Subsea supply contract signed
Southern Cross, ASN and OMS signed the supply contract in June 2025, moving SX-TX beyond an uncontracted concept.
Subsea connectivity · FULL DEEP TRACKER
Southern Cross Tasman Express
A living evidence file tracking SX Tasman Express from contracted system design through manufacture, marine installation, landing, commissioning and commercial service—without treating 400Tbps design capacity as capacity already available.
SUPPLY CONTRACTED · TARGET 2028Auckland–SydneyCONTINUOUSLY MONITOREDUpdated 25 August 2026
DESIGN CAPACITY400 Tbps
FIBRE PAIRS16
PER-PAIR DESIGN25 Tbps
COMPLETION TARGET2028
WHY IT MATTERS
Strategic significance
Tasman Express is designed as a direct, high-capacity link between the Auckland and Sydney cloud regions and data-centre hubs. Its value is not just a 20-fold design-capacity comparison with the older 20Tbps Tasman Global Access system: real resilience depends on distinct shore landings and terrestrial backhaul, while commercial value depends on lit capacity, anchor customers, latency and accessible pricing.
CURRENT ASSESSMENT
A contracted cable project, not yet an operating route.
Southern Cross, Alcatel Submarine Networks and OMS Group signed the SX-TX subsea supply contract on 4 June 2025. The disclosed design is 400Tbps across 16 fibre pairs using open-cable architecture, with OMS leading marine installation and completion targeted for 2028. The reviewed primary sources do not yet establish completed manufacture, marine survey, shore landings, in-service date, exact delivered latency, lit capacity, anchor customers or commercial pricing.
The tracker’s central question is whether a contracted 400Tbps design becomes a physically diverse, low-latency and commercially used trans-Tasman route by 2028. Until landing and backhaul details are verified, capacity scale alone cannot prove resilience.
EVIDENCE GATES
What is confirmed—and what remains open.
400Tbps across 16 fibre pairs
ASN states the system will deliver 400Tbps of additional design capacity across 16 fibre pairs for Southern Cross customers.
Open cable system
The wet plant is designed to work with future generations of submarine line-terminal equipment rather than locking the system to one initial terminal generation.
OMS leads installation
OMS Group is contracted to lead marine installation with ASN, but the reviewed primary sources do not yet confirm cable-lay commencement or completion.
2028 completion
Southern Cross and ASN describe 2028 as the target. A target date is not a confirmed ready-for-service or first-traffic date.
Alternate Australian landing
ASN branching-unit technology can facilitate an alternate Australian landing, subject to demand and final design confirmation; it is not yet a committed second landing.
Exact landing and backhaul diversity
The project is described as Sydney–Auckland data-centre connectivity, but exact shore stations and terrestrial routes needed to prove physical diversity are not publicly reconciled.
Customers, lit capacity and latency
No reviewed primary disclosure names anchor customers, contracted Tbps, initial lit capacity, delivered latency or wholesale pricing.
CAPACITY RECONCILIATION
Do not treat unlike numbers as equivalent.
Future system capacity
A design figure for the complete 16-pair system. It is not current lit capacity, contracted traffic or capacity available before service.
Arithmetic design average
400Tbps ÷ 16 fibre pairs. This calculated average is useful for reconciliation but is not a disclosed initial channel plan.
Existing Tasman system design
Vodafone lists the operating 2,288km Tasman Global Access cable at 20Tbit/s total design capacity; SX-TX’s 400Tbps is therefore 20× on a design-to-design basis.
DELIVERY & OPERATING STACK
The layers behind the headline.
Developer and networkSouthern CrossSX-TX will extend the Southern Cross ecosystem, which already connects Auckland, Sydney, the Pacific and the US.
System supplierASNAlcatel Submarine Networks supplies the subsea system and open-cable architecture.
Marine installationOMS GroupOMS leads marine deployment with ASN; vessel schedule and cable-lay milestones remain to be disclosed.
Wet-plant design16 fibre pairsSpace-division-multiplexing scale supports future terminal upgrades; design capacity must not be confused with initial lit capacity.
Primary routeAuckland–SydneyThe planned direct link targets key data-centre hubs; exact shore-end and backhaul routes remain material evidence gates.
Optional branchAlternate Australia landingBranching technology creates an option, but the landing depends on demand and final design.
Commercial layerSouthern Cross customersThe supplier announcement confirms the customer channel but does not name anchor buyers or capacity commitments.
Operating milestone2028 targetCompletion, testing, RFS and first traffic must each be independently verified.
VERIFIED TIMELINE
Key milestones and status changes
- 2024Southern Cross advances desktop study and initial system planning for a direct trans-Tasman route.
- 4 Jun 2025Southern Cross, ASN and OMS sign the SX Tasman Express subsea supply contract.
- 2025 disclosureThe parties confirm 400Tbps design capacity, 16 fibre pairs, open-cable architecture and an optional alternate Australian landing.
- CurrentThe project remains in pre-installation delivery; public primary evidence for cable manufacture, marine-lay start and exact landings is still pending.
- 2028 targetThe project is scheduled for completion and Southern Cross says it is targeted to come online in 2028.
STAKEHOLDER MAP
Who shapes the outcome
- Southern Cross Cables Limited, project developer and network operator
- Alcatel Submarine Networks, system supplier
- OMS Group, marine installation lead
- Spark New Zealand, Singtel Optus, Telstra and Verizon as Southern Cross shareholders
- Auckland and Sydney data-centre and cloud-region operators
- Carriers, hyperscalers, content platforms, government and enterprise capacity buyers
- Australian and New Zealand marine, environmental and telecommunications authorities
- Landing-station, power, terrestrial fibre and maintenance providers
DEPENDENCIES
What must align
- Final route engineering and marine survey
- Cable manufacture, branching units and terminal-equipment delivery
- Marine permits, weather windows, vessel availability and installation execution
- Confirmed Auckland and Sydney shore-end facilities
- Physically diverse terrestrial backhaul into data-centre hubs
- Power-feed and submarine line-terminal commissioning
- Anchor demand, spectrum/fibre-pair sales and financing discipline
- System testing, acceptance and operational maintenance arrangements
RISKS & OPEN QUESTIONS
What is not yet resolved
- The 400Tbps design figure can be misreported as current or contracted capacity
- A 2028 completion target may move with manufacturing, permits, weather or vessel schedules
- A direct route is not automatically diverse if shore landings or backhaul share failure domains with existing cables
- The alternate Australian landing remains optional rather than committed
- No public anchor-customer, pre-sale or contracted-capacity evidence has been verified from primary sources
- Open-cable architecture preserves upgrade choice but does not guarantee low terminal cost or competitive wholesale pricing
- Demand may be concentrated among hyperscalers and major carriers rather than broadly accessible
- Sydney–Auckland capacity strengthens the North Island corridor but does not itself create a South Island international landing
- Existing TGA and Southern Cross capacity means economic value depends on price, latency, utilisation and redundancy—not capacity headline alone
CORE EVIDENCE REGISTER