Project Overview

TAG Advisory was engaged by Main Roads Western Australia to provide independent cost estimation services for the Canning Bridge Bus Interchange project, a crucial component of Perth's integrated transport network enhancement. The engagement involved preparing a comprehensive 5% Concept Design Class 5 Cost Estimate to establish robust budget parameters for this significant public transport infrastructure upgrade aimed at improving multimodal connectivity and passenger experience.

Key Challenges

The project faced considerable challenges from evolving design scope and recent cost pressures that significantly impacted budget requirements. The dynamic nature of the design development process required continuous cost assessment as the project scope evolved to meet stakeholder requirements and technical constraints. This evolution created complexity in maintaining cost certainty whilst accommodating necessary design refinements.

Post-COVID market conditions introduced substantial cost escalation across all construction categories, requiring sophisticated analysis to ensure estimates reflected current market reality. Materials, labour and specialist subcontractor costs experienced significant inflation, whilst supply chain disruptions added delivery risk premiums that needed careful quantification and management.

Methodology and Approach

TAG Advisory implemented a structured approach to develop the Class 5 Cost Estimate. The methodology encompassed detailed quantification of all project elements including civil works, structures, pavements, drainage, utilities relocations and passenger facilities.

Key estimation activities included:

• Benchmarking against comparable interchange projects
• Current market testing with contractors and suppliers
• Detailed quantity take-offs from concept drawings
• Development of rates incorporating recent cost pressures
• Integration of project-specific delivery constraints
• Risk assessment and contingency allocation

The team maintained close engagement with design consultants to understand scope evolution and its cost implications. Regular cost reviews enabled proactive identification of budget pressures and opportunities for value management, ensuring the estimate remained aligned with project objectives despite scope refinements.

Outcomes and Value

TAG Advisory delivered a comprehensive Class 5 Cost Estimate that provided Main Roads Western Australia with clear understanding of project costs incorporating current market conditions. The independent estimate established a credible budget baseline for project approval and funding allocation, whilst identifying key cost drivers and risks requiring management through subsequent design phases.

The structured approach to addressing scope evolution and cost pressures enabled informed decision-making regarding design options and project staging. Clear documentation of assumptions and market conditions provided transparency for stakeholders and established foundations for future cost management.

Conclusion

The Canning Bridge Bus Interchange project demonstrated TAG Advisory's capability to deliver robust cost estimates under challenging conditions of scope evolution and market volatility. By providing independent, market-informed cost advice that addressed both design development and cost pressures, TAG Advisory enabled Main Roads Western Australia to progress this important transport infrastructure project with confidence in budget parameters and risk understanding.