Last updated Friday, October 31, 2014 08:41pm

KUALA LUMPUR, May 28 — Progress on the highly anticipated MRT project is slightly ahead of schedule, with more than half of its tunnelling works completed, MRT Corp Chief Executive Officer Datuk Azhar Abdul Hamid said today.

“If you look at the progress of the MRT line one overall, as far as our plan is concerned, we are supposed to be at 42.78 per cent completion.

“Actual progress is 43.49, so we are slightly ahead of plan,” he told reporters at the MRT Corp office.

Azhar said that 56 per cent of tunnelling work has been completed, adding that one of the Variable Density Tunnel Boring Machine (TBM) is working at the most challenging area in the project around Bukit Bintang, where the Karstic Limestone area transitions to the type of underground underfill called the Kenny Hill Formation.

Progress on the highly anticipated MRT project is slightly ahead of schedule, MRT Corp CEO Datuk Azhar Abdul Hamid said today. — Picture by Choo Choy May Progress on the highly anticipated MRT project is slightly ahead of schedule, MRT Corp CEO Datuk Azhar Abdul Hamid said today. — Picture by Choo Choy May So far, three sinkholes have been reported in the Bukit Bintang area, with the one in front of an Audi showroom on Jalan Imbi as wide as 10 metres and 18 metres in length.

Director of Tunnels Blaise Pearce said of the 9.5 kilometres of the underground alignment for the MRT line one, 7.5 kilometres are in the Karstic Limestone area where there are cavities, cracks and caves.

He explained the sinkholes were caused when the TBM hits fractured rocks and “variable slurry”, which he likened to the texture of yoghurt or hand cream, instead of the normal slurry that is basically “dirty water”.

It would then be pushed to the road's surface, causing sinkholes, Pearce added.

The Bukit Bintang area is particularly challenging than the rest of the limestone area because of possible ground anchors that was left behind during the construction of the Pavillion shopping mall.

“We would have to cut them with the tunnel boring machine which it is capable of doing, but we would have to remove them manually, which means going into the TBM and keep it clean so it can function correctly and efficiently,” Pearce explained.

Several lanes in the tourist hotspot have been closed because of the challenges.

Of that, seven kilometres or 90 per cent have been completed and one of the TBMs is expected to complete boring through the limestone area by the end of July, he added. These seven kilometres are the southbound tunnel.

On top of that, Azhar said the northbound line from Semantan and KL Sentral has also been completed.

“We are on track to complete phase one of MRT line one by December 2016 as promised and we are scheduled to complete the whole 51 kilometres by July 2017, as promised.

“In terms of cost as far as he MRT project line one is concerned, for construction, we have not spent more than RM7 billion,” Azhar said.

The construction for the mega project is expected to cost RM23 billion.