Underpinning works - the process of strengthening a building’s foundations - presented a particularly complex challenge at the Clayton site on the Suburban Rail Loop (SRL) East project. With no margin for error and just one week to deliver this critical work, the project demanded absolute precision. It’s in moments like these that digital engineering becomes indispensable.
The SRL East tunnels will be constructed in close proximity to an existing underground support pier beneath the elevated rail line at Clayton. Critical underpinning works were required to strengthen this pier, ensuring the safe and continuous operation of trains on the existing line throughout construction and once services on the SRL East line commence from 2035.
The process begins by installing new underground pillars on either side of the existing support pier, then pouring a concrete support beam connecting the pillars. The weight of the elevated rail pier is then transferred to the new support. One of the tunnel boring machines (TBMs) will pass directly between these two new pillars.
With a tight deadline and no margin for error, the team used 4D modelling tool, ToBe Builder to develop a construction sequence 4D simulation of projects, providing the client an accurate view of the proposed works. The immersive detail that digital engineering provided gave the stakeholders complete confidence that underpinning works could be achieved in a short space of time and with complete accuracy.
CPB Contractors Digital Engineering Manager, Salam Taouk says, “With underpinning works, there is no room for on-site improvisation, especially with live rail operations continuing above. The constraints, close proximity to live rail infrastructure and the compressed timeframe meant that every step had to be thoroughly validated before construction commenced
This is where digital engineering played a critical role. Both temporary and permanent works, along with plant, equipment and people movements, were incorporated into the ToBe Builder platform. This allowed the team to collaboratively review site access, plant manoeuvring and workforce interactions, ensure all safety measures were in place, identify gaps in the construction sequence, and assess risks and opportunities for further optimisation.
The 4D construction sequence simulation enabled the team to work closely with stakeholders, visualise the methodology in detail, test risks early and align everyone on the agreed approach. That shared digital understanding gave the team confidence to deliver the works safely, accurately and within a very tight window.”
Leveraging a highly accurate construction sequence_4D environment, the team successfully completed the works in less than 90 working days. The works were delivered in accordance with the program, without incident, and required only six days of rail disruption. This outcome was made possible through extensive planning and close coordination between the design, digital engineering, construction teams, and stakeholder’s teams.
CPB Contractors is proudly delivering SRL East alongside our Suburban Connect consortium partners, Acciona and Ghella.