Metro project on track as 44 trains arrive at Jebel Ali

Four, out of the 17 planned trains, have been delivered in Dubai for the Green Line, according to the RTA.

"Currently 44 trains have arrived at the Jebel Ali depot and the post-delivery inspections on 42 of them have been completed," said Adnan Al Hammadi, Director Rail Projects Construction at the RTA in an exclusive with Emirates Business. "The routine dynamic tests have been completed on 25 trains."

Meanwhile, RTA has commenced a study to update and develop the next two metro lines and the tram lines, in line with its aim of developing an integrated Rail Transit Master Plan.

In February, a consultant was brought on board to study and determine the future plans and prospects for the Purple and Blue Lines, which will be required to meet the expected passenger demand in Dubai up to the year 2030.

"The results of the study will be revealed in December. Depending on the economic situation, future extensions of the rail would be implemented as necessary," said Al Hammadi. "The study will also provide a capital cost estimate and implementation programme for the proposed new lines, define their appropriate alignment corridors, the required locations for stations and depots, the type of technology for each line and the overall rail network requirements. It will also identify the best integration locations with the existing rail and other modes of transport, including the transit systems of private developers. "

He added: "The RTA is also conducting studies, which will detail plans to connect various proposed monorails with the Metro through climate controlled walkways and travellators. The details will be revealed shortly."

Construction update

Work is ongoing on all the 47 stations, including the two stations at the airport terminals 1 and 3. The Red Line track and power rail installation have been completed.The first layer of cladding works is complete on all the stations on this route. The automatic fare collection gate room frame and raised floor has been completed. Besides, around 90 per cent of the viaduct work has been completed on the Red Line.

Meanwhile, around 55 per cent of work and around 92 per cent of the viaducts have been currently completed on the Green Line. The erection of the steel structures is ongoing while other civil works is in progress on all the stations.

The overground section of the rail has a total length of 47.4km (see stations below), stretching from Rashidiya to Jebel Ali for the Red Line. It covers 15 km from Al Qusais 2 to Creek on the Green Line. The platform screen doors have been installed in 10 stations, including the underground stations.

Powering the Metro

The Metro project has three main power stations (MPS). MPS 1 and MPS 3 feed the entire Metro Red and Green lines, the entire power rail and the stations. MPS 2, which is located at Union Square, acts as a standby station if there be electrical faults at either station.

The two main power stations, MPS 1 and 2, have been completed, energised and handed over by the contractor to RTA and Dewa. The last MPS is now undergoing equipment testing before its energisation.

Longest train run

According to the scheduled timelines, the longest train run was successfully conducted from Jebel Ali to Emirates station covering approximately 49km out of 53km on the Red Line at a speed of 50kph.

Around 25 per cent of the operational control system has been installated so far. The test track has been extended to Marina station and static tests have been started at Jebel Ali Industrial, Jumeirah Lake Towers and Marina stations.

Innovations

The underground stations were constructed using the "Top down" method, which entails the construction of concrete diaphragm walls, also known as retaining walls, as the first step of construction. This was followed by excavation just below the roof slab level of the underground structure, while the diaphragm walls and structural steel support the soil at the sides. The roof slab was then constructed, providing a support across the excavation. Access openings on the roof slab were provided to proceed downwards to the base slab level of the structure.

The next level of slab was constructed, and this process continued downwards until the base slab was completed. Upon completion of the base slab, the side-walls were constructed and the intermediate steel structures were progressively removed. The access openings on the roof slab were then sealed and the ground was subsequently back-filled and reinstated.

The tunnelling on both the Red and Green line was completed in December 2008 and the tunnel boring machines (TBM) have been dismantled, Al Hammadi said.

The TBM was introduced for the first time in Dubai in the tunnelling of the underground stations. They were used to excavate tunnels with a circular cross section and in various grounds: rock, sand and so on. The TBMs employed in this project were the Earth Pressure Balanced (EPB) types with confined pressurised excavation chambers. They were equipped with cutting heads, including special blades for cutting weak rock as well as a foam injector at the excavation face for improving the fluidity of the excavated spoil; thus decreasing the damage to the cutting heads.

The TBMs were used to excavate a total of 8.5km stretch of tunnels. Two TBMs were used for the Red Line and three on the Green line.

Launching girders

The launching girder method is commonly used in erecting segmental bridges and railways. Launching girders are used to lift and position the viaduct segments for the elevated section. A total of ten launching girders are being used on this project. They are strategically placed at various locations at the beginning of the launch but are moved upon completion of the planned number of spans.

The girders provide fast track installation process, which enables the installation of a complete viaduct span in about two days.

Concrete segments are pre-cast and transported by trucks to the various sites. Totally, 12,730 pre-cast concrete segments will be used on the Red Line, each segment weighing about 50 tonnes. The girders are positioned over a span to be constructed and supported by a tower connected to the end of the deck and the next pier.

The standard beams are used for positioning single or double track segments with lengths varying between 20 metres and 44 metres, while special girders are used for single track stations (Nakheel and Rashidiya).

Viaducts detail

The Dubai Metro project includes around 60km of viaducts; 45km for the Red Line and 15km for the Green Line. Viaducts are the series of precast post-tensioned concrete segments supported by piers and they carry the railway track. The U-shaped section of the viaduct maintains the vertical rail alignment as low as possible to effectively contain the noise radiating from track level in order to minimise impacting the surrounding environment.

The current status

"There are a few activities left to be done on the Metro," said Al Hammadi. "The entire project team is fully committed to complete the project on time for its 9/9/9 deadline. The main activities for the Red Line include the completion of the fitting out works and cladding installation to the stations and entrance pods, completion of the viaduct emergency evacuation staircases, completion of the access roads to the stations, fitting out and cladding installation to the car parks and depots, and testing and commissioning of the sophisticated railway systems. Most, if not all, of these activities have already started. The project workforce is making an enormous effort to complete these as quickly as possible."

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