蓋設超高壓輸電線（high voltage overhead transmission line，簡稱HVOTL）可能產生巨大的外部成本。本文以台灣電力股份有限公司（簡稱台電）「南投–彰林」線路為例，應用條件評估法（contingent valuation method，簡稱CVM）所設計的問卷調查資料，建立以農地價格為自變數的計量模型，採用2SLS和Heckit等方法來估計該線路對農地價值所產生的外部成本。結果顯示：距離HVOTL愈近的農地，願付價格愈低。另外，該線路全長23.6公里、兩旁600公尺內農地價值的損失高達171億元；相較於台電建造此條線路所花費的27億元，高出6倍以上。本研究結果應可提供台電設置超高壓輸電線甚至政府從事國家建設開發案時之參考。

Building high voltage overhead transmission lines (HVOTL)may incur huge external social cost. This study attempts to estimate such external cost using the Taipower Company's Nantou-Changlin HVOTL as a case study. This HVOTL likely affects the values of farmland. Data were collected from a field survey designed from the contingent valuation method (CVM). An econometric model using farmland price as the dependent variable was specified and estimated by two-stage least squares (2SLS) and Heckman two-step model (Heckit). The econometric results show that building this HVOTL would reduce the value of farmland within 600 meters from this line with 23.6 km on both sides. The closer to HVOTL, the lower is the farmland price. The total lost farmland value amounts to 17.1 billion NT dollars. This amount is more than six times the construction cost of 2.7 billion. These research results should be very useful to the Taipower Company and government agencies in assessing the external social cost of the construction of HVOTLs in Taiwan.