Case study: Riyadh Metro’s Green Line

Construction of the $23bn Riyadh Metro is inching successfully towards completion with the recently finished Line 5. Hadi Khatib and Paromita Dey take a look at the schedule and the difficulties faced during Green Line’s timeline.

FAST deployed two 2,000 tonnes Herrenknecht TBMs for Line 5.
FAST deployed two 2,000 tonnes Herrenknecht TBMs for Line 5.

In June this year, the much-anticipated Riyadh Metro saw the completion of the excavation works for Line 5, also known as the Green Line. The $2.2bn (SAR8.26bn) Green Line is a part of the $23bn (SAR86.3bn) Riyadh metro network, which, once complete, will boast a total of six lines.

In mid-2013, three multibillion-dollar construction contracts were awarded to consortia headed by US-based Bechtel Corp, Spain’s Fomento de Construcciones Contratas, and Italy’s Ansaldo STS, respectively. Work on the project, facilitated by the Arriyadh Development Authority (ADA), began in 2014, and is expected to complete by the end of 2018.

The entire project encompasses 85 stations and six main lines covering 176km that will service most areas of Riyadh, including government, commercial and residential buildings, healthcare centres, schools, and more.

The metro will link King Khaled International Airport and the King Abdullah Financial Centre (KAFC), as well as connect with universities and other mass-transport systems in the cities.

In an interview with Construction Week, Eng Alwalid Alekrish, director of construction development projects and project director of the Riyadh Metro, ADA, says: “The authority, the contractor and the consortium were able to work as one team to complete the work on the Green Line, and that’s a source of pride to us.

“There were always concerns about tunnelling, given the complex and often unclear picture of the underground works. But we were able to overcome all obstacles and, as we inch nearer to the finish line, the excitement builds.”

The recently completed Line 5 runs underground along the length of King Abdulaziz Road (a main artery through the city of Riyadh) with 13km of bored tunnel, 11 underground stations, and transfer stations for the Red and Blue Lines.

The FAST consortium, led by Spanish construction group FCC, deployed two 2,000-tonne Herrenknecht Tunnel Boring Machines (TBMs), each 105m long and 19m in diameter, to excavate the bedrock beneath Riyadh for the fully subterranean line. Each TBM was carefully designed and selected by the FAST TBM team to match Saudi’s geographical conditions.

Jaime Freyre, project director for the FAST consortium, says: “Our strategic vision and goal is to reach the highest performance in the shortest time. This will benefit both FAST as the contractor and ADA as the client. The TBM and its auxiliary equipment was designed in a specific way to deliver excellent performance in the shortest time.”

But a project of such magnitude did come with its fair share of challenges. For example, traffic detouring in one of the busiest roads in Riyadh. Freyre says: “It was not easy but with the help of ADA, we managed it.”

Underground water also posed a hindrance for the excavation works. Freyre points out: “One of our main challenges was the southern part of Line 5, where the TBM encountered an inflow of underground water of 300m3 per hour, which occurred during the highest limit of the machine’s excavation capacity.

“In the south exit shaft, we even encountered an inflow of 1,000m3 per hour. These challenges were solved with our expertise and the machine’s unique design that allowed us to continue our work normally and maintain good performance.”

On another note, ADA was also highly instrumental when it came to facing risks of delays and costs, especially with regards to diverting both utility infrastructure and traffic. Alekrish says: “Even before the start of the civil works, ADA looked at those issues and created an executive committee that could handle them smoothly.”

The committee was represented by several agencies in the city, including the ministry of transport, Riyadh Municipality, the telecom ministry, water and power, and others. They were all stationed in ADA offices on the project site. “The committee was able to divert 200km of telecom, water and power lines, with little loss in cost, time and service to residents,” he adds.

ADA supervised work in over 200 metro locations and aimed to synchronise the work of diverting utilities and traffic with the help of – and in consultation with – residents. Alekrish says: “Working in close collaboration with Riyadh’s traffic division, members of the committee visited homes, and businesses in close vicinity to the project, received their input and were given a dedicated phone line through which they could communicate freely with committee members. This was a major step and has earned us credibility and trust with the residents of the community.”

With tunnelling in Line 5 complete, the next phase includes building the underground stations, and maintenance centres, while getting ready to lay the tracks. When these are complete, metro communication and control systems will follow, along with trains, testing, and integrating the rolling stock with control systems.

According to Freyre, the FAST consortium is now progressing with the construction of 11 deep underground stations and train depots, all linked by the tunnel, each of which will require the coordinated planning and management of several disciplines, including architectural, mechanical, electrical, and plumbing (MEP), track and transit systems.

“Coordination will also continue with external stakeholders, including Package 1 by the Bechtel-led consortium (BACS), which is constructing an underground interface station; the local electricity supplier for grid feeder connections; and client contractors for the installation of automatic fare-collection and station retail systems.”

Along with the progress in site works, the rolling stock continues to be manufactured and the ability to receive these trains at a functional depot remains a key target for the FAST consortium in order to facilitate the earliest achievable train testing.

ADA’s Alekrish says: “We have many of the system control units here in Riyadh, but testing is already underway abroad and this includes examination of individual components and equipment. Then testing of the train will be conducted here at our maintenance centre, as a first trial, and I expect these to begin within a year’s time.”

Despite a slump in Saudi’s oil revenues and the kingdom reviewing budget cuts, Alekrish is confident that this is not going to affect the metro project and its completion schedule. “Perhaps the conditions are not yet ripe for other similar projects, but Riyadh Metro benefitted from having been started prior to the slump in oil prices. So, not only the city but the entire kingdom will reap its rewards when the metro is completed. The surprise will be when a large number of people from all social classes want to use the metro,” he concludes.

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