WaiMAPWhitewell NPP – Bulgaria – Germany transmission corridor (demonstration)
Whitewell NPP area → Bulgaria → Bavaria — A 400 kV corridor of about 2,418 km screened with the WaiMAP line engines: three route alternatives on an open-data cost surface, three representative 10 km sections with spotting, sag-tension, quantities, optimum spotting and checks.
Purpose
Show how a developer, TSO planner or EPC bidder compares long-distance corridor alternatives and gets first quantities, costs and risks — before any survey.
Scope
Corridor screening and three representative 10 km sections (level ground). Not included: terrain profile (no DEM on the build machine), OpenStreetMap crossings, protected areas, submarine crossing design, substations, permits.
Technical challenges
- About 2,000 km across three countries and very different land use
- The Turkish Straits region: dense settlement and open water
- Large river flood plains (Danube basin and others)
- Keeping thousands of towers consistent: spotting, sag-tension and quantities at scale
Input data given to WaiMAP
Every input with its source and licence. Open atlas data load automatically; the rest was entered by hand.
| Input | Source and licence | How |
|---|---|---|
| Solar resource (GHI, PVOUT, air temperature) | Global Solar Atlas 2.0 (World Bank Group, data by Solargis) (CC BY 4.0) | automatic (atlas on the calculation server) |
| Wind speed at 150 m | Global Wind Atlas 3 (DTU, World Bank Group) (CC BY 4.0) | automatic |
| Population density 2025 | GHS-POP R2023A, European Commission, JRC (CC BY 4.0) | automatic |
| Built-up surface 1975–2030 | GHS-BUILT-S R2023A, European Commission, JRC (CC BY 4.0) | automatic |
| River flood depth, 100-year return period | JRC / Copernicus Emergency Management Service – GloFAS flood hazard map, 100-year return period (CC BY 4.0) | automatic |
| Terminal points and the waypoint in Bulgaria | entered by the user | manual input |
| Voltage, conductor, earth wires, soil class | chosen by the user (400 kV, triple Cardinal, 2 OPGW, medium soil) | manual input |
| Weights of the land classes | WaiLineMech ohl400 defaults | automatic, editable |
Automatic workflow vs manual input
| Step | Automatic / manual | Engine |
|---|---|---|
| Cost surface from open data | Automatic | build_demos.py → WaiLineMech land classes |
| Route alternatives | Automatic | WaiLineMech.routeAll (A* on 16 neighbours, penalised re-runs) |
| Representative sections — spotting and sag-tension | Automatic | WaiLineMech.design (IEC 60826 / EN 50341-1 style cases, CIGRE TB 324 change of state) |
| Optimum tower spotting | Automatic | WaiLineMech.optimise (dynamic programming, Mitra & Wolfenden formulation) |
| Quantities and cost (screening) | Automatic | WaiLineMech quantities + per-km cost model (lineCost, indicative EU defaults) |
| Checks and warnings | Automatic | WaiLineMech checks |
| Access roads and crossings | Runs in the app (not in this demonstration) | Corridor routing with OpenStreetMap, Logistics (in the app) |
Calculation steps — engines and methods
The results below are what the engines returned on 2026-10-13 06:00 UTC. Steps that need data the build machine did not have are marked and carry no numbers.
Cost surface from open data Automatic
EPSG:3035 grid, 2 km cells, 1284 × 1091 = 1,400,844 cells. Classes: open water where the Global Solar Atlas has no land data (×15), dense built-up ≥ 25 % (exclusion), settled (built-up ≥ 5 % or ≥ 400 persons/km², ×40), flood-prone (RP100 mean depth ≥ 0.3 m over the cell, ×3), open (×1) — the ohl400 weights of WaiLineMech.
- Share of cells: water 27.35 %, settled 3.85 %, dense built-up 0.19 %, flood-prone 17.57 %
- Not in this surface: slope (no DEM), protected areas, forests, road / rail / river / power-line crossings (OpenStreetMap) — they are added in the app
Route alternatives Automatic
Two legs (A → W, W → B) with the waypoint in Bulgaria; per leg: cheapest, least sensitive (land weights cubed) and shortest; alternatives separated by ≥ 15 km.
- Cheapest: 2,418 km (×1.046 of straight line), settled 34 km, flood-prone 122 km, water 2 km, 60 angle points
- Least sensitive: 2,703 km (×1.169 of straight line), settled 17 km, flood-prone 80 km, water 6 km, 61 angle points
- Shortest: 2,330 km (×1.008 of straight line), settled 108 km, flood-prone 479 km, water 40 km, 3 angle points
Representative sections — spotting and sag-tension Automatic
Three 10 km sections of the cheapest route, each starting 3 km before an angle point of the route (rule fixed before the run); 400 kV single circuit, triple ACSR Cardinal, 2 OPGW, medium soil. Angle points from the route geometry. Terrain profile: level ground (no DEM on the build machine — in the app the profile comes from the DEM / LiDAR).
- Section 1 — Southern Türkiye: 26 towers, mean span 400 m, 393.9 t steel, ruling span 375 m, EDS 20 % RTS, sag at max. temperature 13.53 m; checks: Ground and crossing clearance PASS, Maximum working tension PASS, Aeolian vibration (H/w) WARNING, Tower spotting PASS, Uplift PASS
- Section 2 — Bulgaria: 26 towers, mean span 400 m, 387.4 t steel, ruling span 375 m, EDS 20 % RTS, sag at max. temperature 13.53 m; checks: Ground and crossing clearance PASS, Maximum working tension PASS, Aeolian vibration (H/w) WARNING, Tower spotting PASS, Uplift PASS
- Section 3 — Southern Germany (Bavaria): 26 towers, mean span 400 m, 393.9 t steel, ruling span 375 m, EDS 20 % RTS, sag at max. temperature 13.53 m; checks: Ground and crossing clearance PASS, Maximum working tension PASS, Aeolian vibration (H/w) WARNING, Tower spotting PASS, Uplift PASS
Optimum tower spotting Automatic
Candidate stations every 25 m, tower types × body / leg extensions, exact weight / wind spans, clearance per tension section; objective = steel + erection + foundation (region unit rates of the engine).
- Section 1 — Southern Türkiye: simple spotting 26 towers / USD 1,166,555 → optimum 24 towers / USD 1,101,104 (5.61 %)
- Section 2 — Bulgaria: simple spotting 26 towers / USD 2,031,932 → optimum 24 towers / USD 1,916,017 (5.70 %)
- Section 3 — Southern Germany (Bavaria): simple spotting 26 towers / USD 2,066,025 → optimum 24 towers / USD 1,950,110 (5.61 %)
Quantities and cost (screening) Automatic
Section quantities per km × the route length (extrapolation — stated, not a full-length spotting). Per-km line cost: the engine's indicative screening defaults; no crossings counted (no OpenStreetMap).
- Extrapolated for 2,418 km: ≈ 6,288 towers, 94,737 t tower steel, 151,553 m³ foundation concrete, 40,605 t conductor, 21,040 insulator sets
- Indicative line cost of the alternatives (engine per-km defaults): Cheapest USD 2,044 million; Least sensitive USD 2,284 million; Shortest USD 1,969 million
Checks and warnings Automatic
Clearance, maximum working tension, aeolian vibration (H/w, CIGRE TB 273), spotting, uplift — per section.
- Aeolian vibration (H/w): WARNING — 2 section(s) above the CIGRE TB 273 undamped limit 1125 m — specify vibration dampers
Access roads and crossings Runs in the app
Road / rail / river / power-line crossings, access tracks and abnormal-load routes need OpenStreetMap and a routing service — not available on the build machine.
- In WaiMAP: Line routing & mechanics → route → crossings and access estimate; Logistics → abnormal-load check for transformers and tower sections.
Maps, alternatives and figures
Rendered from the engine results; every figure carries the WaiMAP stamp and the attribution of each visible layer.
3D: no 3D render is published for this demonstration; in the app, Project 3D shows towers, PV tables, buildings and point clouds of your own project (Pro and above).
Tables
Route alternatives
| Alternative | Length (km) | × straight line | Settled (km) | Flood-prone (km) | Water (km) | Angle points | Indicative cost (USD million) |
|---|---|---|---|---|---|---|---|
| Cheapest | 2,418 | 1.046 | 34 | 122 | 2 | 60 | 2,044 |
| Least sensitive | 2,703 | 1.169 | 17 | 80 | 6 | 61 | 2,284 |
| Shortest | 2,330 | 1.008 | 108 | 479 | 40 | 3 | 1,969 |
Representative sections — design
| Section | Start (km) | Towers | Mean span (m) | Steel (t) | Concrete (m³) | Conductor (t) | Insulator sets |
|---|---|---|---|---|---|---|---|
| Section 1 — Southern Türkiye | 29.8 | 26 | 400 | 393.9 | 630 | 167.9 | 87 |
| Section 2 — Bulgaria | 1124.6 | 26 | 400 | 387.4 | 620 | 167.9 | 87 |
| Section 3 — Southern Germany (Bavaria) | 2365.4 | 26 | 400 | 393.9 | 630 | 167.9 | 87 |
Sag-tension (section 1, ruling span)
| Case | °C | H initial (kN) | % RTS initial | Sag final (m) | Swing (°) |
|---|---|---|---|---|---|
| Everyday stress (EDS) | 15 | 30.02 | 20.1 | 11.12 | 0 |
| Minimum temperature | -20 | 34.92 | 23.4 | 9.68 | 0 |
| Extreme wind | 10 | 56.09 | 37.7 | 12.42 | 61.8 |
| Ice (radial 6 mm, 900 kg/m³) | -5 | 41.07 | 27.5 | 10.86 | 0 |
| Ice + reduced wind | -5 | 49.4 | 33.1 | 11.37 | 37.9 |
| Maximum operating temperature | 80 | 24.29 | 16.3 | 13.53 | 0 |
Tower spotting — baseline vs optimised (potential savings)
| Section | Region rates | Towers (simple) | Towers (optimum) | Simple (USD) | Optimum (USD) | Saving (USD) | Saving (%) |
|---|---|---|---|---|---|---|---|
| Section 1 — Southern Türkiye | TR | 26 | 24 | 1,166,555 | 1,101,104 | 65,451 | 5.61 |
| Section 2 — Bulgaria | EU | 26 | 24 | 2,031,932 | 1,916,017 | 115,915 | 5.70 |
| Section 3 — Southern Germany (Bavaria) | EU | 26 | 24 | 2,066,025 | 1,950,110 | 115,915 | 5.61 |
| Total of the three sections | 5,264,512 | 4,967,231 | 297,281 | 5.65 |
Potential savings in this demonstration
Potential savings in the three sections: USD 297,281 (5.65 %) — Tower spotting on the three representative 10 km sections (30 km of the 2,418 km route): tower steel, erection and foundations.
Same sections with the angle point moved to mid-section (5.0 km): Section 1 0.00 %; Section 2 0.00 %; Section 3 0.00 %. The saving depends on the geometry — where equal spans already fit, simple spotting is optimal. Method, price date, exclusions and constraints: savings method. Verified savings: no verified project comparison published yet.
Checks, warnings and limitations
- Full-length spotting was not run: three representative 10 km sections were computed and their per-km quantities extrapolated (stated wherever used).
- Level-ground profile in the sections (no DEM on the build machine): real terrain changes spans, extensions and tower counts.
- The cost surface has no slope, protected areas, forests or OpenStreetMap crossings; routes are corridor screening, not alignments.
- Crossing the Turkish Straits region: the cheapest route crosses open water (water km in the table) — a submarine cable or long-span crossing needs its own study.
- Cross-border interconnection needs both TSOs, ENTSO-E planning and permits; none of this is assessed here.
- Unit rates are the engine's indicative 2026 screening defaults (region factors), not quotes.
How a stakeholder uses it
- TSO / grid plannerCompares corridor alternatives and their exposure before the formal planning process
- Developer / investorReads length, indicative cost and the open risks (water crossing, settlement, flood plains)
- EPC bidderUses tower counts, steel and foundation quantities per km for a first bid estimate
- Lender's technical adviserSees methods, assumptions, checks and what is still missing
Time and effort
Engine computation time for the whole story on the build machine: 17.6 s (measured on 2026-10-13 06:00 UTC; Intel(R) Xeon(R) Processor @ 2.10GHz, 2 cores). Data preparation, review and reporting time are not included and are not estimated here.
Downloads
- Sample report (PDF)Drawn by the WaiMAP report engine with the official cover — design status "Concept", approval status "Pre-feasibility only", labelled as a demonstration.
- Calculation summary (CSV)Every key value with its unit, engine and source.
- Demonstration geometry (GeoJSON)Opens read-only on the WaiMAP map: Open in WaiMAP.
Try it on your own project
Open Line routing & mechanicsRun a Site Check along the corridor
Video coming soonReserved for approved real project material related to Whitewell NPP – Bulgaria – Germany transmission corridor (demonstration). No real project material is published here yet; nothing on this page describes a real project.