The Qatar Foundation and Siemens signed a contract in 2012 for the turnkey construction of a 11.5km, catenary-free tramway system for the capital of Qatar. The order, worth upwards of €100 million, encompasses signalling and communication systems, electrification, depot equipment, some platform screen doors, and a fleet of 19 x 3-car Avenio trams.
The vehicles, each capable of carrying up to 239 passengers, will serve Doha’s Education City (see below), with the aim of creating a car-free campus and providing links to key locations through 24 stops along the route.
To ensure the tram is sufficiently robust to withstand the extremes of a hot desert country, the 27 x 2.55-metre platform is currently undergoing extreme trials at the Rail Tec Arsenal (RTA) in Austria.
No stone unturned
The RTA’s Climatic Wind Tunnel is fully equipped for testing the platform under typical weather conditions for both winter and summer operation. The data gathered will reveal whether the climate controls of the vehicle are capable of operating perfectly in temperatures ranging from zero to over 40 degrees Celsius. Measurements will also demonstrate, for example, if a fully occupied tram, operating in +40°C ambient temperatures at 30% humidity can maintain a programmed interior temperature of 25°C and continually provide passengers with sufficient fresh air.
“Inside the tram, humidifiers and heating pads are used to simulate the future passengers,” explains Gerald Buxbaum, product manager Avenio Doha, Siemens. “Sunlight is artificially produced with a solar field that can be varied in intensity up to 1,000 Watts per square metre,” he adds.
A heavy-duty air conditioning system and special shading on the tram roof are designed to protect against the desert country’s intense sun and high temperatures.
- The Qatar Foundation for Education, Science and Community Development is a private, non-profit organisation that serves the people of Qatar by supporting and operating programmess in three core mission areas: education, science and research, and community development
- Education City, an initiative of the Qatar Foundation, is located on the outskirts of Doha. The 14 square kilometre site houses educational facilities from school age to research level, together with branch campuses of some of the world’s universities
- The new tramway forms part of the Qatar National Vision 2030, published in July 2008. This plan outlines how the country will use the vast revenues from its substantial hydrocarbon resources to transform itself into a modern, knowledge-based economy
Charging through the extremes
As well as coping with the extreme clime, this Avenio will run in Doha without overhead contact lines (OCL). Further to saving on electrification costs, this kind of operation is particularly suitable for restrictive structural conditions, e.g. under bridges, at system switchovers or large intersections with several traffic systems, or for tram lines crossing areas of particular architectural interest where the presence of OCL would be an eyesore.
To deliver the power by another means, the trams will be fitted with Siemens‘ Sitras HES hybrid energy storage system, which is designed for rapid charging, even during the briefest of station stops (at the Climatic Wind Tunnel, the various charging cycles of this technology are also being put through their paces, at all temperatures). “This is the first of our trams to be fitted with this Sitras HES,” points out Mr Buxbaum. “Its first official test run, with the customer present, took place at our Wegberg-Wildenrath test and validation centre [50km west of Dusseldorf] in mid-April 2015.”
Recovery & reduction
The Sitra HES hybrid concept combines the benefits of a double layer capacitor (DLC), acting as the primary source of energy, with the properties of a Lithium-Ion traction battery system in the background, serving to extend the operating reach. Both components are mounted on the roof of the vehicle, and electrically linked to its feeder point via a DC chopper (DC/DC transformer). Under optimum operating conditions, through the recovery of braking energy, it should be possible to reduce the energy demand of a tram equipped with Sitras HES by up to 30% per year. One vehicle with a lower energy demand produces up to 80 metric tonnes less of CO2 emissions per year.
The system designed for Doha will function as follows:
- Acceleration – here the energy is taken from the DLC
- Batteries provide the energy for the extended distances
- During braking, the capacitors are recharged thanks to energy regeneration
- During dwell times, depending on the length of time available, both energy sources (batteries and capacitors) are recharged
“The charging process itself obviously needs to be guaranteed rapid and safe,” says Mr Buxbaum. “In a power context, ‘rapid’ means high charging power, which requires a lot of equipment. Also arcing must be avoided between the power arm in contact with the power rail on the tram. This is made possible by the tram receiving a signal when entering a charging station/stop, then adjusting its voltage accordingly to be the same or as close as possible to that of the station/stop.”
Unlocking opportunities with turnkey
A further defining feature of this Doha contract is its turnkey nature, which, in a nutshell, means one contractor is coordinating the various work packages, and will hand over the complete solution at the end.
“A turnkey approach streamlines the project organisation and running, with everyone ‘in the same boat’ – or in this case ‘tram’!” explains Mr Buxbaum. “The resulting fewer number of actors is certainly a good thing – it renders the whole task less complicated. But turnkey only works if the customer knows what they want,” he warns.
A further benefit worth also bearing in mind concerns financing – Siemens says potential backers find the prospect of dealing with a single contractor, rather than a multitude, more appealing.
Lesley Brown