King Abdullah Financial District (KAFD) station is one of the four main stations of Riyadh Metro, an infrastructure megaproject set to transform the way people travel in Saudi Arabia’s capital city. Thought to be the biggest elevated metro transfer station in the world at 32m high, 42m wide, and 232m long, it is raising the bar for architectural design and engineering.
Located west of King Fahd Road adjacent to the under-construction KAFD, the station will serve as the main interchange for Riyadh Metro, connecting Lines 1, 4, and 6, with skybridge access to a separate monorail system.
When you see this metro station finished, you’re going to see this long, continuous, white, nonstandard design. In my opinion this is one of the most beautiful station in Riyadh Metro because of that curved concept, there’s not a straight line on it and it’s going to be a fantastic backdrop.
The client is Riyadh Development Authority, which recently changed its name from the High Commission for the Development of Arriyadh, and Riyadh Metro is one of its biggest projects, with 85 metro stations and 176km of tracks.
More than 600 million man hours have been recorded with more than 60,000 workers mobilised across Riyadh Metro since construction started.
Parsons is part of the Riyadh Metro Transit Consultants consortium in charge of Lines 1, 2, and 3.
The BACS consortium of Bechtel, Almabani General Contractors, Consolidated Contractors Company, and Siemens is building Lines 1 and 2. Line 3 is being built by the ArRiyadh New Mobility Consortium (ANM), led by Italy’s Salini Impregilo, with India’s Larsen & Toubro, Nesma of Saudi Arabia, Ansaldo STS, Bombardier, Idom, and Worley Parsons.
Parsons is overseeing construction of these lines under RMTC as part of a three-way venture between French engineering companies Egis and Systra. Its scope includes project management oversight, construction supervision, and safety.
One of the interesting things about this project is that the structure is freestanding over the station and ties in at ground level.
There are so many impressive facts and figures for the station that it is difficult to know where to start. Do you start with the fact that 147,800m³ has already been excavated? That more than 10,000 tonnes (t) of rebar has been used? What about the 132km of wiring, 15.7km of piping, or 30.3km of cabling that the team has already set up?
Perhaps it’s best to start with what Ken Murray, senior vice president of US consultancy Parsons says. He believes the KAFD station will become a “fantastic backdrop” to one of the Gulf’s most important cities.
Designed by Zaha Hadid Architects, KAFD station features a complex geometric façade designed to resemble sine-waves.
Against the backdrop of chrome and steel skyscrapers, the metallic curvature forming the glass-reinforced concrete façade helps the station standout as an architectural landmark of the future. Murray admits that the engineering behind the façade is equally impressive.
“One of the interesting things about this project is that the structure is freestanding over the station and ties in at ground level,” he says. “What the team did from an engineering point of view is transfer the loads directly to the foundations, so the steel structure is supported by the foundations.”
As an engineering feat this is “pretty neat” because it creates a beautiful aesthetic without requiring any of the supporting structure to be seen, Murray says.
As the external steel structure weighs approximately 4,237 tonnes (t) with a further 2,785t for the interior steel structure, transferring the weight loads directly to the foundations is an impressive feat of engineering.
The pieces for the façade are made from curved steel initially welded in the UAE before being exported to Saudi and welded on site. During installation, the team faced two challenges, explains Murray.
“As they build the façade the structure starts to sag – and it sags a lot.”
During this stage the structure would sag by as much as 30cm and each side of the façade had to be built up at exactly the same time to prevent any temporary imbalances.
The structure would sag by a further 30cm when the cladding was put on, creating another challenge for the team. Both of these deflections had to be built into the early design and construction planning work.
And while it was a complex process to build a heavy freestanding steel façade, Murray believes it was the right decision because the station will “look fantastic” upon completion.
“When you see this metro station finished, you’re going to see this long, continuous, white, nonstandard design. In my opinion this is one of the most beautiful station in Riyadh Metro because of that curved concept, there’s not a straight line on it and it’s going to be a fantastic backdrop,” he adds.
KAFD station is similarly impressive on the inside. It is the only station in the network that will have underfloor cooling. The idea here is to prevent hot air from rising out of the ground.
To do this, workers have installed a network of small tubes carrying chilled water underneath the floor to mitigate the effects of heart absorption. These cooling systems are fed by cooling generators that will be used to cool the entire KAFD area.
In terms of efficiency and sustainability, KAFD station is targeting Leed Silver certification. Riyadh Development Authority has the option to upgrade this to Leed Gold certification in the future, which could see renewable energy capabilities added to the station.
Plans are already in place to recycle and retreat wastewater and the KAFD station may add solar power systems in the future, something that will support Saudi Arabia’s vision to a scale-up renewable energy.
The station also has a smart city-style ENVAC system to transport waste across KAFD to a site where garbage is compressed, treated, and segregated.
Waste from the station will be sucked up by huge tubes that will carry the trash underneath the financial district. Once the waste is treated and segregated, some of it can be transformed into an energy source.
Waste management has been carefully considered in the design of the station, which has also had to be carefully managed to ensure people can easily move around the 42,000m² floor area.
With seven elevators and 26 escalators, as well as two skybridges, people flow is something that seems to have been adequately taken care of.
The station will also have a number of shops, two levels of parking, potential future baggage handling systems, and two prayer rooms to provide passengers with a range of services at the Riyadh Metro’s main station.
Details are a big deal for the station too. Affixed to the ceiling above the ground floor are white and gold decorative moulds, each weighing up to 500kg on average.
These teardrop-shaped moulds are designed to resemble the pattern made in the sand dunes when wind blows over them. Each prefabricated mould is roughly five by two metres in size, and the team on site had to use special lifting equipment to fix them to the ceiling.
As part of the country’s commitment to Saudisation and the upskilling of locals, a large Saudi contingency makes up the project’s overall construction team. Parsons, says this varies through the different stages of project sequencing.
There is much to look forward to regarding KAFD station, as Riyadh will soon have a new architectural landmark that is thought to be the biggest elevated metro transfer station in the world.