Belly of the beast: FAST's Riyadh Metro TBMs

Belly of the beast: FAST's Riyadh Metro TBMs
Published: 7 March 2016 - 6:12 a.m.
By: John Bambridge

The political capital of the Kingdom of Saudi Arabia, Riyadh, has long fallen short of many of its international peers in terms of infrastructure — its traffic issues crippling the commute of its six million inhabitants for want of public transport.

However, all of that is set to change with the construction of the Riyadh Metro — to date the largest mass transit system to leave the drawing board in the Middle East and a project more befitting of the largest city in the GCC.

The project, which is being facilitated by the Arriyadh Development Authority (ADA), comprises a network of six rail lines with a total length of 176km and some 85 stations — larger in both degrees than the three-line section of the Doha Metro that is currently under construction, though more is planned.

Engineer Ahmed Aldrees, ADA assistant project director for Package 3, explains: “Perhaps 12 years ago the traffic plan for Riyadh showed that the problem of the traffic could not be solved only by building new roads or extending existing ones.

“Today, we are working on one of the biggest projects in the world, in a crowded city, surrounded by people, traffic and utilities.”

The six lines of the project involve a mosaic of track situated at grade, overhead on viaducts and underground, combining cut-and-cover excavation and, of course, the deployment of tunnel-boring machines (TBMs).

At tendering, these six lines were split across three packages. The third package comprises Lines 4, 5 and 6, and is worth $7.82bn. It was secured by the FAST Consortium — led by the Spanish construction group FCC, and including Samsung C&T, Alstom, Strukton, Freyssinet Saudi Arabia, Atkins, Typsa and Setec.

Aldrees explains: “At 63km, Package 3 is the biggest in terms of line length — so keeping everyone calm and explaining the importance of the project is one of the biggest challenges.”

Enter the project’s seven TBMs, which are being deployed on the sections of the line where there is either no space at grade or the layout of the city is unconducive to either viaducts or cut-and-cover excavation.

Six of the seven TBMs are manufactured by Germany’s Herrenknecht, the leader in the segment since 1975, while the final machine was supplied by France’s NFM Technologies.

Aldrees details: “Across the whole project — 51km of which is underground — 37km will be executed by TBM and the other 14km by regular cut-and-cover excavation.”

At 13km, the subterranean Line 5 accounts for approximately a third of the TBM work on the project, running along King Abdulaziz Street between transfer stations with Lines 1 and 2, interspersed with 11 additional stations.


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