From built to open: how testing and commissioning works, and who does it

When a major project reaches construction completion, the work does not stop — it changes hands. A smaller, highly specialised team takes over to prove that every system works on its own, then with everything around it, and then under real operating conditions. That is testing and commissioning, and on a new railway it typically runs for around two years.

The Cross River Rail Delivery Authority puts its own testing program at about two years, in line with Sydney Metro, Melbourne's Metro Tunnel and London's Crossrail. It is a planned phase with its own scope, its own people and its own program — not slippage — and it is the reason a construction completion date and an opening date are usually two different dates.

Here is what the phase involves and who does the work, using Australian projects that are in it now or have just come through it.

The projects at a glance

What testing and commissioning involves

Commissioning means systematically checking and integrating each system so that it runs safely, reliably and as designed before it enters service. Cross River Rail describes four stages, and they are a good template for any rail project:

1. Equipment testing ("build and test") — each installed component is checked on its own: signalling, ticketing, overhead wiring, power supplies, escalators, CCTV.
2. Integrated testing — proving the parts work together. This is where dynamic testing happens: trains run through the tunnels and stations, starting with single trains at low speed and building up to multiple trains under typical network conditions.
3. Operational readiness — running trains to a real timetable without passengers, training staff, and rehearsing critical scenarios such as evacuations, emergency ventilation and fire suppression, including test days where volunteers play the part of passengers.
4. Passenger operations — limited first services, built up gradually over six to nine months until the line reaches its normal "steady state".

On rolling stock, there is a step before any of that: static testing, where a new train sits stationary while technicians confirm its onboard systems are powered, connected and working correctly. Once it passes, the train moves on to dynamic testing on the line.

Who does the work

The commissioning phase draws on a different mix of skills from the construction phase:

• Testing and commissioning managers and engineers, who plan the test sequence, write the procedures and record the results.
• Systems specialists in signalling and train control, communications and ICT, CCTV and control systems.
• Electrical and instrumentation technicians, who energise power supplies and building services and check them under load.
• Mechanical and HVAC commissioning technicians — on an underground station, that includes tunnel and station ventilation fans and dampers.
• Lift, escalator and platform screen door specialists.
• Independent certifiers, who witness key tests.
• The operator's own people — drivers, controllers and station staff — who train on the new asset during operational readiness.
• On process plants such as desalination, process engineers and water quality specialists.

Rail

Cross River Rail, Brisbane: testing under way

By March 2026, with major civil construction nearing completion, Cross River Rail was moving into its testing and commissioning phase. UGL — working alongside Pacific Partnerships and CPB Contractors in the Pulse consortium, which is delivering the tunnel, stations and development package — reported in June 2026 that:

• at Boggo Road, the ventilation systems had been commissioned, with "bump testing" (briefly starting each fan) confirming correct rotation and operation, and damper testing under way
• building services, including HVAC and electrical, had been energised so they could be tested under operating conditions
• at Albert Street, ICT and CCTV systems were moving through pre-commissioning.

Earlier, at Roma Street in March 2025, the team completed Level 2 commissioning of the platform screen doors on platform 2 — 2,000 fault-free open-and-close cycles — before the Independent Certifier was invited to witness further testing.

A central job of integrated testing is the new European Train Control System (ETCS) digital signalling, which has to be proven to communicate correctly with both the trains and the Rail Management Centre. First passenger services are expected in 2029.

Who signs off. Under the Rail Safety National Law, a rail operator must be accredited by the Office of the National Rail Safety Regulator (ONRSR) before it starts railway operations, and must apply to vary that accreditation when its operations change. The Cross River Rail Delivery Authority says its testing program is what achieves the accreditation needed from safety regulators before the line opens to customers — the testing produces the evidence.

Metro Tunnel, Melbourne: the full cycle, completed

In July 2023, the first two test trains were driven into the twin nine-kilometre tunnels at South Yarra, one in each tunnel, stopping at Anzac Station. Over the following months testing moved from basic checks — trains lining up correctly with the platforms — to multiple trains at higher speeds, covering lifts, escalators, security, communications, lighting and platform screen doors, before trial operations with drivers and station staff.

The tunnel opened to passengers on 30 November 2025 with five new underground stations: Arden, Parkville, State Library, Town Hall and Anzac. On 1 February 2026 the "Big Switch" timetable fully integrated it into the network, adding more than 1,000 weekly services. That is about two years and four months from the first test train to the first passengers — right in line with the two-year rule of thumb.

Gold Coast Light Rail Stage 3: first test tram to opening in nine months

On the night of 12 November 2025, the first tram ran on the new tracks between Broadbeach South and Miami North. Night-time testing with up to two trams followed from late November to mid-December to verify signalling, communications and station operations, with testing on the Miami to Burleigh Heads section in 2026.

Stage 3 opened to passengers on Sunday 9 August 2026 — a 6.7-kilometre extension with eight new stations, delivered by John Holland as GoldlinQ's design and construct contractor. An extension to a line already in service, it went from first test tram to first passengers in about nine months.

Sydney Metro – Western Sydney Airport: next in line

All track on the 23-kilometre, six-station line from St Marys to Bradfield was laid by June 2026, and work turned to fitting out the tunnels and viaducts ahead of introducing power and testing trains.

The first of 12 three-carriage trains, built by Siemens Mobility in Vienna, arrived at the end of June. It was unloaded at Port Kembla and trucked to Sydney Metro's stabling and maintenance facility at Orchard Hills for assembly and static testing, with dynamic testing on the line expected to begin later in 2026.

Services are expected in 2027; a firm date has not been announced. Sydney Metro has said it is in productive discussions with the head contractor, the Parklife Metro consortium, on a number of claims and design modifications, with the aim of getting services running as soon as possible. In the meantime, Transport for NSW's free WSI Link shuttle connects St Marys station with the airport every 30 minutes from the first passenger flights until metro services start.

Aviation: Western Sydney International Airport

Major construction at Western Sydney International (Nancy-Bird Walton) Airport was completed in June 2025 — the terminal, the airside package including the 3.7-kilometre runway, and the landside roads, car parks and utilities. The airport then moved into operational readiness: testing its systems and preparing for passengers and freight.

After a series of cargo trial flights, the first commercial freight flight departed on 27 July 2026. Passenger flights begin on 25 October 2026, following what the NSW Government has described as seven years of construction and a year of testing — about 16 months from the end of major works to the first passenger.

Energy: Snowy 2.0

Snowy 2.0's power station sits about 800 metres underground at Lobs Hole and will house six reversible pump-turbines, supplied by Voith Hydro, with a combined capacity of 2,200 MW. Snowy Hydro's delivery partner is the Future Generation Joint Venture.

Snowy Hydro is targeting first power in the second half of 2027 and commercial operation of all six units by December 2028, and its May 2026 factsheet says the project is on track for that December 2028 date. The gap between the two milestones is the commissioning window: the units are brought into service progressively, and because each one both generates and pumps, each has to be proven in both modes before it joins the market.

Water: Alkimos and Eyre Peninsula

Alkimos Seawater Desalination Plant, WA

The plant is being built by the Alkimos SeaWater Alliance — Water Corporation, ACCIONA and Jacobs — and is due to be fully operational by mid-2028, initially supplying 50 billion litres of drinking water a year.

The water it produces will travel through a separate project: a 33.5-kilometre trunk main, 1.6 metres in internal diameter, being built by the Alkimos Pipeline Alliance of Water Corporation, Georgiou Group and DM Civil. More than 17 kilometres had been constructed by June 2026, and it is due for completion in 2027, connecting the plant via Carabooda Tank, the future Nowergup Tank and Wanneroo Reservoir to Perth's Integrated Water Supply Scheme.

So the pipeline is scheduled to be ready ahead of the plant it serves. Process commissioning on a desalination plant means bringing pre-treatment, the reverse-osmosis membranes and the brine outfall into stable operation and demonstrating water quality — chemistry and process engineering as much as construction.

Eyre Peninsula Desalination Plant, SA

At Billy Lights Point, SA Water's plant is being built by ACCIONA, with McConnell Dowell on the marine works and Leed Engineering on the transfer pipeline. By September 2026 major equipment was installed on the plant site and electrical works were nearly complete. Hard granite beneath the seabed has slowed the marine tunnelling, and SA Water is updating the late-2026 first-water target with its contract partners; it says the region's drinking water security is not affected.

What it means for the industry

A different workforce, for a longer stretch

Construction employs a large workforce for a defined period. Commissioning employs a much smaller, more specialised one, often for a year or more — the roles listed above, plus the subcontractors who return to close out defects. For specialist firms, it is a distinct market with its own skills and its own demand.

Retention and defects run through this phase

Defects liability periods and retention releases are usually tied to completion milestones, and on a long commissioning phase those milestones can fall well after the main crews have left site. Contracts differ, so it pays to check where your own obligations end. This is general information, not advice on any particular contract.

Integration is where the testing effort goes

Systems designed and installed by different teams have to work together for the first time during integrated testing, and the issues found there are often at the interfaces between them. That is why signalling and train control — which touches the trains, the track and the control centre — gets so much attention, as Cross River Rail's focus on ETCS shows.

Openings often come in stages

Cross River Rail reopened a rebuilt Rocklea Station on 8 July 2024 — the third station rebuilt for the project, after Yeronga and Fairfield — years before the tunnel opens. On the Gold Coast, Coomera Connector Stage 1 North opened to traffic on 2 December 2025 while construction continues on the Central and South packages. And the Metro Tunnel opened with passengers on 30 November 2025 before its full timetable switched over on 1 February 2026. A project "opening" is often a sequence, and the headline date is usually the last of them.

How to read a project announcement

Three questions tell you more than the headline:

1. Is the stated date construction completion, or the start of service? On a new railway they can be around two years apart.
2. Does the asset need a safety accreditation before it operates? New rail operations do, and the testing program is what produces the evidence for it.
3. How many units, trains or process trains are being commissioned? Where they are brought into service progressively, the commissioning window grows with the number of them.

What to watch

1. Cross River Rail's integrated testing, including the ETCS signalling, on the way to first passenger services in 2029.
2. Dynamic testing on the Sydney Metro – Western Sydney Airport line, expected later in 2026, and a confirmed opening date.
3. Snowy 2.0's first power, targeted for the second half of 2027.
4. Completion of the Alkimos trunk main in 2027, ahead of the plant's mid-2028 start.
5. SA Water's updated timeframe for first water from the Eyre Peninsula plant.

The commissioning phase is where years of construction become a working railway, power station or water supply — and with Western Sydney International opening this month and several more projects entering testing over the next two years, there is plenty of it ahead.

Published 12 October 2026 · Updated 4 October 2026