測量リスクシミュレーター：測地系・座標誤差による経済的影響試算
測地系ペア、測線長、標高、精度等級を選択することで、水平位置ズレ、グリッド投影歪み、および想定される是正・手戻り費用のリスク階層を即座にシミュレーションします。
| 公的機関・基準規格 | 要求許容誤差 | 発生誤差 | 判定結果 |
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測量リスク：技術FAQ
How large is the WGS84 to NAD83 coordinate shift?
The WGS84 and NAD83 reference frames differ by less than 2 meters across CONUS. However, the specific realization epoch matters: NAD83(2011) epoch 2010.0 vs. a dynamic WGS84 GNSS output can differ by up to 1.5m in some areas due to tectonic motion and reference frame definitions.
What is the forensic threshold for a construction survey error?
For boundary surveys, the standard of care is typically 1:10,000 linear precision. A 100mm (10cm) error on a 1,000m survey baseline is 1:10,000, the absolute minimum. Combined scale factor errors routinely exceed this when surveyors ignore the grid-to-ground conversion, creating defensible grounds for negligence claims.
How does datum shift translate to legal liability?
Courts have consistently held that licensed land surveyors and civil engineers are liable for positional errors that exceed the surveying standard of care. A datum shift greater than the tolerable positional uncertainty for the accuracy class, whether from using the wrong datum, wrong epoch, or ignoring combined scale factors, is sufficient to establish breach of professional duty.
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