The SBC Cost Breakdown

Phase-by-phase capital cost, with all assumptions named. This memo provides the engineering view of the SBC programme capital cost — phase by phase, every assumption labelled. The first of three companion economic memos: this one costs the build, Memo 20 covers the return, Memo 21 the without-SBC counterfactual.

1. Purpose and methodology

This memo costs the SBC programme phase by phase. It does only that. It is the first of three companion economic memos:

• Memo 19 (this memo) — what the programme costs to build.
• Memo 20 (forthcoming) — what the programme returns in revenue, jobs, exports, and avoided cost.
• Memo 21 (forthcoming) — what Australia spends in the same period if it does not build the SBC, on the fragmented set of programmes (desalination, nuclear, AEMO transmission, AUKUS, M-D buybacks, smelter bailouts, drought relief) that the SBC absorbs or obsoletes.

The three together make the complete economic case. This memo provides the foundation that the other two reference.

1.1 Design-maturity stance

All figures in this memo are at 10–15% design maturity. This is the same design maturity at which the High Speed Rail Authority submitted its Stage 1 business case to Infrastructure Australia in December 2024. IA's evaluation of that case (November 2025) explicitly stated: "it is currently not possible to make a confident assessment of the proposal's benefit-cost ratio." The HSRA case did not, however, document its assumption set at this level of detail.

The methodology stance of this memo is the opposite. Transparent assumption documentation is not a weakness — it is the precondition for credibility. Every line item below is labelled with one of four confidence grades:

• Locked — sourced from the MMC cost catalogue at multimodalcorridors.com/costs.html, where detailed unit-rate engineering has been completed. Pre-feasibility grade, ±30%.
• Working estimate — sourced from the Phase 0 Working Document Article 28 assumption register, where unit rates are derived from published comparable infrastructure but not yet through detailed MMC engineering.
• Under MMC scoping — flagged as an assumption made specifically for this memo to produce a complete cost picture, with the basis stated explicitly. To be locked in subsequent MMC engineering work.
• Public benchmark — sourced from comparable public infrastructure projects (Inland Rail, Sydney Metro, AEMO ISP, Snowy 2.0) where MMC has not yet produced its own unit-rate work.

A consolidated assumption register sits at §9 of this memo, naming every assumption that materially affects the totals.

1.2 What this memo costs

The capex breakdown covers the physical SBC corridor build — the elevated multi-modal viaduct, the services that ride on it, the stations and interfaces, and the foundation civil works.

It does not cover:

• Alice Hub — costed separately at $65–133 B (PHES generation, MMC-VA trunk aqueduct from northern catchments, MMC-VD finger viaducts to individual rivers, pump stations along the trunk, AI campus and southern distribution head works). See Memo 5 — Alice Hub: The Continental Water and Energy Engine, §11 Cost Breakdown. Added to programme rollup in §7 of this memo.
• Desert PV generation — capacity bought by long-duration PPAs from industry rather than built by SBC. Counted in the revenue model (Memo 20), not the capex model here.
• Sovereign manufacturing setup (rail mill, OCTG mill, megafactory precast facilities, maglev guideway plant) — industry-funded under sovereign-content mandates with SBC equity participation. Out of scope of this memo, in scope of Memo 20.
• AUKUS-repositioned defence allocation — sits inside the 3% GDP defence envelope (~$90 B/year), not inside the SBC capex envelope. Some manufacturing capacity is shared (covered in Memo 18 and Memo 20).
• Continuing operations and maintenance — covered in Memo 20.

Keeping these out of the capex memo prevents double-counting and keeps the corridor-build cost clearly visible.

2. Cost components and unit rates

Every kilometre of SBC corridor is the sum of four cost components: viaduct structure, services, install, and a per-corridor share of stations. Plus contingency on the lot.

2.1 Viaduct structure (LOCKED at MMC site rates)

The MMC cost catalogue at multimodalcorridors.com/costs.html publishes locked per-kilometre rates for each viaduct configuration:

Each of these rates is the sum of three layers: Structure (foundation, pylon, cap beams, deck, walkway), Services (the supports and brackets for what rides on the structure), and Install (field labour and plant). The detailed breakdown for each — material cost per module, install hours, plant rates — is on the MMC site cost pages.

Confidence: LOCKED at pre-feasibility grade, ±30%. Pre-feasibility means the engineering is sufficient to compare across designs and to size the programme. Detailed engineering and quantity surveying are required before any binding-grade cost estimate.

2.2 Services on the structure (WORKING ESTIMATES)

The MMC cost catalogue is in development for the services that ride on the viaduct structure. The per-km rates for track, maglev guideway, HVDC conductors, water pipes, fibre, and pumping are not yet locked at the MMC site. The MMC site states explicitly that each service-component cost page is "in development."

This memo therefore uses working estimates from the Phase 0 Working Document Article 28A assumption register. Each is labelled accordingly.

Confidence: WORKING ESTIMATE. These rates are honest pre-feasibility working numbers. The MMC engineering work to lock them is in progress.

2.3 Stations (UNDER MMC SCOPING)

The Stations cost page on the MMC site is currently a stub ("in development"). Detailed station unit-rate engineering has not yet been completed.

For this memo, stations are costed on the following working assumption:

Basis: working rates derived from comparable public infrastructure — Inland Rail intermodal hubs, Sydney Metro interchange stations, Brisbane Cross River Rail stations. Australian construction labour premium applied.

Confidence: UNDER MMC SCOPING. The per-station rates above are explicit working assumptions for this memo. Each station's actual scope (passenger volume, freight transfer capacity, intermodal connections) will vary and the detailed costing will follow from station-by-station design.

2.4 Contingency, escalation, and volume production

Three further line items apply at programme level:

• Contingency rate: 25–30% applied to corridor capex. Standard for infrastructure at 10–15% design maturity per AACE International Class 4 estimate guidance. The HSRA business case applied similar contingency at the same design maturity.

• Escalation: not applied within these figures. All numbers are in 2026 AUD. Real-terms escalation across a 15–20 year build will increase nominal totals; the comparative analysis vs HSRA, vs nuclear pathway, vs AEMO ISP, etc. is more robust when stated in real terms.

• Volume production effect: -38% Wright's Law reduction over the full 800,000 span programme (2.1 of the assumption register). Applied to subsequent phases, not Phase 0. Phase 0 is costed at current unit rates as the proving build; volume reductions apply to Phase 1, 2, 3 once the manufacturing scale ramps up.

3. Phase 0 — The spine

Route: Melbourne → Brisbane via the inland alignment. Distance: 2,284 km (provisional pending re-measure of the new inland-via-Bathurst/Dubbo alignment). Viaduct configuration: MMC-VB (dual-leg, two-level, full multi-service). Services carried: 3-track electrified freight + 2-track maglev passenger + HVDC arms + gas + hydrogen + water + fibre.

3.1 Phase 0 station list (LOCKED)

The Phase 0 spine stops at 18 stations from Melbourne to Brisbane:

Melbourne · Bendigo · Echuca · Shepparton · Benalla · Wangaratta · Albury · Wagga Wagga · Goulburn · Western Sydney Airport · Bathurst · Dubbo · Muswellbrook · Tamworth · Armidale · Warwick · Toowoomba · Brisbane.

Station classification for cost purposes:

• Major intermodal hubs (5): Melbourne, WSA, Muswellbrook, Toowoomba, Brisbane
• Intermediate freight + passenger stations (13): Bendigo, Echuca, Shepparton, Benalla, Wangaratta, Albury, Wagga Wagga, Goulburn, Bathurst, Dubbo, Tamworth, Armidale, Warwick

3.2 Phase 0 cost breakdown

Phase 0 indicative cost: $138 – $257 billion at current rates.

Phase 0 alone is the largest single capex line in the programme — because it is the proving build at current unit rates, before manufacturing scale brings down per-km costs for the continental phases. Subsequent phases benefit from the Wright's Law -38% volume production effect once 800,000 spans have been manufactured.

3.3 Reconciliation with the Phase 0 Working Document

The Phase 0 Working Document Article 27B states SBC Phase 0 cost ~$142 B current rates / ~$88 B volume production. This memo's figure of $138–257 B at current rates is consistent with the lower bound of that range but extends to a higher upper bound. The reason is that this memo applies the full upper-bound maglev guideway rate ($30 M/km × 2 tracks = $137 B for maglev guideway alone) which is the highest-uncertainty line item in the programme.

The two figures reconcile when read as follows:

• Lower bound ($138 B) — assumes the maglev technology-transfer deal succeeds (cost reduction from international rates).
• Upper bound ($257 B) — assumes no technology transfer deal and full international rates apply.
• Mid-point (~$197 B) — assumes partial cost reduction, the working assumption of the Phase 0 doc.

The maglev guideway cost is the largest single uncertainty in the programme. The technology-transfer negotiation is identified as a critical-path action in the Phase 0 Working Document (Action A99).

4. Phase 0 spurs (0-1 through 0-7)

The seven Phase 0 spurs extend the spine to additional regional centres, ports, and capital cities. Each is costed separately using the same component build-up.

4.1 Phase 0-1 — Hunter Valley spur (113 km)

Route: Newcastle → Maitland → Singleton → Muswellbrook Configuration: MMC-VB multi-modal Stations (LOCKED): Newcastle, Maitland, Singleton, Muswellbrook (4)

4.2 Phase 0-2 — Newcastle to Sydney Central (142 km)

Route: Newcastle → Watagans → Hornsby → Parramatta → Sydney Central Configuration: MMC-VC single-leg single-deck (passenger-only) Stations: Newcastle, Sydney Central confirmed; intermediates UNDER MMC SCOPING (assumed ~4–6 passenger-only stations along the 142 km).

Note: Phase 0-2 cost is dominated by maglev guideway (passenger-only spec). No freight track, no HVDC transmission backbone — these stay on the Phase 0 spine and the MMC-VB corridors. Water pipes are not part of the Phase 0 build at all — the continental water network arrives with Phase 1, 2, and 3 when Alice Hub and the central engine come online.

4.3 Phase 0-3 — WSA to Sydney Central (50 km)

Route: Western Sydney Airport → Parramatta → Sydney Central Configuration: MMC-VC single-leg single-deck (passenger-only) Stations: WSA, Parramatta, Sydney Central (3 confirmed). Likely 1–2 additional intermediate stations within urban Sydney UNDER MMC SCOPING.

Note: Stations dominate the cost on this 50 km spur — three major-hub stations at the endpoints plus urban Sydney intermediate stops carry more cost than the viaduct itself.

4.4 Phase 0-4 — Toowoomba to Port Douglas (1,645 km)

Route: Toowoomba → Brisbane connection point → Bundaberg → Rockhampton → Mackay → Townsville → Cairns → Port Douglas Configuration: MMC-VB multi-modal Stations: Endpoints confirmed (Toowoomba on Phase 0 spine, Port Douglas terminus). Intermediate stations UNDER MMC SCOPING — assumed ~8–10 stations along the corridor at coastal QLD regional centres (Bundaberg, Gladstone, Rockhampton, Mackay, Bowen, Ayr, Townsville, Ingham, Innisfail, Cairns).

4.5 Phase 0-5 — Brisbane to Port Macquarie (447 km)

Route: Brisbane → Gold Coast → Tweed Heads → Byron Bay → Lismore → Grafton → Coffs Harbour → Kempsey → Port Macquarie Configuration: MMC-VB multi-modal Stations: Endpoints confirmed. Intermediate stations UNDER MMC SCOPING — assumed ~5–7 stations.

4.6 Phase 0-6 — Melbourne to Adelaide (665 km)

Route: Melbourne → Ballarat → Horsham → Bordertown → Murray Bridge → Adelaide Configuration: MMC-VB multi-modal Stations: Endpoints confirmed. Intermediate stations UNDER MMC SCOPING — assumed ~4–6 stations.

4.7 Phase 0-7 — Canberra to Eden (250 km)

Route: Canberra → Cooma → Bombala → Eden Configuration: MMC-VB multi-modal (freight-priority spur to deepwater Pacific port) Stations: Endpoints confirmed (Canberra on spine, Eden terminus). Intermediates UNDER MMC SCOPING — assumed 2–3.

4.8 Phase 0 spurs total

Combined Phase 0 (spine + 7 spurs): 5,594 km, $341.7 – $637.8 B at current rates.

The Phase 0 spurs are heavily skewed by Phase 0-4 (Toowoomba–Port Douglas) — at 1,645 km it is more than half the total spur distance. The other six spurs sum to ~1,665 km and ~$105–197 B.

5. Phase 1 — First continental (6,775 km)

Routes:

• Phase 1 SBC #1 — Brisbane → Perth (3,519 km)
• Phase 1 SBC #2 — Darwin → Adelaide via Alice Springs (2,661 km)
• Phase 1-1 — Perth → Albany (595 km)

Configuration: MMC-VA continental (Big Bertha, five-level dual-leg, 50 m deck) for the two main continental corridors carrying the transcontinental aqueduct. MMC-VB for the Perth–Albany spur.

Stations: Endpoints confirmed. Intermediates UNDER MMC SCOPING per corridor — assumed station counts based on regional centres along each route.

5.1 Phase 1 cost build-up

For Phase 1 onward, volume-production effects begin to apply. The Wright's Law -38% reduction reaches its full effect after ~800,000 spans manufactured. Phase 0 (5,594 km × ~40 pylons/km = ~224,000 pylons) represents ~28% of programme volume; Phase 1 brings the cumulative total past ~50% of the curve. For this memo, Phase 1 is costed at a working -15% reduction from current rates, with full volume effects applied to Phases 2 and 3.

Note on MMC-VA vs MMC-VB cost effect: MMC-VA at $13.97 M/km is approximately double MMC-VB at $7.27 M/km — but it carries the full continental aqueduct (Design A 15.2 m × 9.6 m conduit) which the working doc identifies as delivering ~11,460 GL/yr per corridor. The cost premium is the price of the continental water transfer that makes the centre productive.

Alice Hub allocation: $65–133 B (see Memo 5 §11 for the breakdown) is most naturally allocated to Phase 1 since SBC #2 passes through Alice Springs and the head pond infrastructure and trunk aqueduct alignment follows the SBC #2 corridor build. Alice Hub is excluded from the corridor capex above but added at the programme level — see §7.

6. Phase 2 and Phase 3 — Network closure

6.1 Phase 2 — Northern corridors (5,416 km)

Routes:

• Phase 2 SBC #3 — Albury → Karumba (2,238 km)
• Phase 2 SBC #4 — Mackay → Port Hedland (3,178 km)

Configuration: MMC-VA continental for both (carrying continental aqueduct extensions).

By Phase 2 the manufacturing scale has reached full volume — Wright's Law -38% reduction applies.

6.2 Phase 3 — Network closure (5,413 km)

Routes:

• Phase 3 SBC #5 — Derby → Esperance (1,871 km)
• Phase 3 SBC #6 — Albany → Port Douglas (3,542 km)

Configuration: MMC-VA continental.

7. Programme rollup

Bringing every phase together:

7.1 Phasing — when each phase happens

The phases overlap. SBC #1 (Brisbane–Perth) can begin construction while Phase 0 spurs are still completing, because manufacturing capacity and crew availability scale across phases. This is part of why the gross capex figure is misleading on its own — it's a 20+ year programme, not a single-decision-now spend.

8. The honest qualifications

This memo is at 10–15% design maturity. Reading it as anything else would be a misrepresentation. The qualifications below sit at the front of any conversation about these numbers.

8.1 Maglev guideway is the dominant uncertainty

Maglev guideway accounts for $135–230 B of the gross programme capex at the upper bound — the single largest line item. The technology-transfer negotiation that brings this rate down from international ($65–160 M/km) to working ($15–30 M/km) is the highest-leverage commercial action in the programme. Without it, the upper-bound figures hold; with it, the lower-bound figures hold.

8.2 Stations are mostly under MMC scoping

Of the ~95 stations across the full network, only the Phase 0 spine list (18) and Phase 0-1 list (4) are locked. The remaining ~73 stations are working assumptions. Per-station rates are also working assumptions until the MMC Stations cost page completes. Station cost uncertainty is the second-largest line-item uncertainty after maglev guideway.

8.3 Continental water conduit (Aqueduct VA) cost is a working estimate

The MMC site Aqueduct VA cost page is in development. The $4–8 M/km working rate used in this memo is honest at pre-feasibility level but the MMC engineering work to lock the figure is pending.

8.4 Phase 0 distance is provisional

The Phase 0 spine distance is stated as 2,284 km pending re-measurement of the new inland-via-Bathurst/Dubbo alignment. Three earlier figures (2,290 / 2,401 / 2,423 km) exist in older documents. The corridor distance is a structural input to every cost line on Phase 0 — a ±5% re-measure changes the Phase 0 total by ±$7–13 B.

8.5 Foundation depth varies

All foundation costs above are at the MMC catalogue baseline depth (15 m for MMC-VB, 20 m for MMC-VA, 10 m for MMC-VC and VD). Real foundation depths will vary with geology — river crossings, floodplain sections, escarpment crossings will require deeper foundations and proportionally higher cost. The Blue Mountains escarpment crossing in Phase 0 (working doc Article 26) carries a $180–540 M premium across ~15 km that is allocated to the contingency line above rather than the structural line.

8.6 Currency, escalation, and discount rate

All figures are 2026 AUD nominal. Real-terms escalation across a 15–20 year build is not applied — for comparative analysis vs HSRA, vs the nuclear pathway, vs AEMO ISP transmission, the comparison is more honest in constant 2026 dollars. Memo 20 (revenue) will apply NPV discounting consistent with infrastructure-financing convention. Memo 21 (counterfactual) will use the same conventions for the alternative programmes.

9. Consolidated assumption register

Every assumption that materially affects the programme totals, in one register.

9.1 Distance assumptions

9.2 Unit-rate assumptions (viaduct structure)

9.3 Unit-rate assumptions (services)

9.4 Station assumptions

9.5 Programme-level assumptions

9.6 Excluded from this memo

10. What comes next

Memo 20 — The SBC Return on Investment will cover:

• Revenue streams per phase (freight tolls, maglev fares, HVDC transmission fees, water delivery, Asia export revenue, AI compute, manufacturing renaissance)
• Self-funding mechanics from Month 20 of Phase 0.1
• Jobs and Australian content (65–75% across the programme)
• Avoided cost (imports replaced, externalities avoided)
• Strategic value not monetised (defence sovereignty, regional integration, decarbonisation export)

Memo 21 — Without the SBC will cover:

• The fragmented set of programmes Australia spends on without the SBC (nuclear $300–600 B, AEMO ISP transmission $120 B+, desalination $122 B, AUKUS $368 B current structure, Snowy 2.0 + further pumped hydro, M-D buybacks continuing, smelter bailouts, drought relief continuing, housing crisis solutions that don't work because coastal-only)
• The counterfactual table — with SBC vs without SBC on the same time horizon and same outcomes
• The honest claim: the SBC is not a new spend. It is a redirect.

The three memos together make the complete economic case.

11. Bottom line

The SBC programme costs approximately $750 billion to $1,340 billion gross at current unit rates, at 10–15% design maturity, over a 20+ year build, across 23,200 km of continental network and the Alice Hub continental water-and-energy engine.

The lower bound assumes the maglev technology-transfer deal succeeds and the build benefits from volume-production rates on Phases 1, 2, and 3. The upper bound assumes neither.

This memo provides the engineering cost view — the corridor build, allocated phase by phase, plus the Alice Hub system (referenced to Memo 5 §11), every assumption named. It does not address revenue, offsets, or counterfactuals — those are the subjects of Memos 20 and 21.