apt, since the sand bridges were constructed in pyramidal form. Needing to support a finished road width of 24m, at their base they are as much as 500m wide, rising up in 1m lifts; some of the highest embankments have 60 or 70 layers.
The major part of the 234.5km road consists of a single-lane carriageway in each direction, although in sections where there are steep inclines, as it travels over the towering sand dunes, there are climbing lanes for trucks and slower-moving traffic. In addition to the sand, a further 12 million cubic metres of selected material are being used to protect the embankment slopes from erosion from wind and from water.
As Subbaheen describes the scale of the project, it becomes clear why the Volvo CE haulers were so vital.
To build the embankments, sand is quarried from the dunes by excavators, including Volvo’s large EC700Cs. The haulers carry the sand to the construction site, dumping it to make the layers; each articulated truck capable of carrying 22m³ of material. Since the sand is extremely fine, it runs like water and is blown away by a constantly driving wind. Some mornings they return to the work site and find that sand dumped the previous evening, but not yet compacted, has completely disappeared, blown away. The Volvo haulers are also able to travel across the fine sand and up gradients, essential for productivity.
To form the embankments, sand is placed in layers one metre high and then compacted dry, which Subbaheen says is a very efficient method, since it is quick. Wet compaction takes far longer, and water in the Rub’ al Khali is scarce. Heavy 13-tonne self-propelled drum rollers are used for compaction, with double oscillators in the drums for greater compactive force. A short amplitude oscillation for high repetition means faster compaction, allowing them to quickly achieve the relative density required (70%) with six to eight passes.
Once the embankment is built up to the desired height of the road, its side slopes, constructed with a 4:1 or 6:1 slope, are shaped. To prevent erosion from wind or the occasional rainfalls during the wet season (which normally occur as heavy thunderstorms), the slopes are covered in materials. Natural soils consisting of silt and clay, as well as small amounts of marl, are mixed with water and then spread on the embankment wall, again using the Volvo haulers. The silt and clay hold the water and prevent erosion by wind or water.
At the remote job site, Al-Rosan is operating almost independent of the outside world. A residential area was established for the labourers, with some 600 workers including machine operators on the site. For construction of the road layers, Al-Rosan set up complete facilities, including a brand-new asphalt batching plant for the project, able to produce 240t per hour. The contractor established a quarry 400km from the job site, since there is no stone in the desert, from where they haul aggregates. A mobile concrete batching plant is being used for the bridges, culverts and slope protection around the culverts. Precast footing for the lighting columns is also being carried out. “This job is completely independent of any other project,” says Subbaheen.
For Volvo CE dealer Al-Futtaim Auto and Machinery Company (FAMCO), it was obvious that they also needed to establish a full service centre on the site, since providing after sales support from their dealership branch hundreds of kilometres away in Riyadh was out of the question.
“Al-Rosan is one of our important contractors and a loyal customer of Volvo CE,” says FAMCO Saudi managing director Amal Al Mizyen. “When they were awarded this contract, we were left with the challenge of supporting them logistically, as the closest city was nine hours away by road. However, from the very beginning Al-Rosan said on-site support was crucial, and so we had to gear our services up to that challenge. With a distance of 1,000km from the nearest inhabited city, we were determined to rise to the occasion and prove that we are worthy of our reputation.”
This was especially important given the harsh conditions and driving sand that take their toll on machines and operators alike. From its Riyadh branch, FAMCO established a logistics ‘bridge’ to supply the Volvo CE equipment and spare parts to the isolated site, while at the project site they constructed a modular maintenance facility, capable of carrying out preventative maintenance as well as all needed repairs, since transportation of any machines would be costly and time-consuming. In addition to the major workshop, the after sales facility has offices and a parts store, with service vans, technicians and a store keeper on-site.
The on-site workshops run 24/7, and the harsh conditions put equipment under enormous strain. To cope with this, the FAMCO after sales team does routine maintenance and has reduced service intervals on some of the crucial parts, such as engine oil and air filters.
Subbaheen says that the most important contributors to the project’s success have been the Volvo haulers, not only for their ability to traverse the fine sand, but also for their air-conditioned, pressurised cabins that insulate drivers from the heat and sand. “These are very strong machines. Very suitable for the desert and sand area. It was amazing to see the dumpers moving on the very fine sand.” With the air-conditioned cabins on all equipment, the operators were able to work safely without ill-effects from the sun. Work was also halted between 11:30am and 2:30pm due to the midday heat, which can reach 55 degrees during the nine-month summer.
The psychological well-being of the labour force was paramount, says Subbaheen. He explains that it is impossible to imagine the feeling of working on a site where all that is visible is sand, and there is no life or anything else around the project, entirely barren. “you cannot imagine a project in the desert. There are mountains of sand, you are moving on sand, and everything is constructed from sand.”
To make things easier, the housing project had moving camps with prefabricated units for residents, completely isolated from the heat and air-conditioned. Kitchens and bathrooms were supplied, to minimise impact on the natural environment of the desert. leisure options included sports areas and televisions to watch movies, in order to create a social life for the workers.
To call this project the most challenging that Al Rosan has undertaken since it was established in 1976 is perhaps an understatement: the Saudi-Oman Border Port project is one of the most challenging construction projects carried out anywhere in the GCC in recent years. When it is completed, expected to be Q3 2015, it will allow new and closer access between the Kingdom of Saudi Arabia and the Sultanate of Oman.
To prevent blown sand drifting onto the road, the Ministry of Transport will provide 24-hour maintenance groups to remove sand that has accumulated on the top surface of the finished road, to keep it safe for travellers. There are also barriers and sand mitigation walls to prevent sand obstructing the road, keeping the routeopen.
“The road through Rub’ al Khali is a fine example of how service, product support, customer engagement and on-site maintenance all came together for the contractor,” says Paul Floyd, FAMCO group senior managing director. “This is a project that is extremely important to Saudi Arabia’s infrastructure development, and we are extremely proud of being part of this iconic but ambitious project, and rising to the challenge.”