Phase 0 ~$235M/km at current rates falling to ~$146M/km at volume. Two pylon designs locked: Design B (37.5m) for Phase 0.1, Phase 0, and all spurs; Design A (50m) for Phase 1, 2, and 3 with full continental water conduit. Stage 1 freight viaduct alone generates revenue from Month 20.
The SBC costing model uses three engineering tiers. Design A (full spec): $800–1,200M/km — the 50m pylon with full continental water conduit, used on Phase 1/2/3 inland transcontinental sections. Design B (standard): $250–350M/km — the 37.5m pylon with 1m water pipe, used on Phase 0.1, Phase 0, and all spurs. Phase 0 (proof of concept): blended cost ~$235M/km at current rates, falling to ~$146M/km at volume manufacturing. Stage 1 freight viaduct alone is ~$119M/km current / ~$74M/km volume — revenue from Month 20 of construction.
Phase 0.1: Newcastle → Muswellbrook spur, 111 km, follows existing Hunter rail, 15.1° max slope (existing reality). Phase 0: Melbourne–Brisbane spine, 2,410 km, 0.8° max slope. Phase 1: first transcontinental segment. Phase 2: continental expansion. Phase 3: full transcontinental network. Sequential phases follow strict revenue-funded order.
Two spur programmes operate in parallel with the continental phases. Phase 0-2: east coast spurs. Phase 0-3: second-wave spurs including the Melbourne–Adelaide segment (665.51 km, 6° max slope across the Adelaide Hills escarpment). Adelaide and Melbourne both promoted to double-junction status. Seven of eight Australian capital cities directly network-connected at completion.
The SBC is a single multimodal viaduct. Every kilometre carries freight + maglev passenger + HVDC + services (water, gas, fibre). Four revenue streams from one structural asset. This is what makes the unit economics work — and what makes the inland Phase 0 route defensible against a 1.85× crow-flies ratio: the spine serves three capitals, an entire farming corridor, and the Wellcamp hub on one set of pylons.
No infrastructure in Australian history generates revenue before completion. The SBC does. Month 20: Stage 1 freight access charges begin on completed segments. Month 24: HVDC backbone energised, $4–6B/yr from Day 1. Month 36: gas and fibre revenue begin. Year 3: total annual corridor revenue exceeds annual construction cost — the SBC funds Phase 1 from Phase 0 revenue. No further bond issuance required from this point.