Check compensation for using underground space
An underground railway tunnel or water or sewer facility may use a defined volume under an easement while the owner retains the land.
Compensation concerns lost use value rather than acquisition of the entire parcel.
Keep this separate from land expropriation compensation.
This calculator separates Korean railway construction, water supply and public sewerage rules.
It compares a scenario range with the combined rate implied by notified base compensation.
Differences identify evidence to request; they do not determine an appraisal error or an entitlement to more money.
Urban rail requires the applicable city or province ordinance and is excluded.
A GTX route name alone does not determine the governing statute.
Check the project designation and notice.
Power lines, gas pipes, communication ducts and special mineral-water compensation are outside scope.
Read unit price, registered area and depth consistently
Enter the KRW/m² price from the notification or appraisal.
The calculator does not estimate an appraisal from an official land price or nearby sales.
If only a total is known, request the unit price and area first.
Both must be positive.
Use the easement’s registered area rather than the entire parcel area.
Railway rules normally add a 0.5m margin on each side of the facility width, but parallel tunnels and other cases may require a different scope.
This tool uses the confirmed area instead of determining it from width and length.
Cover is measured from the facility crown to ground.
Water and sewer compensation depth starts at the top of the upper protection layer.
The normal protection layer is 3m above and below a facility up to 3m high, otherwise 4m.
Operators may determine exceptions for shallow or unusual facilities.
Enter the confirmed compensation depth.
Land-use bands reflect actual use and best use, not merely a cadastral label.
Railway high-rise and water high-rise classifications differ.
Use the band in the relevant appraisal.
Rail impairment and existing-building age
Rail base compensation = appraised unit price × easement area × spatial impairment rate.
The impairment rate adds building, underground and other-use losses.
Building loss = α × lost-floor utility sum / best-use floor utility sum.
Underground loss = β × depth efficiency P.
Standard rail α/β/γ are 0.80/0.15/0.05 for high-rise, 0.75/0.10/0.15 for mid- and low-rise, 0.70/0.15/0.15 for housing and 0.80/0.10/0.10 for farmland/woodland.
Other-use loss applies the underground allocation.
For tunnels with cover up to 20m, the annex’s highest above/below allocation ratio is used; other cases show the table allocation range.
For an existing building at or near best use, impairment = (vacant-land building loss + underground loss) × aging ratio + other-use loss.
Aging ratio = effective age / economic useful life.
This tool treats a ratio above one as fully aged and caps it at one.
Use appraised effective age and useful life, including maintenance and renovation, rather than simply subtracting completion dates.
Rail compensation is a lump sum.
The water/sewer optional minimum and agreement incentives below are not added to railway compensation.
Buildable floors and floor-utility intervals
For a weathered-rock PD-3 rail tunnel with 20m cover, the reference is 21 above-ground floors and two basement floors.
Weathered soil, soft rock, hard rock and cut-and-cover use different tables.
Between listed depths, the two reference endpoints form a range.
Unlisted depths are not extrapolated.
These are appraisal references, not construction permission or an excavation safety finding.
Water/sewer cover references of 5/10/15/20/25/30/35m or more correspond to 7/12/16/19/22/25/28 above-ground floors.
The permitted two-floor construction/geology adjustment is included.
Below 5m, appraised buildable-floor bounds or an appraised utility ratio are required.
Water/sewer floor weights have lower and upper values.
The ratio lower bound uses lost-low / (lost-low + retained-high); the upper uses lost-high / (lost-high + retained-low).
This preserves the shared lost-floor term in the numerator and denominator.
Rail low-rise, farmland/woodland and unlisted floor/use combinations require the appraisal’s lost-floor utility / total utility (%).
Entering this ratio overrides automatic utility weights.
Appraised buildable-floor endpoints must be entered together with lower no greater than upper.
Additional water and sewer adjustments
Water/sewer base compensation = unit price × area × (spatial impairment + additional adjustment).
The adjustment adds facility, parcel and registration factors.
External heights up to 2.5m use 0.00–0.20 times underground loss; over 2.5m through 5m use 0.20–0.40; over 5m use 0.40–0.60.
Base parcel-factor intervals are 0.30–0.60 for developed land, 0.20–0.40 for farmland and 0.10–0.30 for forest.
Center passage or an easement share over 30% gives high grade.
Otherwise a corner or share up to 10% gives low grade; remaining cases are middle.
This tool maps grades to the interval’s upper, midpoint or lower value as a scenario, not a legally fixed grade rate.
Optional sensitivity includes ±0.10 for the parcel factor and ±0.05 for α/β/γ while keeping their sum equal to one.
Registration securing the right adds 3%.
Independently minimized or maximized component rows may not sum to the combined endpoints.
For developed land with cover up to 2m, surface loss is at least 0.20.
Farmland/forest surface loss applies only up to 2m cover and ranges from 0.10 to 0.15; beyond 2m it is zero.
Confirm the operator’s special protection-layer decision for shallow facilities first.
Limiting depth and the deep-space branch
Rail uses cover depth; water/sewer use compensation depth.
Swapping these measurements can change the branch.
Compensation does not automatically become zero beyond the limiting depth.
Rail depth beyond the limit up to 20m gives 0.5–1.0%; over 20m through 40m gives 0.2–0.5%; over 40m gives 0–0.2%.
High-rise rail cover of 60m exceeds the 40m limit by 20m.
Do not confuse total cover with excess depth.
At the exact rail limiting depth, the published endpoints require review rather than an automatic result.
Water/sewer compensation depth exceeding the limit uses impairment of 0–2%, with only registration added.
Registered cases therefore show a combined 3–5%, unregistered cases 0–2%.
Do not add the ordinary facility or parcel adjustment again.
Special mineral-water use may require separate compensation.
Limiting depth by scheme and appraised land-use band| Scheme | Band | Limit (m) |
|---|
| Rail | High / mid / low / housing / farm-woodland | 40 / 35 / 30 / 30 / 20 |
| Water / sewer | High / mid / low / farmland / forest | 50 / 45 / 40 / 30 / 25 |
Optional minimum compensation and agreement incentives
If water/sewer compensation is below KRW700,000 per parcel, the operator may pay a minimum up to KRW700,000, limited to 50% of price × area.
It is applied only when the operator-confirmation checkbox is selected.
This provision does not reduce an original award already above KRW700,000 to 50%.
The operator may pay an additional 7% of base compensation for agreements through day 60, or 5% on days 61–90 after notification.
The optional KRW100,000 incentive minimum applies only to the first, 60-day tier and cannot exceed 50% of base compensation.
It does not apply to a day-61 agreement.
For KRW700,000 base compensation, 7% is KRW49,000; the optional minimum increases this to KRW100,000 through day 60.
On day 61, the 5% amount is KRW35,000.
A KRW100,000 base limits the early minimum to KRW50,000.
Confirm actual operator payment practice.
The compensation minimum is per parcel; the incentive minimum is per owner.
This tool assumes one owner and one parcel.
Do not calculate multiple parcels separately and add an owner-level minimum repeatedly.
Separate any incentive already included in a notification before comparing the base amount.
Use the calculator step by step
First confirm the project statute and choose rail, water or sewer.
Second enter the appraised price and easement area, then reconcile average depths, land-use band and facility dimensions with the drawings.
Third enter best-use floors and any required appraisal utility or aging overrides.
Fourth, for water/sewer, confirm whether the operator applies the optional minimum and incentive, then enter both notification and planned agreement dates.
Fifth compare the result and implied notified rate, and request reasons for any differing inputs.
Being inside the range does not confirm correctness; being outside does not guarantee an increase.
Dates are nominal calendar references excluding the notification day.
A 2026-11-01 notice gives 2026-12-31 for day 60 and 2027-01-30 for day 90.
Confirm effective notification, first-day exceptions, endpoint holidays and operator opening hours.
Holiday extensions are not determined here.
Later-year dates assume unchanged 2026 rules.
A fictional railway example
Assume high-rise land, a weathered-rock tunnel, 20m cover, best use of 20 floors, KRW1,000,000/m² and 100m².
The reference allows 21 above-ground floors, so building loss is zero.
Underground loss is 0.15 × 0.500 = 0.075; other-use loss is 0.05 / 3.
The combined rate is approximately 9.166667%.
Applied to a KRW100,000,000 reference value, compensation is KRW9,166,666–9,166,667.
Internal decimals are retained; the lower endpoint is rounded down and the upper up to whole KRW.
This is a display policy, not the operator’s payment-rounding rule.
A notified base amount of KRW9,200,000 implies 9.2%.
It is slightly above the fictional standard range, so first check included items, allocation adjustments, price, area and rounding.
The difference between underground-use compensation and a sale price is not an investment profit measure.
Evidence to collect before agreement
Request the appraisal’s band, best-use and buildable floors, floor utility, P or E depth bracket and adjustment reasons.
Reconcile the registered easement area with drawings showing the protection layer, cover and compensation depth.
For existing buildings, obtain effective-age and useful-life evidence, not just a completion year.
Near the planned agreement date, confirm notification evidence, the operator’s actual closing date, whether incentives are paid and how amounts are aggregated per owner.
Buyers should obtain design and geotechnical advice before using reference floors in a development plan.
The selected scenario range does not cover every appraisal discretion or establish legal minimum/maximum awards.
Taxes, litigation costs, residual-parcel loss, construction damage and special groundwater compensation are not included.
Recheck effective dates and transitional provisions after amendments.
Frequently asked questions
Can I use this for a subway?
Urban rail is excluded because city/province ordinance coefficients must be verified.
Check the project’s statute rather than the line name.
Can I enter the official published land price?
The tool assumes the notified or appraised unit price.
A published price alone is not the actual compensation price; request the appraisal basis.
Which depth do I enter?
Rail uses cover.
Water/sewer require both cover and compensation depth.
Their limiting-depth branch uses compensation depth excluding the upper protection layer.
Does the 3% registration adjustment disappear beyond the limit?
Water/sewer retain only the 3% registration factor in addition to impairment up to 2%, if registered.
Unregistered cases have no registration addition.
Rail does not use this 3% factor.
Is the minimum incentive KRW100,000 on day 61?
No.
The minimum refers only to the 7% tier through day 60.
Days 61–90 use 5% of base compensation, subject to actual discretionary payment.
What if the depth or floors are not listed?
The tool does not extrapolate.
Enter confirmed appraised buildable-floor endpoints or lost-floor utility / total utility to calculate with that evidence.
Is agreement safe if the notice is within the range?
It only means the amount is numerically consistent with selected assumptions.
Review the easement scope, restrictions, adjustments and optional payment conditions before deciding.
Can I aggregate multiple owners or parcels?
The tool assumes one owner and one parcel.
Minimum incentives are owner-level; ask the operator how to aggregate rather than adding separate calculator minima.
Official sources and rule dates
Korea-based 2026 rules checked through the National Law Information OPEN API on 2026-11-09. Rail Act Article 12-2 (MST286613, effective 2026-06-02), Decree Article 14-2 and Annex 1 (MST262339, effective 2024-05-17); Water Decree Article 61-2 and Annex 3-3 (MST286843, 2026-06-09); Sewer Decree Article 6-2 and Annex 1 (MST286151, 2026-06-03).
Recheck amendments, the applicable project statute, actual appraisal adjustments, registered scope, effective notification, owner-level aggregation and operator payment conditions. Ranges do not replace a final appraisal or legal determination.
Turn differences into a document request
Compare the appraisal’s depths, floors, utility weights and area against your inputs, then request the operator’s written calculation basis. Confirm the actual agreement schedule before relying on an optional incentive.