KUALA LUMPUR: The construction of the twin MRT tunnels beneath Jalan Bukit Bintang has been completed with the breakthrough made by two tunnel boring machines (TBM) at the Pudu Shaft recently.
Mass Rapid Transit Corporation Sdn Bhd director of strategic communication and public relations Amir Mahmood Razak said Inai 1 TBM broke through on October 16 while Inai 2 TBM on October 21.
"The overall progress of the MRT project underground works stood at 68.5 per cent as at the end of September, while the overall tunnelling completion is 88 per cent.
"We have just two TBMs digging up from the Pudu Shaft leading to Pasar Seni. All tunnelling works are expected to be completed by the first quarter of 2015, but underground works will continue until December 2016," he told reporters at the MRT Pudu Launch Shaft site near here today.
MMC-Gamuda Head of Tunnelling Ng Hau Wei said the completion of tunnelling was very challenging due to the geology of the area.
"Jalan Bukit Bintang straddles two geological formation - the eastern end of Jalan Bukit Bintang sits above the Kuala Lumpur Limestone Formation while the western end is above the Kenny Hill Formation, the transition between these two formation is at the Pavilion area," he said.
Another challenge was the highest concentration of utilities, he said, adding that, however, the use of high precision engineering technology, including Variable Density TBM had mitigated the problem.
"Besides significantly reducing the incidence of sinkhole formation, it is able to convert from the slurry shield mode (when tunnelling through limestone formation) to earth pressure balance mode (when tunnelling through Kenny Hill Formation) and vice versa," he said.
The Sungai Buloh-Kajang MRT, covering 51 km, will run through the city centre, including 9.5 km underground.
There will be seven underground stations, namely KL Sentral, Pasar Seni, Merdeka, Bukit Bintang Sentral, Pasar Rakyat, Cochrane and Maluri.-- Bernama