11th October 2020 saw the last tunnel ring that makes up the 13.5km-stretch of the Klang Valley Mass Rapid Transit (KVMRT) twin bored tunnels finally completed. Part of a 52km alignment known as the Putrajaya line, it is the second extension to the first Kajang line, Malaysia’s first metro network designed to connect satellite towns to its capital city, Kuala Lumpur (KL).
The project, constructed by Gamuda Engineering (GE), required eight Variable Density (VD) TBMs, four EPBMs, 16,000 tunnel segment rings and thousands of workers to construct the 11 underground stations — doubling as TBM launch and retrieval shafts — and other ancillary structures.
GE has previously and successfully constructed the first section of the line, which consisted of seven stations and 9.5km of twin-tunnel, mostly through KL’s notorious karstic limestone. The Putrajaya Line’s tunnels though are deeper, with more complex geological interfaces between the Kenny Hill, KL limestone and even an abrasive granite region where frequent, almost daily stops were required to replace worn TBM cutting tools and carry out preventative maintenance.
Other than the more complex geology, the Putrajaya Line tunnels also traverse critical infrastructure, such as major railway lines, elevated transits, and GE’s previous projects, the Stormwater Management and Road Tunnel (SMART) and the Kajang Line tunnels.
Despite this, the entire Putrajaya Line is on track for full opening by January 2023.
Leading tunnel specialist, Gusztáv Klados, commented, “Once we were awarded the construction of the Line One (Kajang line) tunnels, we had to build on the capabilities of the people who were with the company and nurture local knowledge and talent,”
The Herrenknecht VD TBM, was developed to tackle the challenging geology of the Kajang line. Gamuda Engineering Head of Tunnels, Ng Hau Wei, added, “continuity of the project from SMART, to the Kajang line and now to the Putrajaya line definitely kept us in momentum, but it ultimately boils down to having the right set of people and the best machines.”
On the Putrajaya line, GE introduced the world’s first autonomous tunnel boring machine (ATBM). Dubbed ATBM, the system was plugged into 10 of the TBMs used on the Putrajaya line to boost overall productivity, safety and quality of tunnel construction using artificial intelligence.
“With the VD TBM, we could switch between multiple slurry and EPB modes with ease in a single drive. With the ATBM system, the possibilities are endless as we now have supervision over tunnelling parameters and operations for multiple machines simultaneously, at the speed and accuracy of a computer,” Ng Hau Wei said.
The ATBM has won two prestigious international innovation awards in 2019, namely the Technical Equipment Innovation of the Year Award at the 2019 International Tunnelling and Underground Space Association (ITA) Tunnelling Awards in Miami, Florida and the Innovation in Tunnel Excavation Award at the Tunnelling Festival Awards in the UK sponsored by the British Tunnelling Society.