Australia’s investment in rail infrastructure continues to reshape how our cities grow. At the same time, governments are encouraging more housing around established transport connections, with the National Housing Accord targeting 1.2 million new, well-located homes over five years from mid-2024.

In NSW, this shift is already visible through the Transport Oriented Development (TOD) Program, which is enabling greater housing density around selected metropolitan rail stations. As development moves closer to transport infrastructure, more buildings are being planned above, beside and within the influence of existing rail tunnels and corridors.

For developers, that proximity brings engineering considerations that may not be obvious at the outset. Development near a rail corridor may require a specialised Engineering Impact Assessment (EIA), alongside navigation of the rail authority approval process, to demonstrate that risks to critical transport assets and their safe operation and maintenance have been appropriately addressed.

Identifying these requirements early can save significant time, cost and coordination later in the project – particularly where the proposed works could introduce risks to the integrity, safe operation or ongoing maintenance of the rail asset.

Transit-oriented development

Australia’s major cities are increasingly concentrating growth around rail. In NSW, Transport Oriented Development (TOD) planning controls now apply across 25 precincts, encouraging higher-density housing within walking distance of train and metro stations. The accelerated precincts alone are expected to create capacity for nearly 60,000 new homes over 15 years.

The same pattern is evident elsewhere. Victoria is planning for more than 300,000 additional homes by 2051 across 50 train and tram activity centres. Brisbane’s Cross River Rail combines new underground rail infrastructure with urban development around major station precincts.

As development becomes denser around rail, the engineering interface becomes more complex. Building near a rail tunnel or corridor brings foundations, excavation, ground movement and construction methodology into closer interaction with operational transport infrastructure.

For developers, rail-related engineering requirements are therefore becoming an increasingly important part of early project planning.

The need for an EIA

An Engineering Impact Assessment (EIA) examines how a proposed development could affect existing or planned rail infrastructure. For projects near underground rail, impacts can include excavation, foundations, ground movement, groundwater changes, and construction loads on tunnels, stations, and other rail assets.

Depending on the project and its proximity to the asset, analysis may be required to predict how the proposed works will influence the surrounding ground and what those changes mean for the performance of nearby tunnels or other rail infrastructure.

Rail authorities use protection zones and engineering requirements to safeguard this infrastructure. For relevant developments, an EIA can demonstrate that proposed works will not adversely affect the structural integrity, safety or operation of rail assets. It also provides engineering evidence to support the authority review and approval process.

Beyond the completed development

The assessment also needs to consider temporary conditions during construction, not just the completed development. Excavation, temporary support systems, dewatering and construction staging can change ground conditions and loading before the permanent works are in place.

Identifying the requirement early is critical. Rail constraints can influence basement depth, foundations, excavation, shoring and construction sequencing. Addressing them during early design gives project teams more scope to respond and reduces the potential for redesign, additional assessment or approval delays later.

The multidisciplinary approach

An EIA sits at the intersection of the proposed development, the ground and the rail infrastructure it needs to protect. No single engineering discipline can provide the complete picture.

Building structural engineers assess the proposed development, including its foundations, basement structures and the loads it will introduce.

Tunnel structural engineers consider how those loads and potential ground movements could affect the existing tunnel structure and its capacity. Geotechnical engineers link the two, assessing soil and rock conditions, groundwater, and how excavation and construction may change stresses and movement through the ground.

These responsibilities are different, but the engineering is interconnected. A change to basement depth or foundation design can alter ground behaviour, which may change the predicted impact on a nearby tunnel. Similarly, geotechnical findings can influence foundation selection, excavation support and the structural analysis required for both the building and rail asset.

When these disciplines are delivered by separate consultants, each working to different scopes, programmes and assumptions, coordination becomes another layer of complexity. Information may need to pass repeatedly between teams, assumptions can become misaligned, and gaps between scopes may not emerge until later in the assessment process.

An integrated engineering team can simplify that coordination. Building, tunnel and geotechnical engineers can develop and test assumptions together, respond to design changes more efficiently and maintain a coordinated view of the development and rail asset. The result is an EIA in which the engineering is considered as a whole, rather than a series of separate assessments.

NSW planning requirements also recognise that impacts may need to be considered cumulatively. Where several activities or developments influence the same rail asset, their combined effects on structural integrity, safety and operation may need to be assessed.

Simplifying approvals

Development near rail can involve multiple layers of engineering, documentation and authority review.

An integrated engineering team can manage these requirements from early feasibility through detailed design and authority approvals. Instead of coordinating separate structural, geotechnical and rail consultants, clients have one team managing the critical interfaces between the development and existing infrastructure.

This provides clearer accountability, reduces scope gaps and allows design changes to be resolved across disciplines rather than passed between consultants.

BG&E’s structural, civil, rail and geotechnical engineering expertise combines with SYSTRA’s specialist rail operations, tunnel engineering and client-side project management expertise, providing an integrated team from initial assessment through detailed engineering and the approvals process.

For developers, this means fewer interfaces to manage, clearer accountability and less programme risk on complex development near rail infrastructure.

Engineering the interface

Development around rail is ultimately an interface problem: between new and existing structures, between the ground and the assets it supports, and between development objectives and the requirements of operational infrastructure. Managing those interfaces early gives project teams greater freedom to solve them through design rather than respond to them later as constraints.

Start the conversation

Planning a development above, adjacent to or within the influence of a rail corridor or tunnel? Speak with BG&E’s Buildings team about the engineering and approval requirements for your project. Together with SYSTRA, our integrated engineering capability can support your project from early feasibility through assessment, design and approvals.