Al Tayer chairs workshop on the tunneling process and the viaduct construction for the Dubai Metro project

Under the directive and attendance of HE Mattar Al Tayer, Chairman and Executive Director of Roads and Transport Authority (RTA), the contractors for the Red & Green Line of the Dubai Metro Project, Dubai Rapid Link (DURL) organized a workshop on the processes involved in the construction of the Dubai Metro tunnel including a presentation on "Al Wgaisha" the tunnel boring machine (TBM) and the tunneling process, and on the construction of the Red Line viaduct on which the Metro will travel over-ground; the workshop was held at Le Meridien hotel near the RTA main offices on the 14th of January 2007.

Among the attendees were Engineer AbdulMajid AlKhaja, CEO of the Rail Agency and numerous directors from the Rail Agency as well as other departments within RTA. The workshop's attendance exceeded expectations as over 60 professionals and officials from all parties involved in the Metro project - contractors, subcontractors and consultants - all came together to be educated and share their thoughts.

DURL's Assistant Project Director, Michael Black - who has 30 years experience in the rail systems field - gave an introductory speech in which he welcomed all attendees to the educative and interactive workshop. This was followed by the first presentation about the TBM and tunneling process which was given by Tunnel Design Manager, Paul Groves, who has over 17 years experience in several different similar projects worldwide including the metro systems in China and UK. After a break during which all parties interacted socially as well as professionally over a comfortable lunch gathering, the second presentation on the viaduct construction processes was presented by DURL's Project Manager for the Dubai Metro, Talib Ankail, who has 23 years' experience working on rail systems in Puerto Rico and Malaysia.

Engineer Groves presented a detailed introduction to the tunnel boring machine (TBM), or "Al Wugeisha", including a description of the machine's components - which were ordered specifically for the Dubai Metro project based on studies of the soil and earth that will be excavated in Dubai - alongside an explanation of the way these components are structured, their functions and how the machine is constructed. On the operation of the machine, it was stated that the TBM excavates sand and breaks down rocks in the earth as it creates the circular tunnel in an environment-friendly way.

The Dubai Metro Project Manager also enlightened the attendees with detailed information on the operation of the TBM. Part of the tunneling process is installing the tunnel lining; 6,300 reinforced concrete rings, each weighing 42 tons, will be used to maintain the space under the earth which the TBM creates by excavating, thereby generating an actual underground lined tunnel for the Metro step by step as "Al Wugeisha" moves along on its designated 1.5km route from Union Square to Burjuman.

The presentation highlighted the methods of prevention and mitigation of possible disturbance that the TBM could cause during the tunneling process, and explanatory charts showed that the most problem-prone areas on the tunnel's route are directly under the creek and in the Al Ras area. Engineer Groves also stated that the contractors have extensive experience in working with such soil and earth as found in Dubai.

The presentation was concluded with a session on safety and the precautionary steps taken to eliminate and/or deal with potential unforeseen risks in case of their arrival. Engineer Groves explained that an emergency team will be heavily trained to work on site around the clock on monitoring the TBM and its operation's effects on the earth and on the over-ground buildings and roads. RTA and DURL have implemented extensive safety-ensuring plans to ensure the entire tunneling process is completed according to comprehensive planning. Precautionary measures and emergency action plans are to be implemented in collaboration with Dubai Civil Defense, Dubai Police as well Dubai Government's Department of Health and Medical Services.

The second presentation given by Engineer Talib Ankail, DURL's Dubai Metro Project Manager, was composed of an educative and comprehensive display of the processes of fabricating the pre-cast segments of the Dubai Metro viaduct, their transportation to the site, their installation and the operation of the 7 launching girders used to construct the 47km Red Line viaduct.

Starting with an introduction on the 539 thousand square meters Casting Yard in Jebel Ali - one of two casting yards built and dedicated to the project - it was explained that the yard is where all concrete pier caps and viaduct span segments for the Red & Green Lines are made. The Red Line viaducts comprise a total of 11,400 span segments of 42-70 meters width, each weighing 49-90 tons, and 1225 piers and pier caps.

Engineer Ankail gave a detailed explanation of the operations and process occurring on the casting yard in order to produce the Red Line viaduct, as well as the operation of the different kinds of launching girders used to lift and place the segments onto the pier caps to construct the viaduct. The first girder to be used for construction will be at the Jumeira Islands Station site, and he described it to be 109 meters long and 13 meters wide, stressing that the girder has undergone all necessary tests, executed by an third-party safety and quality assessor, to ensure elimination of potential accidents during the process of construction.

The presentator also informed the attendees of the specifics of each different launching girder and how the viaduct will be constructed, based on the ground, station design and traffic conditions at each respective site. The construction plans for each site have been individually designed to minimize the effects on traffic, based on the extensive civil studies done at the sites and the contractors' experience with the equipment and in the field, all in collaboration with RTA's Roads & Traffic Department and Dubai Police.

Engineer Ankail concluded the educative presentation with a summary of the contractors' world-wide experience in constructing rail systems, encompassing the metro systems currently up and running in Malaysia, Singapore and Hong Kong.

Each presentation was concluded with a question and answer session, where the attendees were given the floor to discuss the presented issues and put forward enquiries which the DURL engineers proficiently addressed with clarifications and safety reassurances. It was consented upon that the seminar was highly educative and many attendees expressed their gratification for such interactive and professionally educative experiences.

Dubai Rapid Link (DURL), a consortium of four companies headed by Mitsubishi Heavy Industries of Japan, won the contract to build a high-tech driverless rail transit system across Dubai in May 2005. The Consortium's remaining members include Japanese Obayashi, Kajima and Mitsubishi corporations and the Turkish, Yapi Merkezi.