Project Overview

TAG Advisory was engaged by the Public Transport Authority of Western Australia (PTA) to provide comprehensive cost estimation services for the City West Station project, a significant rail infrastructure upgrade comprising of two phases. Phase One involves replacing and raising the existing Sutherland Street Rail Bridge with temporary track and rail systems, whilst Phase Two encompasses a new station with underpass, structures, retaining walls, grade-separated Principal Shared Path and integrated rail systems. The engagement spanned from feasibility through to Project Definition Plan (PDP) development, requiring sophisticated cost management as the project evolved to meet funding constraints.

Key Challenges

The project faced significant budget and funding constraints that necessitated scope refinement and phased delivery strategies. Initial combined Phase One and Two estimates exceeded available funding, requiring innovative approaches to maintain project viability whilst delivering essential safety and operational improvements.

Constructability whilst maintaining rail services presented substantial complexity, with numerous possessions required to construct works whilst limiting operational impacts. The need to maintain existing at-grade pedestrian level crossings until safe alternatives were available added urgency to finding affordable interim solutions.

Technical challenges included integrating new structures with operational rail infrastructure, managing extensive utility relocations, coordinating with adjacent developments, and addressing community accessibility requirements throughout construction phases.

Methodology and Approach

TAG Advisory implemented a flexible, iterative approach to cost estimation responding to evolving project requirements. Initial services included preparing a comprehensive Class 5 Cost Estimate for combined Phases One and Two following PTA Project Cost Estimating Guidelines and Australian Government Cost Estimation Guidance.

When budget constraints emerged, the team worked collaboratively to refine scope and identify value engineering opportunities. Phase One scope was amended to include construction of an underpass, enabling removal of existing at-grade pedestrian level crossings and addressing critical safety requirements within available funding.

Key activities included:

• Continuous cost review as scope evolved
• Development of estimates ranging from Class 5 to Class 3 as design progressed
• Participation in Value Management Workshops with PTA and consultants
• Preparation of presentation materials for stakeholder engagement
• Quantification of project risks and opportunities

The October 2025 Class 3 Cost Estimate for Phase One provided robust support for the PDP submission.

Outcomes and Value

TAG Advisory's flexible approach enabled the City West Station project to progress despite funding challenges. The initial combined estimate informed strategic decisions about project phasing and priority setting. Through collaborative value engineering and scope refinement, Phase One evolved to address critical safety needs whilst remaining within funding parameters.

The Class 3 Estimate provided confidence for PDP approval, establishing clear cost parameters for construction procurement. Risk quantification enabled appropriate contingency allocation, whilst opportunity identification supported ongoing value management.

Conclusion

The City West Station project demonstrated TAG Advisory's ability to provide adaptive cost advisory services for complex rail infrastructure facing funding constraints. By maintaining technical rigour whilst enabling flexible scope development, TAG Advisory helped the PTA navigate challenging budget limitations to deliver essential safety improvements and progress this vital transport infrastructure upgrade.