For over 170 years, the World Expos have showcased innovations that have left a lasting impact on their host cities, the local region, and even globally. These mega-events have not only raised a city’s profile and promoted economic growth, they have also created legacies of unique landmarks and societal influences, such as the world-famous Eiffel Tower.
The heart of the Expo 2020 Dubai event was the Al Wasl Plaza. Featuring a massive, 130m-diameter steel dome topped by a 67m-high trellis, it served as a central hub for the Expo. The Al Wasl Plaza Dome is also the world’s largest 360-degree projection surface, which was designed to create an immersive experience for the visitors within while also being visible to those outside. This fusion of engineering, history, technology, and media has already been labelled as a global masterpiece and will be this World Expo’s legacy.
RIMOND CIMOLAI was the principal contractor for the construction of the Al Wasl Plaza Dome. The scope of works included the installation of the steelwork; systems for shading, building maintenance unit (BMU), MEP, and LED lighting; and the enclosures for projectors and speakers. However, the project had tight timescales and stringent sustainability requirements, as well as the logistical challenge of working around 200 other live sites. To achieve this, RIMOND championed a collaborative culture – as well as a digital approach and off-site construction – to offer a fast-track solution that would ensure the timely and successful delivery of this politically sensitive and challenging venture.
The Al Wasl Plaza Dome was an incredibly complex structure to build. The complicated geometry and the interaction between it and the large number of building systems, media equipment, and technology was difficult to fully understand from 2D drawings alone. Not only was the design intent much harder to interpret, so was comprehending how the different systems affected each other. Delivering the project on time and in the tight timescales allowed despite the complexity of the build was one of the biggest hurdles.
Managing a Congested Development Site
There was also the task of building one of the world’s largest domes on a space-limited site within the larger Expo 2020 development. As there were five other large buildings being constructed in the same vicinity, as well as more than 200 other sites within the project extents, coordination between the various construction projects – as well as managing the deliveries, construction methods, working areas, materials storage, and other site issues – presented a huge logistical challenge. Added to this was the fact that the site was located over a tunnel structure, which meant there were many limitations on what construction methodologies could be used. Working at height was another concern, and so the construction methods proposed needed to avoid putting workers at unnecessary risk wherever possible.
Engineering a Bespoke Building Maintenance Unit
As the dome incorporated many projector surfaces, access to the surface for maintenance and cleaning would be required on a regular basis. The dome would require the world’s largest BMU to achieve this, with a bespoke design that ensured it could reach all areas of the dome. Because of the unique geometry of the dome, this could only be achieved by attaching moving equipment to the dome which would slide on four rails and follow the shape of the dome at all levels. However, how to engineer and fabricate the complicated BMU and access system required careful consideration.
Meeting Demanding Architectural Standards
The architect had exacting standards for the construction, so standard materials and approaches were not always suitable. For example, the connections between the steel dome structure had to be seamless without any visible joints, yet also without compromising the structural integrity of the dome. Furthermore, the projector and speaker enclosures were a unique design that had never been built before and required aviation-level fabrication techniques that required a specialist. In addition, they required fabrication off-site in Mexico and then transporting fully built for installation on site in Dubai, despite being extremely large once fabricated.
Achieving Strict Sustainability Requirements
An added challenge was that the project was aiming to apply for the CEEQUAL sustainability assessment. This meant that there would be stringent requirements for sustainability performance, as well as other factors such as management, pollution and waste, natural resources, transport, and land use, among others.
Embedding a Collaborative Culture
From the outset, it was clear that with the number of sites and stakeholders involved in the project, collaboration would be the key to successful delivery. RIMOND CIMOLAI put forward and championed a collaborative culture, including everyone in the decision-making so that the best options for everyone involved on the project could be taken forward. This was useful for coordinating works between projects, as well as managing logistics effectively, such as site deliveries, equipment, materials storage, groundworks, temporary works, and health and safety concerns.
Enabling End-to-end Digital Solutions
To address the complexity of the project, an end-to-end digital methodology was adopted from the early stages. This meant that every aspect was digitally engineered before it was built on site, down to the last nut and bolt. Using information-rich 3D modelling, the design could be better communicated, understood, and coordinated thanks to the enhanced visualization that a digital approach enabled. RIMOND CIMOLAI created a digital wireframe model to integrate and coordinate all design disciplines, from the geometry of the structure to the MEP systems. From this model, BIM models were created for all the different disciplines, which enabled enhanced coordination between the supply chain and stakeholders.
Undertaking Robust Risk Analyses
Another benefit of a digital approach was the creation of visualized method statements. Because the construction was so complex and space so tight, RIMOND CIMOLAI undertook extensive risk analysis by creating step-by-step method statements using 3D visualizations of each work activity. This ensured that the design intent was clearly communicated to the site supervisors and workforce and allowed robust planning to be undertaken to reduce the safety risks as far as practicable.
Implementing Modern Methods of Construction
To overcome the congestion and space limitations on site, as well as to accelerate the construction schedule, RIMOND CIMOLAI proposed the use of prefabrication, preassembly, and off-site manufacture wherever possible. Prior to manufacture, the steel sections were optimized at the factory so that the deliveries could be rationalized into as few trips as possible. Larger sections of steel were preassembled to the maximum size and weight permitted by the roads on site and in accordance with the limitations of the lifting equipment. The preassembled sections included MEP services integrated within, so that installation was much quicker and safer. This innovative use of modern methods of construction reduced the works at height and the amount of work required on site, increased productivity and safety, and fast-tracked the schedule.
Engineering Innovative Construction Methods
The site congestion and local conditions (such as the tunnel) also affected the construction methods used. To overcome this, modular temporary structures were built to assist with installing components at height. They could be dismantled to save space if needed, as well as re-used throughout the construction process to save waste. Another issue was the steel erection in such a confined space. Together with Maffeis Engineering and Robert Bird International, RIMOND CIMOLAI designed a steel erection methodology that enabled the 550-tonne crown of the dome to be built on the ground and then lifted into position, 45 meters above ground level. To achieve this, 18 strand jacks were installed on posts, which lifted the dome – and carried a total weight of 800 tonnes, including the temporary supporting equipment – into place while ensuring millimeter-precision. As the tolerance allowed was only three millimeters, this accuracy was crucial to the build. It was attached using 53 temporary connection brackets, and required engineers to monitor the process using GPS sensors throughout the night to ensure the perfect alignment.
Meeting Exacting Architectural Requirements
Achieving the architectural specifications required some innovative approaches. For the steel dome, RIMOND CIMOLAI undertook custom steel connection design utilizing advanced parametric form finding methods in order to provide circular steel pipes that were seamlessly welded to avoid visible joints along the curvature of the dome, while still providing the required structural integrity. Over 1160 individual curved steel sections were installed to create the dome, which required more than 13km of steel pipes.
For the 42 projector and 12 speaker enclosures, an advanced fabrication methodology was adopted. The design intent required aviation-level fabrication techniques of aluminium double curving, complex GFRC cladding, and automated moving components connected to the plaza’s overall BMS system.
In addition, the materials that made up the enclosures were designed to be integrated and assembled in a factory setting in Mexico. Due to the size of the enclosures once fabricated, the only aircraft that could accommodate them was the Antonov plane, which is the largest air carrier in the world. RIMOND CIMOLAI commissioned two flights from Mexico to Dubai using the Antonov plane to deliver the enclosures on time to the construction site for installation.
Supplying the World’s Largest Building Maintenance Unit
There was also the issue of ensuring that the BMU for the dome and its access system could be fabricated and installed as per the designer’s concept. RIMOND CIMOLAI undertook extensive engineering work so that the design could be fabricated and installed optimally on site. This meant ensuring that the design was feasible, could be fabricated in parts that could be easily transported to site without requiring too much storage, and planning the construction sequencing.
After 19 months of construction, the Al Wasl Plaza Dome became the crowning jewel of the Expo, as well as its stunning heart. The speed of progress on site was a testament to the success of the collaborative culture of the team, as well as the innovative, off-site construction and digital approaches adopted. The project set a blistering pace that is almost unheard of in the construction industry despite the many challenges faced, while providing the highest quality, consistency, and safety standards.
The project has been awarded a CEEQUAL Whole Team Excellent certificate with a score of 93.6% – which is the highest rated project in the Middle East to date. In addition, despite the large number of workers on site – 1000 laborers on a daily basis both on- and off-site in 24-hour shifts – RIMOND CIMOLAI were recognised for their excellent health and safety and worker welfare performance with awards for both aspects from the organizer, Expo 2020 Dubai.