Business & Money | Wednesday 22 April, 2015 12:05 am |

Qatar Railways Company (Qatar Rail), the company overseeing the construction of the Qatar’s integrated railway network, announced the completion of nearly 20km of tunnels dug on the Doha Metro project, a landmark that clearly highlights the progress of the tunneling works underneath Doha city.

The update was shared by Qatar Rail during a press conference held at the Millennium Hotel, which provided the most recent milestones shaping the path of the company’s near future undertakings; ones that will remodel Qatar’s urban landscape, infrastructure, and global role in the field of transport, shipping and logistics technologies.

Qatar Rail already received the 21 Tunnel Boring Machines (TBMs) assigned for the project, after being imported from Herrenknecht, the German world market leader in mechanized tunnelling technology. Most of Qatar Rail TBMs are currently operational, with expectations to successfully accomplish the tunneling phase by the second quarter of 2017.

Speaking at the occasion, Eng. Abdulla Abdulaziz T. Al Subaie, Managing Director of Qatar Rail, said:

"Qatar Rail has overcome many challenges to launch a successful tunneling phase at Doha Metro project. Our philosophy is to talk about what we have achieved, rather than share intangible promises. Today, we are pleased to announce the completion of nearly 20km of tunnels out of 113km; a development that we at Qatar Rail are proud of. Thanks to all workers and stakeholders contributing to the success of this national project in alignment with Qatar’s National vision 2030, the Doha Metro tunneling works are progressing as planned in adherence to global standards".

He added: "Keeping our residents and citizens convenience in mind, Qatar Rail was keen to implement most of the metro project underground where TBMs interfere very little with our vibrant city life through advanced technology and eco-friendly mechanism”.

The TBMs are a key component in implementing the Doha Metro innovative project; a high-tech mechanised alternative to conventional methods of design-and-build mining, drilling and blasting tunnels through everything from soft ground to hard rocks. They form circular tunnels through the rock, and can install concrete linings along the drilled sections to reinforce the bored tunnel and stabilise the ground.

The Doha Metro’s Red Line has launched all tunnel-boring machines, which are Lebretha, Al Mayeda, Al Khor, Al Biddaa, Lehwaila, Al Wakra, Msheireb, Doha and Al Zubara. Tunnelling works are progressing according to plan where the accumulative dug of these TBMs reached 11880m for both northern and southern sections. In parallel, the Green Line also launched its six TBMs with an accumulative tunneling of 6653m executed by Al Rayyan TBM, Al Gharrafa, Al Messila, Al Sheehaniya, Leatooriya and Lijmailiya TBMs, while the tunneling drive recorded 150m until now at the Gold Line, which has received its six tunnel-boring machines; Lusail, Sharq, Al Sadd, Al Waab, Al Sailiya and Ras bu Abboud (Airport City North).

Eng. Saad Ahmed Al Muhannadi, Chief Executive Officer of Qatar Rail, discussed the latest updates of the rail projects. He said:

“During the past year, we have achieved remarkable milestones on the Doha Metro and Lusail Light Rail Transit (LRT) projects thanks to the joint efforts of the company and its contractors. Particularly, the tunneling phase for the Doha Metro was successfully launched as we achieved great records of 11880m of tunnel dug at the Red Line, 6653m at the Green Line and 150m at the Gold Line. With skilled team and advanced machines, we were able to tackle obstacles and ensure works are moving forward”.

Commenting on complications that may occur during the TBMs operations underground, Al Muhannadi said: “Challenges are the rule of any innovative project similar to Qatar Rail’s current endeavor, and these encounters might be logistic - like finding the best way to manage excavations left-over at any site or between 2 different locations – or geo-technical, as no matter how good our surveys were, we will keep on discovering what the underground world is hiding from groundwater conditions, to voids and cavities”. He noted: “Technical hitches cannot be avoided while implementing such a huge and complex project, however, they can be dealt with in an efficient, effective and timely manner. We were proud of the team who handled a flooding situation at Al Bidda station earlier this year, which had no delay or impact on the Doha Metro progress. When and if such incidents occur, it is our duty to react immediately”.

A presentation on the Qatar Rail projects and the tunneling mechanism was also shared by Eng. Hamad Ibrahim Al Bishri, Deputy Chief Executive Officer of Qatar Rail. The demonstration gave insight on “the other life being led underground” showing the route of each TBM operating, the machinery details and the improvement at this stage.

Besides, Qatar Rail’s interactive event was followed by a site visit to Al Sudan Gold Line Underground station where attendees were able to inspect some of the tangible and concrete progress of Qatar Rail’s developments in general and the Tunnel Boring Machines (TBM) operations in specific.

Needing only one point of entry, TBMs can drill right below the city streets, practically unknown to the crowds above. They are also ideal for long lengths of uninterrupted tunnelling, as required by the Doha Metro project. Having limited environmental footprint, the machines have very little impact on the infamously high water levels that lie beneath Doha. Dust pollution associated with construction sites is virtually non-existent as all work takes place approximately 20 meters below the surface. The Doha Metro project is using 7 metre diameter TBMs, producing a tunnel with a diameter of 6.7 metres.

Before any tunneling begins ‘Pre Condition Surveys’ were carried out by Qatar Rail on buildings along the route. Key Monitoring Points were installed and actions taken to ensure that all works are carried out under the safest conditions. Among three major types of TBMs - Earth Pressure Balance (EPB), Slurry Shield and Open Face - the EPB machines were selected for Doha Metro due to the nature of the country’s geological makeup. This type of TBM is ideal for use in cohesive soft ground and rock conditions. Their name is derived from the fact that the pressure exerted by the machine itself is in equilibrium to the weight of the earth above it. While the machine drills through the ground, grout is injected straight into the ground to fill the overcutting gaps and stabilizing the ground.