x Abu Dhabi, UAEThursday 27 July 2017

Etihad Railway plans for shifting sands

Desert terrain presents unique problems for trains, but Etihad Rail engineers are using a mix of international and Bedouin know-how to ensure the 1,200km track across the country can deal with the dunes.

The locomotives are 22.6 metres long, five metres high and weigh 187 tonnes. Courtesy Etihad Rail
The locomotives are 22.6 metres long, five metres high and weigh 187 tonnes. Courtesy Etihad Rail

ABU DHABI // For centuries the Liwa Oasis provided sanctuary for the Bedouin people.

Now it will provide sanctuary for the nation's trains.

When construction begins on the first leg of the 1,200-kilometre Etihad railway, months of work will already have gone into research to conquer the one thing that can stop an Arabian train in its tracks: sand.

Engineers can carve tunnels through mountains but the fight against sand is fought on shifting battle lines. Though sand can be so light that it floats on air, it is the impermanence of the shifting dunes that gives them the strength to halt a train moving at 200kph.

"It's not the enemy of the train, but the nature of the UAE's desert topography and sand movement could become an obstruction," said Shadi Malak, the commercial executive director of Etihad Rail. "It's very important before we build the trains that we learn from other nations that have gone through this experience and have come across these challenges."

Etihad Rail engineers have travelled to deserts in China and looked to Saudi Arabia and Mauritania for answers. Chinese railways have plants that can turn sand dunes to clay over 20 to 30 years. Saudi Arabia has sand-sucking locomotives that push sand particles away from the engine. Mauritania has "sand patrols" - motorists who monitor dune movement.

"The sand moves over a period of months and years so you have to keep an eye on this and deal with it before it comes to you," Mr Malak said.

Then there is the topography. Ditches or hills alongside the track can act as sand traps, while both wind and sand can be controlled by planting walls of vegetation.

These were just some of the ideas proposed by sand-mitigation experts from China Railway First Survey and Design Institute at a workshop last month. Any such measures would be carried out in coordination with the Environmental Agency - Abu Dhabi.

"We're very conscious of the environment and any aspects that change nature around the area," Mr Malak said.

Of course, nothing beats local know-how. To that end, Etihad Rail has paired up with Bedouin farmers and the Ruler's court in the Western Region to trace the path and pattern of local dunes.

"Without these people we could not have found the best route," Mr Malak said.

"We have some very knowledgeable people working there. They are Bedouin farmers but they're also engineers."

This intimate knowledge of the dunes was the basis for the route map of the first section. The first stage runs due south from Madinat Zayed before it curves behind the protection of Liwa Oasis to Shah. The second stage will connect Ruwais to the Saudi Arabian border at Ghweifat, and Tarif to Jebel Ali and Al Ain. The final stage will connect the northern and eastern emirates.

"That area is all just sand and you have to be very familiar with it," said Dr Hazem Mubarek, the executive director of infrastructure for Etihad Rail. "So you look at where the green line [of the oasis] is, it's very flat and the movement of the sand is very, very slow, so it's a natural sand mitigation chosen by the alignment itself.

"First and foremost, the sand mitigation method is the choice of the alignment," Dr Mubarek said. "You try as much as you can to align your tracks with the movement of the sand."

There will be a station to monitor the weather. If things get bad in sandstorm season, usually March to July, there are ploughs.

"Like snow ploughs," said Graeme Overall, the director of business development at Etihad Rail. "That desert environment - you think of it as empty but it's not," he said. "As soon as you try to do some work in the area you find it's full of life and activity."

The most sand-prone area is likely to be from Madinat Zayed south towards the edge of the Empty Quarter.

Though sand differs from emirate to emirate - from the rusty sands of Ras Al Khaimah to the creamy dunes of Abu Dhabi, it all comes down to particle size. Problems are caused by the large, heavy particles that "just stick around" near the base of the rails to obstruct tracks.

So from China to Mauritania, the sands will vary but, as Dr Mubarek said: "These fundamental solutions are pretty much the same."

azacharias@thenational.ae