Stoked by their debut success with the timely completion of Kajang Line’s underground section, Gamuda Engineering found themselves pitted once more against the unique challenges of tunnelling in Kuala Lumpur’s notorious karstic limestone, abrasive granite regions, and complex geological interfaces.
Fresh from delivering Malaysia’s first metro with great success, tunnelling contractor MMC Gamuda KVMRT (T) (MGKT - a joint venture between MMC and Gamuda Berhad in which Gamuda Engineering is its subsidiary) has recently celebrated the completion of its tunnels on Putrajaya line; it is the second extension to the Klang Valley Mass Rapid Transit. The scope of work includes 13.5-km of twin bored tunnel (internal diameter of 5.8-m), 11 underground stations, and other ancillary structures. A total of 12 tunnel boring machines (TBMs) were deployed, out of which 8 were variable density TBMs, and 4 were Earth Pressure Balance TBMs.
At first glance, there are many striking facts about the project. The alignment falls within some of the capital city’s most prime locations, crossing high density neighbourhoods, high-rise buildings, and public infrastructures. What’s more, the geological profile of the region is heterogeneous, further complicating the mining and deep excavation works required for the shafts. The geology includes Kenny Hill formation and Kuala Lumpur limestone—similar to that of the previous job—plus a particularly abrasive granite region, new to the tunnellers this time around.
Considering that the varying geology itself poses a risk to tunnelling, a risk mitigation drive was established from the very beginning, where extensive ground treatment works, constant monitoring and use of innovative solutions (paired with the contractor’s intimate understanding of the ground gathered from their earlier experiences) were aligned to shape the success of the project.
Continued success of the Variable Density Tunnel Boring Machine
A common thread to the success of the KVMRT projects is the award-winning VD TBMs. Developed jointly with Herrenknecht to specifically address Kuala Lumpur’s Extreme V karstic limestone, the VD machine continued to prove its versatility and efficacy in the second line. In one instance where a particular 1.7 km-stretch crossed two distinct grounds, the tunnellers switched from Earth Pressure Balance mode to Slurry mode in a single VD machine with ease as they navigated from alluvium soil into mixed ground conditions of limestone and Kenny Hill alluvium. In contrast, a conventional method would have required more shafts to be built and more machines deployed to complete the job.
Says Ng Hau Wei, Head of Tunnels, Gamuda Engineering, “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.”
World’s first Autonomous Tunnel Boring Machine
MGKT continued to push the envelope in pursuing tunnelling technologies, ultimately launching the world’s first autonomous tunnel boring machine. A shared vision of its leaders, the ATBM aspires to achieve a level of automation and digitalisation that will make tunnelling operations simpler and safer.
Typically, tunnelling operations tend to be labour intensive while, (at the same time) requiring attention to thousands of data points in real time. Seeing that there were plenty of avenues to modernise the sub systems of a TBM (steering, excavating, etc), MGKT developed a control algorithm that aggregates and analyses these data to deliver superior performance with faster response times, unbiased decision making and improved accuracies, resulting in overall safer operations.
Project: Klang Valley Mass Rapid Transit (KVMRT) Putrajaya Line
Location: Kuala Lumpur, Malaysia
Main contractor: MMC Gamuda KVMRT (T) SDN BHD
Scope of Work: 11 underground stations, complete with architectural and M&E services with escape shafts, all entrances, vent buildings at each station, tunnel portal structures, park & ride facilities, external works, roadworks, street lighting and landscaping, utility diversions, building protection works and temporary launch shafts for tunnelling. This is part of a larger scheme spanning 52.2km of MRT network connecting satellite towns of the Klang Valley to the city’s centralised business districts.
A large impetus behind the development was the shortage of mechanised tunnelling expertise in the local scene. With the ATBM, a world of possibilities has been opened up, reducing the menial and manual aspects of the job and elevating precious manpower into higher level tasks and oversight. By extension, a Tunnelling Command and Control Centre (TC4) was set up, where tunnellers can now monitor multiple TBMs remotely, thus enhancing communication and collaboration. The ATBM has been recognised by the New Civil Engineer society and International Tunnelling and Underground Space Association for its ground-breaking potential and has proven itself with over 9-km of tunnel successfully built in the Putrajaya line.
Project-wide Digital Transformation
In fact, a distinct feature of the project is the strategic roll-out of digitalisation initiatives unlike any before in Malaysian construction. In view of the overwhelmingly large volume of information transaction and construction activities happening daily across 17 construction sites, involving hundreds of staff, consultants, subcontractors and players, it only makes sense to wield the benefits of technology to streamline all workflows. Some examples of MGKT’s in-house solutions are:
The Project GIS (Geographic Information System) Portal: A web-based platform that grants a bird’s eye view of project site survey models. These surveys were developed using drone-captured photographs pinned with GIS applications. The Portal strengthens and informs decision-making processes by providing visualisation of these sites in their localities, granting context and a sense of proportionality. Even staff based overseas are now able to review site activities virtually and identify potential construction or temporary work-related issues in a timely manner, via the Portal.
Viewpoint Field View™ : A common data environment database that has taken field documentations for quality, safe, project delivery, closeouts and commissioning unto a Cloud, while simply using offline based mobile applications for input. Field View enables easy tracking, access and sharing of large quantities of project documents, ultimately offering the benefits of data analytics and security to boost project synergy
BIMAR (Augmented Reality in Building Information Modelling): An AR application for site inspection that allows real-world visualisation of 3D building designs through a mobile device. A first such in the industry, the app was developed in-house using Unity and Apple software development kits. A crucial key to the success of BIMAR is the accurate Building Information Modelling (BIM) renderings established early in the project and hosted on a reliable Cloud system. These were, in fact, BIM Level 2 certified from the British Research Establishment, a rare achievement from a contractor’s standpoint. BIMAR has radically enhanced the quality and safety aspects of overall operations with interactive and tangible means of visualisation, thus enhancing cross-collaboration and yielding efficient and meaningful outcomes to the business.
Success Despite Unforeseen Circumstances
It is noteworthy that these grassroot initiatives were successfully rolled out despite a chain of national affairs that had impacted the mega infrastructure project to a great extent. In late 2018, at almost halfway through the construction progress, an austerity drive by a newly elected government led to a change in the overall KVMRT project cost and contract. The project budget was slashed by 8.82 billion Malaysian Ringgit and converted into a turnkey model, resulting in major shifts in the organisational structure and work scope. Some of the major modifications affecting the underground section include the deferred opening of two stations (which were converted into shell and core stations), and rationalisation of architectural, electrical, and mechanical system works.
Another unforeseen incident was the onset of the Coronavirus-19 pandemic. When the country went into lockdown, 8 TBMs were already mining underground. To safeguard staff and workers well-being, numerous control measures and reconfiguration (both at worker’s residential and working spaces) were swiftly devised and implemented to allow essential construction works to proceed. Considering the far-reaching impact of these incidents (to name a few), on the project and its people, it is no mean feat for MGKT to deliver the tunnel completion with no compromise in safety, quality or schedule.
The entire Putrajaya Line is on track for full opening by January 2023, and Gamuda Engineering is ready to move on to other complex tunnelling projects, be it in Malaysia or elsewhere. Says Gusztáv Klados, a leading tunnel specialist with up to 50 years of industry experience, describes the phenomenal growth of GE with whom he has been with for almost 20 years. “Once we were awarded the construction of 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. In fact, it is with such capabilities and commitment to the task, that the VD TBM, was developed to tackle the challenging geology of the Kajang line. Our technical knowledge is convertible … there will be other places where we have an opportunity, and we will have a good chance of getting jobs.”
Contributed by Joyce Shamini Rajendran, Specialist Writer at MGKT