Challenges rise,Metro digs deeperhttps://indianexpress.com/article/cities/delhi/challenges-rise-metro-digs-deeper/

Challenges rise,Metro digs deeper

Delhi Metro faces its toughest challenge yet as Phase-III expansion gets underway. Snaking through the city’s most congested areas,it attempts to balance cutting edge technology under the ground with minimal interference to life above

The 140-km-long Metro Phase-III will see the use of some of the most sophisticated systems for Metro expansion till date.

Apart from a Centralised Data Management System,that will be used to monitor data generated by 34 Tunnel Boring Machines (TBM),the Delhi Metro Rail Corporation (DMRC) will introduce Mass Spring System (MSS) to mitigate vibrations.

Centralised Data Management System

The Centralised Data Management System will provide immediate information on physical progress of tunnels,the correctness of its alignment,ground settlement and the status of buildings and structures along the

underground alignment.

The system will act as a tool for data acquisition,visualisation,reporting and,consequently,as a tool for risk minimisation.

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“Phase-III has an underground network spread over 52.7 km and will have 30 underground stations. Underground construction requires utmost precision,for which 34 mammoth TBMs will be used. Therefore,a centralised data management system has been put in place for constant surveillance,” a senior Delhi Metro official said.

The use of 34 TBMs for the Metro Phase-III would be among the highest number of TBMs used in any urban centre in any part of the world around the same time. In Phase-II,when 34.89 kilometres of underground corridors were built,the DMRC used 14 TBMs.

The tunnelling of Phase-III is

expected to be complete by mid-2015.

Mass Spring System

Mass Spring Systems (MSS) on the tracks is being introduced to improve efficiency in the construction of the underground section. The system,officials say,uses world-class technology to prevent any kind of vibration generated by Metro trains from reaching structures above the tunnels.

“The MSS helps mitigate vibrations generated by trains at the source itself. MSS elastically separates the track slabs in the tunnels or on viaducts from the supporting structure. Its use also helps in minimising transmission of vibrations (structure-borne noise) to establishments in the vicinity of the tracks,” the official said.

Communication Based Train Control

Majorly overhauling the signalling system,the DMRC has proposed introduction of Communication Based Train Control (CBTC) system to enable running trains at shorter frequencies. With this technology in place,the existing fleet of trains will be able to make more trips. The signalling technology will allow trains to run at a frequency of 100 to 120 seconds. At present,trains run at a frequency of about 2.5 minutes or 180 seconds.

Superstructure Upgrades

The design of Phase-III superstructure (viaduct) for upcoming Metro lines will be different from those in Phase I and II. The new superstructure layout is based on technological enhancement and the alignment of the elevated Phase-III lines.

“The piers are going to be plain and will not have a fluted pattern. These new piers will not allow dust and pollutants to stick to them.

Twelve special spans will be built

using cantilever construction (CLC) and 10 special steel spans will be constructed on the viaducts at crossings,water drains,railway lines,” a Metro official said.

Special spans will be used at railway crossings in Anand Vihar,Mayur Vihar Phase-I station,nallah crossing in Patparganj Industrial area,Shakurpur railway crossing,Punjabi Bagh Chowk,Rajouri Garden and Mayapuri (Ring Road).

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Sensitive cables,such as the signalling cables,will be protected from

ultra violet rays through covers mounted on them.