Works on track for seam­less MRT link at Or­chard sta­tion

New meth­ods used to con­nect NSL, TEL plat­forms hailed as ma­jor engi­neer­ing feat

The Straits Times - - OPINION - Zhaki Ab­dul­lah Trench­less un­der­pass con­struc­tion by pipe roof­ing

When the Thom­son-East Coast Line (TEL) sec­tion of Or­chard MRT sta­tion opens in 2021, com­muters can en­joy a seam­less trans­fer be­tween the North-South Line (NSL) and TEL plat­forms, thanks to a pas­sage­way run­ning be­neath Or­chard Boule­vard.

The Land Trans­port Au­thor­ity (LTA) re­vealed yes­ter­day how this is be­ing con­structed with­out dis­rupt­ing the heavy traf­fic along Or­chard Boule­vard or in­con­ve­nienc­ing com­muters us­ing Or­chard MRT sta­tion.

A method called pipe-roof­ing is be­ing used for the first time on an MRT project here. It in­volves cre­at­ing an un­der­ground canopy of in­ter­locked steel pipes, each with a di­am­e­ter of 1.2m, around the tun­nel.

This al­lows min­ing to be car­ried out with­out com­pro­mis­ing the road or build­ings above, ac­cord­ing to Mr Henry Foo, the LTA’s deputy group di­rec­tor for the TEL and the Cross Is­land Line.

Mi­cro tun­nel-bor­ing ma­chines were de­ployed to tun­nel through the ground to in­stall the pipes. These are about eight times smaller than the reg­u­lar ones used for MRT tun­nelling. The use of in­ter­lock­ing pipes also pre­vents mis­align­ment and break­age of the pipes.

Prior to the con­struc­tion of the canopy, work was done to sta­bilise the ground and pre­vent wa­ter from leak­ing into the tun­nel. Steel frame sup­ports were in­stalled later on.

Min­ing within this set-up was com­pleted last De­cem­ber and a per­ma­nent con­crete tun­nel is cur­rently be­ing built.

The min­ing and un­der­pin­ning be­ing done un­der­neath Or­chard MRT sta­tion to con­nect the two plat­forms are a “ma­jor engi­neer­ing feat”, said Mr Foo.

It is done us­ing spe­cial drilling ma­chines, which can drill in all di­rec­tions within a con­fined space. The work has to be done in­cre­men­tally so as not to dis­rupt train ser­vices.

Work will also be done to Or­chard MRT sta­tion to add es­ca­la­tors, a lift and a stair­case to link to the TEL plat­form.

The LTA said “de­tailed plan­ning and close co­or­di­na­tion” were be­ing done with trans­port op­er­a­tor SMRT so as not to dis­rupt sta­tion op­er­a­tions or inconvenience com­muters, adding that most of these works can be done only af­ter ser­vice hours.

A sep­a­rate pedes­trian un­der­pass is also be­ing con­structed to con­nect the TEL sec­tion of the in­ter­change sta­tion to Ion Or­chard and Whee­lock Place malls.

Se­nior Min­is­ter of State for Trans­port Janil Puthuc­heary, who vis­ited the work­site yes­ter­day, said these works showed the in­no­va­tion and smart engi­neer­ing be­ing em­ployed in the con­struc­tion of the TEL.

The ex­pan­sion of Sin­ga­pore’s rail net­work is not with­out its prob­lems, he added.

“As our net­work be­comes denser and longer, the con­sid­er­a­tion of what we have to do next changes, be­cause we don’t want to in­ter­fere with what we have to­day (the ex­ist­ing MRT lines),” he said.

When com­pleted, the 43km­long TEL will have 31 sta­tions stretch­ing from Wood­lands North to Sungei Be­dok.

It will open in stages from next year, be­gin­ning with three sta­tions – Wood­lands North, Wood­lands and Wood­lands South.

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