高速公路植栽風險之研究：以國道三號汐止至木柵休息站為例

Abstract

近年來氣候變遷為人類社會及生態系統帶來顯著負面影響，並增加極端氣候事件發生之機率，台灣每年平均會受到三到四次颱風侵襲，當高速公路兩側綠廊樹木若受到颱風影響而倒伏，將導致高速公路之交通堵塞並增加疏通成本，且可能傷及用路人之生命財產安全。故本研究以國道3號里程9k+000~24K+000 (汐止至木柵休息站)、國道三號甲線之路廊範圍為研究基地，為維護高速公路轄區內綠廊之植栽健康，預防樹木倒伏對道路造成安全上之負面影響，本研究建置植栽管理分類體系，利用植栽單元 (plant unit) 和立地單元 (site unit) 疊圖共生成812個管理單元 (management unit)，以瞭解植栽現況。而為瞭解轄區內之植栽風險，故針對管理單元林分進行植栽風險評估，使用IPCC 災害風險評估定義，以管理單元為最小單元，進行植栽風險評估，本研究分析之植栽風險因子包含：坡度、坡向 (衝風地帶)、道路型式、適合植生類型與實際植生類型之比較、倒木危害安全可能性、潛在樹倒區域等6項，並製作植栽風險地圖，評估結果得知轄區內管理單元之風險分級主要以低風險 (占總數約89.78%)、中風險級 (占總數約10.22%) 為主。

Climate change has heightened the frequency of extreme weather, including typhoons that Taiwan faces annually, averaging three to four times. The toppling of trees along freeway green corridors by such typhoons not only disrupts traffic and elevates road clearance costs but also poses risks to motorist’s safety and property. Therefore, this study focuses on a section of National Freeway No. 3, from the 9km to the 24km marker (from Xizhi to the Muzha rest area), and the corridor of National Freeway No. 3A, aiming to maintain the health of the roadside plantations within the freeway jurisdiction to prevent the unsafe conditions caused by poorly growing or unexpectedly fallen trees. By overlaying plantation units and site units, a plantation management system was established, generating a total of 812 management units. To understand the vegetation risk within the jurisdiction, this study explores stand risk assessment for the management units using the IPCC’s disaster risk assessment framework. The smallest units used for the vegetation risk assessments are the management units themselves. The analyzed vegetation risk factors include slope, slope direction (windward zones), road type, comparison of suitable vegetation types with actual vegetation types, potential safety hazards from fallen trees, and potential tree fall areas. These six factors are incorporated into a vegetation risk map. The assessment results indicate that the risk levels within the management units in the jurisdiction are predominantly low risk (approximately 89.78%) and medium risk (approximately 10.22%).