有害廢棄物替代清運路線優選

Abstract

由於有害廢棄物具有毒性，清運時一旦外洩將對周遭民眾及環境造成危害，故有必要評估清運沿線所影響人口，唯過去研究所建議的二個方法均有誤差，故本研究將建立二個新方法改善之。有害廢棄物清運路徑優選過去的研究大多著重於選擇最短路徑或是單一最適路徑，但如此作除了會加重同一路線區民的風險，亦缺乏應變的替代路線，本研究因而試著建立適當的方法優選替代路徑，預期研究成果可改善優選有害廢棄物清運替代路徑。 有害廢棄物清運沿線所影響人口過去研究是以道路為中心線在影響緩衝距離下之圓形或矩形方法估算，但都會有重複計算或遺漏區域情形，故本研究提出的平行線交會(Line cross zone)及角平分線(Angle bisector)二種新方法來改善影響人口估算誤差，根據案例研究結果，本研究所提出之平行線交會法，改善了重複計算人口之問題，讓人口估算之偏差平均只有0.24%，比過去提出的人口估算方法有更高的準確度。 為了改善以往有害廢棄物清運優選大多只著重單一路徑之問題，本研究因而建立MGA規劃模式依據影響人口、運輸風險、成本及有害物質風險等因子優選替代路徑，亦採用K-Shortest Path (KSP)演算法建立一優選替代路徑之工具，此演算法可找出與最短路徑相近的多個替代路徑，兩工具皆可選出替代路徑，唯KSP工具執行的時間過長，且不易進行多因子分析；以MGA模式進行不同及多因子分析，優選出不同替代路徑組合，且在綜合評估中以指標進一步評選替代路徑組合，分析所選的組合其分散風險的程度，依案例結果，MGA工具可迅速優選出多組具有分散風險能力之替代路徑組合。

Since hazardous wastes (HWs) are toxic, any leak during collection may harm surrounding people and environment. Evaluating the potential risk on residents along HW collection routes is thus desired. Two previously suggested methods for estimating exposed population may have significant errors. Therefore, this study develops two new approaches for improving the estimation. Furthermore, most related studies focused on the shortest route or single optimal route for routing HW transportation. However, a single route not only increases the potential risk posed on the same route, but also lacks alternative routes for diverting the risk. This study was thus initiated to establish appropriate tools for finding appropriate alternative routes. HW transportation may potentially affect population along the collection route. Two previous methods estimated the exposed population based on a circular and rectangular expansion from the road centerline by a pre-specified buffer distance. However, both methods may have duplicate counting or omission problems. Therefore, this study proposes the line-cross-zone and angle-bisector methods to improve the estimation of affected population. According to the results of several case studies, the line-cross-zone method does effectively improve the estimation, with average deviation of 0.24 %, significantly better than those for two previous methods. In addition to the affected population, other factors such as transportation risk, cost, and hazardous material potency are also considered for determining appropriate HW transportation routes. To improve the HW transportation routing, this study develops an MGA-based model for finding alternative routes based on aforementioned factors. The original MGA model is to find good solutions that are maximally different from the optimal one. The MGA-based model is intended to find good alternative routes that can divert the transportation risk. A computer program implementing the K-shortest path algorithm is also developed for finding alternative routes that are close to the shortest one. The MGA-based model and the K-shortest path program both can generate alternative routes. However, the latter took too long to find alternative routes and is difficult to perform multi-factor analyses. Several sets of alternative routes were generated by applying the MGA-based model based different single-factor and multi-factor analyses. Comprehensive evaluation of the sets were implemented and compared based on how well they can divert the transportation risk. The established MGA-based model can quickly generate alternative routes that effectively divert the transportation risk.