C

arrying out a megaconstruction project like a mass rapid transit (MRT) system in the middle of congested Jakarta is a herculean task, and the hardest part is just about to start.

After two years of construction, the MRT project contractors will begin tunnelling underneath the capital'€™s thoroughfares from the Hotel Indonesia traffic circle in Central Jakarta to the Senayan traffic circle in South Jakarta in August.

The six underground stations that will be built on the stretch are Senayan, Istora, Bendungan Hilir, Setiabudi, Dukuh Atas and Hotel Indonesia (HI) traffic circle.

Speaking on the sidelines of a recent MRT seminar, city-owned project operator PT MRT Jakarta'€™s construction director, M Nasyir, explained that the tunnelling would involve four giant tunnel-boring machines (TBMs), which would excavate tunnels between 12 and 24 meters underground. Each machine is 3 m in length and 6.7 m in diameter.

'€œCompared with Singapore or Kuala Lumpur'€™s geological characteristics, Jakarta is less complicated because our city does not have as many rocks as they do. We ordered TBMs, which suit our geological condition,'€ Nasyir said, adding that the machines were designed to limit the disturbance to the surrounding terrain.

The tunnelling process of the 6-kilometer underground section is expected to be completed by the end of 2016, as the machines will excavate tunnels at a speed of 8 m a day.

Kazuya Osako of Shimizu Corp., a project manager for the Bendungan Hilir to Senayan section, said he was confident about the quality of TBMs to be used in Jakarta.

'€œWe have chosen very good machines for the Jakarta MRT project,'€ Ozako said, adding that the biggest challenge faced by contractors was not technical issues but the lack of experienced construction workers. '€œWe have to train the workers from zero,'€ he said.

Also speaking at the seminar was Singapore Land Transport Authority (LTA) director Chang Kin Boon, who recounted his experience diverting the Singapore River to make way for the construction of a new MRT line.

'€œThe Singapore River is one of our main tourist attractions and one of our main sources of water, so we had to carry out the project while maintaining the quality of the water by installing turbidity curtains prior to the demolition,'€ he said.

The Singapore River diversion project began in February 2012 and was completed in July 2014.

In Jakarta, MRT project contractors have had to contend with a water canal in the Dukuh Atas area, as well as a water pipe in the Bendungan Hilir area.

Shigeo Hanaki, the project manager for the HI traffic circle to Dukuh Atas section, revealed that his team would build the Dukuh Atas station 24 meters underground, below the canal.