Underground Floor Area · reported
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Reading listings, research log, and source-health evidence.
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Two-level coastal-artillery central facility blasted beneath Storholmen in the early 1950s, with 5,000 m² / 53,820 ft² of underground space, 1,200 m of tunnels, three heavy guns, filtered ventilation, command rooms, workshops, utilities and accommodation.
Underground Floor Area · reported
Start date not established
Published date and precision preserved
Unit-attributed from its source article
Functional recreation of the documented facility in Sweden using current construction methods and 2026 prices, preserving the documented capacity, protection, autonomy and redundancy. Ex VAT; excluding land, financing, remediation, classified mission equipment and data-centre hardware.
Provisional audited central concept screen; expected-risk calibration is pending. It is not yet a risk-adjusted expected cost.
Method, scope and confidence →111 photographs sourced from the original article, with captions where available.
Published, calculated and proxy dimensions are deliberately separated. Missing evidence stays visible instead of becoming zero.
Rock in place removed before bulking; the excavation-pricing quantity.
Internal airspace; not the amount of rock removed.
Blasted material after bulking; the haul and disposal quantity.
These cubic metres are not interchangeable.
Usable, floor or footprint area; the label is preserved because these are not always interchangeable.
Underground Floor Area · reported · Publisher articleRock in place removed before bulking; the quantity used to price excavation.
Reported facility floor/shelter area is used as the screening usable-area basis. Archetype cavern-envelope factor is 6.5 design m³ per usable m². · Prior model input reviewed by auditInternal air or chamber volume. It is not solid excavation without overbreak, access and support geometry.
No usable quantity in the reviewed source · Evidence gapBlasted material after bulking, or its handled mass. No swollen cubic metres are inferred when only tonnes are modelled.
Reported facility floor/shelter area is used as the screening usable-area basis. Archetype cavern-envelope factor is 6.5 design m³ per usable m². Mass uses an assumed Swedish hard-rock density of 2.65 t/m³. · Reviewed mass-handling modelLength alone is insufficient; a costable tunnel also needs width, height or cross-sectional area.
Tunnel Length Total · Publisher articlePublished chamber or arch geometry used to test volume and support assumptions.
No usable quantity in the reviewed source · Evidence gapRock surface requiring bolts, mesh or shotcrete, preferably measured in square metres.
No support-area quantity is published · Audited excavation scopeCounts and dimensions of access, transfer, utility and emergency interfaces.
Several emergency exits and protected access are reported; exact count is not stated. · Reviewed base modelCast inner structures and linings, kept separate from excavated rock and reinforcement mass.
Reported facility floor/shelter area is used as the screening usable-area basis. Archetype concrete factor is 1.2 m³ per usable m². · Reviewed base modelGroundwater, inflow, drainage, pumping and moisture-control evidence affecting construction and operation.
Water And Waste · Publisher articleThe headline answers the current replacement question. Historic cost, CPI and construction-index comparisons remain separate because they answer different questions.
Different specifications receive different estimates; they are not used as the upper and lower limits of one answer.
Preserves documented capacity, protection, autonomy and redundancy using current construction methods.
Requires a modern structural, fire, protection and supplier performance brief.
Requires IT load, cooling topology, grid capacity, redundancy and autonomy. Server hardware is excluded.
No representative facility construction cost selected
General purchasing-power comparison—not a construction quote
Broad BKI proxy—not a bunker-specific rebuild price
Scope lock. Functional recreation of the documented facility in Sweden using current construction methods and 2026 prices, preserving the documented capacity, protection, autonomy and redundancy. Ex VAT; excluding land, financing, remediation, classified mission equipment and data-centre hardware. Named two-level coastal-artillery rock battery beneath the 22-hectare island of Storholmen. The source directly reports 5,000 m² / 53,820 ft² underground area, 1,200 m of tunnels, three 15.2 cm gun wells, filtered protective ventilation, command and fire-cont…
Audit revision sweden-replacement-audit-2026.08.15. The central WBS below incorporates the 61-article review. The former deterministic low/base/high cases remain available only as sensitivities and revision history.
Direct works + owner / design / investigation + legacy concept contingency
Central quantities × current installed-rate screen.
Not yet probability-weighted. The current legacy concept contingency remains separate.
22% applied to the direct-work screen.
Raw model SEK 848.9m · rounded for Confidence D.
Transitional limitation. SEK 144,378,125 is still a blanket concept contingency, not probability-weighted expected risk. This is why the amount is labelled provisional. The audited fort rock WBS remains the central scope ledger.
No subject caveat recorded.
72/100 article-geometry completeness. Detailed source extraction is available in the original-article audit.
Confidence D · geometry completeness 72/100
Largest active lines in the audited central component schedule.
The workbook publishes one revised central schedule. Its prior low and high stress cases are retained only under sensitivities; no line-level probability distributions are implied.
Hydrogeology, drainage, pumping and moisture control · SEK 19,500,000
Hydrogeology, drainage, pumping and moisture control · SEK 19,500,000
Integrated testing, commissioning and public-safe documentation · SEK 6,000,000
| Change | Scope | Audited base | Quantity / rate basis | Provenance |
|---|---|---|---|---|
| Retained | 01Fort galleries and supported excavationCivil Rock | SEK 243,750,000 | 32,500 Solid Design m³ × SEK 7,500 / Solid Design m³Derived From Published quantity · Assumption rateReported facility floor/shelter area is used as the screening usable-area basis. Archetype cavern-envelope factor is 6.5 design m³ per usable m². | Existing archive WBS |
| Retained | 02Rock mass handlingMass Handling | SEK 8,612,500 | 86,125 T × SEK 100 / TDerived From Published quantity · Derived rateReported facility floor/shelter area is used as the screening usable-area basis. Archetype cavern-envelope factor is 6.5 design m³ per usable m². Mass uses an assumed Swedish hard-rock density of 2.65 t/m³. | Existing archive WBS |
| Retained | 03Concrete roofs, galleries and emplacementsStructural | SEK 42,000,000 | 6,000 m³ × SEK 7,000 / m³Derived From Published quantity · Assumption rateReported facility floor/shelter area is used as the screening usable-area basis. Archetype concrete factor is 1.2 m³ per usable m². | Existing archive WBS |
| Retained | 04Installed reinforcementStructural | SEK 13,650,000 | 390,000 Kg × SEK 35 / KgDerived From Published quantity · Assumption rateReported facility floor/shelter area is used as the screening usable-area basis. Archetype concrete factor is 1.2 m³ per usable m². Archetype reinforcement intensity is 65 kg per concrete m³. | Existing archive WBS |
| Retained | 05Support-space fit-out and utilitiesBuilding Services | SEK 60,000,000 | 4,000 m² / 43,056 ft² × SEK 15,000 / Usable m²Derived From Published quantity · Assumption rateReported facility floor/shelter area is used as the screening usable-area basis. Fit-out factor is 0.8 times the reference scale. | Existing archive WBS |
| Retained | 06Protection and resilient systemsProtection | SEK 60,000,000 | 3.33 Project × SEK 18,000,000 / ProjectAssumption quantity · Assumption rateOne protection package per 1500 usable m² / 16,146 ft², subject to a 1-package minimum. | Existing archive WBS |
| Retained | 07Entrances, exits and site interfacesSite And Access | SEK 24,000,000 | 4 Project × SEK 6,000,000 / ProjectClass Proxy quantity · Assumption rateSeveral emergency exits and protected access are reported; exact count is not stated. | Existing archive WBS |
| Retained | 09Civil emplacement packagesMission Civil | SEK 100,000,000 | 4 Emplacement × SEK 25,000,000 / EmplacementAssumption quantity · Assumption rateArchetype mission-package count. | Existing archive WBS |
| Added | R073Hydrogeology, drainage, pumping and moisture control | SEK 19,500,000 | 8% of supported-rock scope as a class-screening allowance | Class assumption — site investigation/RFQ required |
| Added | R074Integrated testing, commissioning and public-safe documentation | SEK 6,000,000 | 5% of MEP/protection/mission-system scope | Class assumption — commissioning plan required |
Active base WBS SEK 577,512,500 · owner/design and contingency are added in the scenario cards above · 12 removed rows across the archive remain visible as change history.
The three inputs most likely to move the current screen.
These deterministic stress cases simultaneously vary quantities, rates, scope allowances and contingency. They are not confidence intervals and no longer serve as the headline answer.
Links support a rate, scope boundary or method. Context-only sources are not represented as quotations.
Gryaab February-2024 long-tunnel benchmark: SEK 5,513/design m³ for excavation plus support. Low case is lightly currentized; base/high add small, constrained, non-repetitive bunker uncertainty.
Gryaab February-2024 long-tunnel benchmark: SEK 5,513/design m³ for excavation plus support. Low case is lightly currentized; base/high add small, constrained, non-repetitive bunker uncertainty.
Skanska's Ostlanken order value is SEK 240m for handling 2.0m tonnes of rock and 0.4m tonnes of soil, excluding options. The base is the observed blended benchmark; bounds are assumptions.
Public ready-mix material check only; installed underground rates require RFQ.
Public retail material check only; cutting, bending, fixing, waste and underground logistics require RFQ.
Public sources establish specialized tested products but not project prices.
Heavy coastal defence of Sundsvall and command of the local barrier battalion.
Heavy battery and underground central facility built.
B004Three 15.2 cm m/98 E guns from the armoured ship Äran installed in massive gun wells.
B008Battery first manned for a firing period.
B004Manned, trained and modernized as a heavy coastal battery.
B004,B006Operated principally through wartime-organization exercises.
B006Fire-control modernization to Arte 719 reported.
B004Operations ceased.
B006Facility decommissioned a few years after operations ended.
B006Decommissioned, stripped, sealed and later partly reopened; article documents water, rust and rock-safety hazards.
B006,B009,B011,B019,B021Dated Timrå Skrotrivningar marking records dismantling activity inside the power centre.
B01928 reviewed claims. Evidence locators resolve against the stored article hash or archived snapshot.
| Subject | Claim | Value | Date | Evidence | Certainty |
|---|---|---|---|---|---|
| milestone | Event | Heavy battery and underground central facility built. | early 1950s | B004 | Reported |
| milestone | Event | Three 15.2 cm m/98 E guns from the armoured ship Äran installed in massive gun wells. | 1952 | B008 | Reported |
| milestone | Event | Battery first manned for a firing period. | 1959 | B004 | Reported |
| milestone | Event | Fire-control modernization to Arte 719 reported. | 1973 | B004 | Reported |
| milestone | Event | Operations ceased. | early 1990s | B006 | Reported |
| milestone | Event | Facility decommissioned a few years after operations ended. | mid-1990s | B006 | Reported |
| milestone | Event | Dated Timrå Skrotrivningar marking records dismantling activity inside the power centre. | 1996-10-07 | B019 | Reported |
| lifecycle summary | Event | Manned, trained and modernized as a heavy coastal battery. | 1959–1970s | B004,B006 | Reported |
| lifecycle summary | Event | Operated principally through wartime-organization exercises. | late 1970s-early 1990s | B006 | Reported |
| lifecycle summary | Event | Decommissioned, stripped, sealed and later partly reopened; article documents water, rust and rock-safety hazards. | mid-1990s onward | B006,B009,B011,B019,B021 | Reported |
| quantitative observation | Island Area | 22 hectares | — | B004 | Reported |
| quantitative observation | Underground Floor Area | 5,000 m² / 53,820 ft² | — | B004 | Reported |
| quantitative observation | Central Facility Floors | 2 floors | — | B004 | Reported |
| quantitative observation | Tunnel Length Total | 1,200 m | — | B004 | Reported |
| quantitative observation | Island Dimensions | {"length":700,"width":400} | — | B004 | Reported |
| quantitative observation | Planned Measurement Stations | 8 stations | — | B004 | Reported |
| quantitative observation | Guns | 3 15 2 cm guns | — | B008 | Reported |
| quantitative observation | Annual Training Strength | 100–125 | — | B006 | Reported |
| quantitative observation | Wartime Exercise Strength | 300 persons | — | B006 | Reported |
| quantitative observation | Firing Range | 12–20 | — | B006 | Reported |
| technical system | Command And Fire Control | SLC, SPL, SBC, KPL, radar/optical measurement and later STRIKA 85 communications supported command and gunnery. | — | B016,B017,B018 | Reported |
| technical system | Air And Climate | Shock-wave valves, filters, dehumidifier, cooling compressor and fans supported filtered protective operation. | — | B013 | Reported |
| technical system | Power | Grid supply arrived by subsea cable; emergency generators originally served the cavern but were removed by article time. | — | B019 | Reported |
| technical system | Water And Waste | Deep-bore well, pumped wastewater and three-chamber septic treatment for the cavern. | — | B020 | Reported |
| technical system | Habitability | Large kitchen, dining room, medical room, accommodation and workshops. | — | B016,B020 | Reported |
| protection | Rock Cover And Blast Doors | Underground tunnels and central building were isolated by steel-surfaced, concrete-filled shock doors. | — | B004,B016 | Reported |
| protection | CBRN Air System | Filter plant and protective ventilation intended to permit operation in contaminated air. | — | B013 | Reported |
| protection | Multiple Emergency Exits | Several small exits carried breakout tools in case attack debris blocked egress. | — | B009 | Reported |