Regional rail projects have always had to contend with technological challenges. When the Hejaz Railway started operating in September 1908 after eight years of construction by the Ottomans, freight and passenger traffic quickly soared. In 1913, its fifth year of operation, the railway transported nearly 233,000 passengers and 112,000 tonnes of freight.
The popularity of the Hejaz rail link was not a surprise. The railways 1,320-kilometre-long main line from Damascus to the holy city of Medina via Amman cut travelling time across the popular pilgrim and trade route from about two months by camel caravan to only 55 hours by train.
Unfortunately, the success did not last long. During the First World War, sections of the railway were damaged and the line subsequently closed. Parts of it later reopened in Jordan and Syria, but political differences in the wider region prevented cross-border operations from restarting.
Weather and geography presented as much of a challenge as politics to the railways builders. The terrain that the line cut through ranged from very soft and sandy ground to solid rock formations, making construction a difficult undertaking. In addition, the regions harsh climate characterised by extreme heat, dust, sandstorms and the occasional flash flood put severe strain not only on construction workers, but also on the infrastructure itself.
Control of nuisance sand and sand dunes are a special challenge that warrants careful consideration
Geoff Leffek, Hyder Consulting Middle East
The regions specific climatic, geological and geographical conditions, combined with cheap fuel prices and concerns over high initial investment costs, have been major obstacles to the revival of railroads on the Arabian peninsula ever since. Apart from a small section in Saudi Arabia, railways have been virtually non-existent in the GCC.
Challenges of maintaining the railway network in such unfavourable conditions have dissuaded both governments and rail infrastructure builders from undertaking railway projects in these countries, said US research firm Frost & Sullivan in a 2011 report on GCC rail.
Today, 100 years after the Hejaz Railways most successful year of operations, the Gulf region is embracing rail projects once again. Flush with petrodollars from a decade of high oil prices, and driven by the need to modernise their transportation infrastructure and diversify local economies, the GCC states are gearing up to spend in excess of $100bn on rail projects until 2030, according to industry estimates.
But while the political and economic frameworks in the Gulf region have become much more favourable to implementing cross-border projects at a time when GCC states are pursuing a path of greater economic integration, the regions inhospitable environment and climate remain obstacles that must be overcome in the installation and operation of railway systems.
Geoff Leffek, regional rail director at Hyder Consulting Middle East, says ground conditions and sand mitigation constitute the biggest technical challenges for railway projects in the Gulf region.
The former ranges from hard rock to soft sabkha [salt flats]. High water tables and aggressive ground water require special design solutions with respect to buoyancy of underground structures and durability of concrete, says Leffek. Control of nuisance sand and sand dunes are a special challenge, while not unique to this region, which still warrants careful consideration.
Nuisance sand, which is essentially the accumulation of sand and dust on tracks that affects the way wheels run over the rails, leads to excessive wheel wear and affects braking performance. Mobile sand dunes next to the track not only contribute to the build-up of nuisance sand, but can also pose a substantial risk in their own right as there is danger of them engulfing both track formation and rails.
In general, for rail projects in the Middle East or elsewhere, some basic studies will always have to be completed, says Samer Tamimi, Abu Dhabi-based vice-president at US consultancy Hill International.
The first is an underground and sub-surface study that will look at the type of soil, suitable material and so on. This is important for determining the rail alignment. Another study is on sand and dunes to see in which direction they will move with the wind.
In addition, in the Middle East, due to the sand, a study will also be needed for soil stabilisation that will facilitate the application of the consolidation technology before laying the railway tracks, he adds. Also, there will be a need to monitor the wind to see where it may deposit the sand granules. This may call for the construction of sand barriers.
Once the direction of sand movements has been determined, alignment of the rail track will be altered accordingly.
Etihad Rail, the UAEs national railway company, is in the process of building a federal rail link. The $1.3bn Shah-Habshan-Ruwais freight line will transport granulated sulphur from the Shah sour gas field on the northern edge of the Rub al-Khali (Empty Quarter) desert to the Gulf port of Ruwais for export. The 264km railway will run through Abu Dhabis Western Region.
Etihad Rail has completed a geomorphologic study and computer modelling of sand dunes to determine the risks posed by the terrain. Sand ingress is one of the main problems. Sand getting into the rail tracks ballast is not immediately apparent, but is a serious concern in terms of reduced rail and sleeper life.
The track systems resilience is gradually destroyed by the sands ingress into the ballast, with the track bed ultimately becoming a tightly packed, almost solid mass, the company says in a report. As the resilience reduces, the effects will become apparent in terms of increased rail wear (rail head corrugations and shelling) and eventually sleeper cracking. These defects can ultimately cause a derailment if remedial maintenance work is not instigated, and their effect can be further heightened by the increased dynamic loading caused by heavy axle loads and high-speed traffic.
Mitigation measures against the various threats resulting from moving sands include barriers in the form of vegetation belts, sand fences, or sand and wind dykes, or a combination of barriers. Crosswind and sandstorm detection systems and ground penetrating radars that detect anomalies in the ground also tend to be employed. Once the railway is operational, on-track plant machinery equipped with sand vacuums is used to control sand contamination of the tracks.
The tracks themselves may also be designed to limit the effects of moving sand. Elevated rails sitting on special sleepers help prevent sand accumulation by allowing constant air drafts below the rails, according to one industry source working for a major European railway company.
Installing ballastless tracks instead of conventional ones is another option in desert situations, as wind-blown sands are unable to contaminate the track structure by entering the ballast and wheel-rail interface. A ballastless track system will be constructed for the Doha tram project in Qatar and, in Saudi Arabia, a 1km test section has been installed on the Riyadh-Hofuf rail link.
But sand is not the only challenge that rail builders in the Middle East are facing. Summer temperatures in the region can easily climb above 50 degrees Celsius. The extreme heat and intense sun pose potential risks to railway tracks as the steel they are made from can expand, leading to buckling of the tracks. The use of heat-treated steel grades that have higher wear and fatigue resistance mitigates stresses on the tracks, including those arising from high-speed trains and higher frequencies or axle loads.
Rolling stock and signalling and communication systems also need to be designed with the local terrain and environmental conditions in mind. At the same time, the highly-corrosive and aggressive climate in the Gulfs coastal areas makes the installation of fully dust- and watertight equipment a must.
Components manufactured for other parts of the world are typically designed to operate at a wide range of temperatures and are maintained in weather-tight enclosures that provided they have high ingress protection ratings will also be effective at protecting against the ingress of dust and sand. But air conditioning units will have to be more powerful than those used in cooler markets.
Dust and heat can adversely affect line-side signalling and communications equipment, says Leffek. On projects where it is necessary to bring power for line-side equipment to remote locations, research has been carried out to determine the viability of stand-alone solar power generators. Issues include the reliability of these devices, particularly where maintenance is sporadic, operability under adverse conditions, such as when the solar panel is obscured with dust, and system safety whether it is acceptable to rely solely upon solar power.
While the regions railway systems will, to a large extent, use technologies that have been tried and tested in other regions of the world, the fact that rail projects in the Gulf are almost all implemented on a greenfield basis means there is an opportunity to opt for the most appropriate systems from the outset and incorporate new solutions that take advantage of the local climate.
To this end, the plan is to develop a fully electrified rail system across the GCC in the not too distant future and utilise solar farms to generate the power required, says Leffek, although long-distance trains will initially use diesel-electric propulsion.
There may still be a long way to go, but even with the challenges the regions railway builders and operators are confronted with, there is little doubt that the long-term benefits of pushing ahead with these projects will have a lasting positive impact on the economy. And the technology to allow them to succeed is developing fast.
Doha Tram Solution
Qatar is developing a tram system that, instead of running on overhead contact lines, will use an energy storage system in which trains are supplied with electricity at the tram stops.
The project is being implemented by Germanys Siemens under a turnkey contract signed last year with the Qatar Foundation to supply a tram system for Doha. As part of the deal, Siemens will provide 19 Avenio trams equipped with the companys Sitras Hybrid Energy Storage system. The technology allows for the trams to be charged at each of the routes 25 stops, even during the shortest of halts, via centralised rectifier substations and distributed charging stations. In addition, up to 30 per cent of the energy supplied can be reused by recovering braking energy.
The 239-passenger cars will also be adapted to cope with the extreme climatic conditions. Along with an extra-powerful air-conditioning system, special sun shades on the roof will protect the electrical equipment from radiant heat. The low-floor design and arrangement of the double-leaf doors will allow passengers to get on and off quickly, shortening dwell time at stations.