Cross River Rail
When tunnelling threatened Brisbane’s busiest transit interchange, ADG engineered a solution that kept the city moving.
The Inner Northern Busway carries thousands of commuters daily through Roma Street Station. When Cross River Rail’s tunnel alignment passed near its foundations, the challenge was clear: protect critical infrastructure, maintain 24/7 operations, and deliver certainty to multiple government stakeholders. ADG developed a micropiled underpinning methodology that allowed tunnelling to proceed whilst the busway remained fully operational – delivering millions in cost savings and eliminating months of potential delays.
CONSTRUCTION VALUE
Capacity of hydraulic jacking system
Depth of tunnelling works below structure
Keeping Brisbane Moving
- Design underpinning works within an operational train and bus station with severe spatial constraints
- Maintain 24/7 busway operations throughout construction with zero service disruptions
- Limit differential settlement between columns to prevent structural damage
- Navigate complex stakeholder requirements across multiple Queensland Government authorities
Precision Engineering in Tight Spaces
- Develop micropiled foundation solution within extreme vertical and horizontal limitations
- Design innovative steel collar system to transfer loads from existing columns to new micropile foundations
- Engineer jacking system capable of correcting differential settlement during and after tunnelling
- Perform complex structural analysis to establish damage trigger levels for live structure
Multi-Agency Coordination
- Satisfy requirements of Cross River Rail Delivery Authority, Queensland Rail, and Department of Transport and Main Roads simultaneously
- Develop staged construction methodology acceptable to all administrative authorities
- Coordinate structural and geotechnical engineering disciplines to deliver integrated solution
Working alongside EDG Consulting, ADG developed a staged construction methodology that transformed a complex engineering and administrative challenge into an elegant solution.
Our approach centred on designing new permanent micropile foundations that could be installed whilst the busway remained operational. We engineered a system of temporary props jacked against the INB deck, allowing existing bridge piers to be carefully cut from their original pile foundations without load transfer issues.
The technical innovation lay in our steel collar design – a bespoke transfer system that connects the existing column superstructure to new micropile foundations via four 200-tonne hydraulic jacks nested in specially designed jacking pockets. This system doesn’t just support the structure; it actively corrects differential settlement caused by tunnelling 15 metres below, providing both immediate support and long-term adjustment capability.
ADG performed detailed structural analysis to establish precise trigger levels – the maximum permitted vertical displacement between neighbouring columns before damage occurs. This quantitative approach gave all stakeholders confidence in real-time monitoring and decision-making throughout construction.
The staged methodology we developed meant construction could proceed in manageable phases, limiting risk whilst maintaining the ability to adjust based on observed structural behaviour. Our local knowledge of Queensland’s regulatory environment and existing relationships with state authorities proved critical in navigating the complexity of works spanning multiple government portfolios.
The result?
A $3M saving in construction and material costs, elimination of indirect time delays, and most importantly – uninterrupted operation of critical Brisbane transport infrastructure whilst Cross River Rail’s transformational tunnelling works proceeded beneath.
Risk Mitigation
Detailed finite element modelling and geotechnical assessment informed our trigger level framework, providing quantitative thresholds for intervention throughout construction. Our staged approach allowed real-time monitoring and adjustment, ensuring structural integrity whilst maintaining operational continuity. The collaboration between ADG’s structural engineers and EDG Consulting’s geotechnical specialists created a comprehensive risk management strategy that protected both the existing infrastructure and the tunnel works below.
Innovation in Constrained Environments
Developing a micropiled underpinning solution that could be constructed within the spatial limitations of an operational transit centre presented a significant challenge. The steel collar and jacking system represents construction engineering adapted to extreme constraints – designed to be installed, operated, and adjusted within the existing structure’s footprint without requiring building modifications or service interruptions. The innovative jacking pocket design allowed for precision vertical adjustment whilst maintaining full load transfer capacity.
Collaborative Delivery
Success required seamless coordination between ADG’s structural team, EDG Consulting’s geotechnical engineers, CBGU JV construction teams, and three separate Queensland Government authorities.
Our local presence and established relationships turned potential administrative gridlock into collaborative problem-solving.
The real achievement was the combination of the permanent structural design, the structural engineering solution, the methodology and working with the geotechnical engineers to satisfy the requirements of Administrative Authorities and the Cross River Rail Joint Venture.
Let’s start the conversation.
When critical assets can’t stop operating and the engineering margins are tight, you need the home advantage. Let’s talk about your next transport infrastructure challenge.
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