The electrically-powered tram system, which uses a groundbreaking form of battery-charging (modular on board energy storage unit) technology, is open to the public and carries passengers around Qatar Foundation’s ‘Academic Loop’ – where it’s numerous schools and two universities are located, as well as the Green Spine and the Education City Stadium. The implementation of a hybrid energy storage solution allows for a catenary free tram to avoid the visual impacts of an overhead contact system. The tram operates by charging via pantograph contact to an overhead charging rail located at each station and stop. For tram operation between stops, the power is provided by super capacitors, and in the case of degraded modes or long distances between charging stations, by a battery. Depending on the topography of the line, charging times are expected to be between five and 22 seconds, and a calculated dwell time of 20 seconds covers the required charging time.

The design challenges lie in the structural design, climate responsiveness and user comfort. The original design concept for the tram stops is based on an integration of structure and enclosure in such a way that the architecture and the structure become essentially one and the same. The minimal enclosure that results, in the form of the mast supported canopy hovering above the platform, demands a careful integration of the myriad building services required to support the tram stops. To achieve a high level of integration, the support structure for the overhead charging rail is utilized as an armature for service routing resulting in a sort of central nervous system of power and data hovering between the canopy and the platforms.

Regarding the canopy, this structural configuration involves a cable net suspended above 6 columns, and allows for clear views into, out of, and through the stop. The configuration offers opportunities for enhanced daylighting, transparency and visibility. Further, the design of the whole cable net structure was developed to be prefabricated which not only offers added quality assurance. Moreover, constructing pieces quickly offsite result in reduced pollution and disturbance of jobsite. The controlled shop environment saves on water usage and enables the recycling of scraps and other materials. Additionally, the repetition of custom elements supports the concept of a linewide identity while also enabling a more efficient fabrication and construction process. An economy of scale is achieved in the production of repeated elements, with further efficiencies realized in the erection of such structures, where the same erection process can be employed for multiple structures.

Underneath the canopies, a glass-enclosed waiting room is situated on each platform to provide a conditioned place for waiting during extreme weather. The waiting areas are the only spaces being conditioned in the project. Two indoor units are provided for each waiting area each sized for 50% capacity. If one unit was to fail the remaining unit would provide 50% of the peak load. The client envisioned a state-of-the-art LRT system that set new precedents in sustainable design. This has been realized in part through an architecturally integrated battery-powered system that relies on ‘recharging’ at each station or stop. The project’s innovative and ambitious charging stations and stops begin to realize the future of sustainable LRT travel.

Key

1. Canopy – The arrangement of the glass panels that comprise the canopy is designed to provide shading during the day, and to reflect light and project the night sky in the evening. Canopy integrated PV systems were extensively studied. Available solar energy falling on an unshaded canopy is between 1550 and 1850 kWh/ m2 annually. Further review concluded that PV would not be appropriate for two reasons: (a) providing areas for canopy maintenance access would reduce the area available for the PV arrays which reduces the energy output considerably, and (b) shading for some stations that are located close to tall neighboring buildings would also have a significant reduction in output power production.

2. Ventilation – The open-air design allows for cross ventilation of the platforms.

3. Waiting shelters – To reduce cooling loads in the waiting shelters, the glass facades have an IGU integrated fixed louver system to optimize incidental light and shading. These glass facades selectively transmit daylight and protect against solar heat gain in order to create a comfortable waiting environment. A single waiting enclosure will be approximately 28,000 kWh annually for the HVAC system and lights.

4. Structure – The structure supports components for the tram’s unique propulsion system, a hybrid energy storage solution that utilizes batteries that recharge via an overhead charging rail at each stop. This system eliminates the need for expensive and obtrusive overhead catenary wiring. The charging rail acts as a sort of central nervous system of power and data, hovering between the canopy and platform.

5. Power – Power for the charging rails comes from an underground substation nearby and is routed up the corner columns. The high voltage system is completely contained/hidden within the structure.