摘要
台灣地區各公路單位所使用之柔性路面設計方法大都依循美國方法American Association of State Highway and Transportation Officials (AASHTO) 設計法，由於AASHTO設計法是引用美國本土資料而得，同時具有簡便之正面功能，近年來不論在美國或是國際間，鋪面設計法已經由傳統的經驗設計法轉變為力學-經驗設計法(Mechanistic-Empirical Pavement Design Guide，MEPDG)，這種應力設計法是以一種頻率分佈來表示整個軸重變化，可以更深入及精確評估不同荷重對鋪面績效之影響，而不是以傳統18 kip (80kN)的單軸重當量值ESAL來表示。而台灣國道高速公路通車迄今已逾20年，隨著重車流量的不斷增加，與鋪面設計息息相關的交通特性，例如軸次及荷重，也隨著重車流量的成長而有變異，這些變異最後會影響鋪面厚度設計的結果，更需將相關交通特性的變異性逐一探討，回饋至高速公路管理系統以及鋪面設計上。
本文經由收集近年的國道1號岡山地磅、國道3號善化地磅及竹田地磅之重車軸重軸次資料，並使用統計學無母數統計法(Non-Parametric Statistic)來分析軸重分佈的變化性，其結果顯示國道1號岡山南磅及北磅的重車分佈有相當大的不同，岡山北磅以半聯結車車流量最多，單體大貨車次之，岡山南磅則剛好相反，顯見北上路段比南下路段的鋪面要承受更多的重車考驗。另外由收集的資料比較國道3號善化地磅靜態與動態地磅的差異，發現每一輛重車動態和靜態地磅對於重車總重差異量約在 ± 4噸之間，而且呈現類似常態分佈的狀況，以95年而言，單體大貨車U11各月的單軸分佈相似幾乎不受時間的影響，同時單體大貨車U11在善化地磅不論北上或南下不同行車方向的軸重分佈是類似的。不論單軸或雙軸國道3號善化南磅及竹田南磅的U11、U12及S112軸重分佈均無顯著的差異。本文希望經由長期收集及統計方法了解軸重分佈在國道交通特性的變化，並以最經濟及最短的時間建立本土性軸重分佈，以利應力鋪面設計法順利推動。

Abstract
Flexible pavement design methods adopted by Taiwan Department of Highway are mostly in accordance with U.S.A.'s method ,American Association of State Highway and Transportation Officials (AASHTO ) designs method. At the same time, it is a easy and convenient design method. Wherever in U.S.A. or international, the design law of Flexible pavement design methods has been changed from traditional experience law into mechanics - experience one (Mechanistic-Empirical Pavement Design Guide, MEPDG). The new design method is expressed with whole axle load distribution other than single equivalent ESAL of 18 kip (80kN ). During the running of 20 years of Taiwan National Department of Highway ,the related traffic character like axle load frequency and truck weight are getting variable with growth of heavy-truck traffic flow. The variety, finally, will cause to influence of design result of pavement thickness. So, it is needed to analyze the variety of those relevant traffic character and to feedback to the administrative system of highway.

This research collectes important data regarding the axle load of heavy truck from Taiwan National highways No.1 Gangshan weight station and No.3 Shanhua weight station and Jhutian weight station in recent years.It uses statistics (Non-Parametric Statistic ) to analyze the variety of axle load distribution. The result shows that the load distribution of Gangshan south weight station on National highways No.1 is greatly different from that of Gangshan north weight station .The heavy-vehicle flow on north scale is mostly of semi-trailer, and secondly, the single unit truck . However, the Gangshan south weight station gets opposite result. Obviously, the load of north section is heavier than that of south section . It also compares the variety of static weight station with dynamic one of Shanhua weight station. We find the difference of 4 tons for each heavy-vehicle between static and dynamic weight station. And it always appears normal distribution. Besides, the statistically test of its U11 spatial and temporal variations also shows that most of monthly single axle load distribution are not significant differences. The difference between distributions observed at opposite direction at a site are not significant . To promote stress pavement design method smoothly , this text via long-term collection and statistical method can bring some understanding of variety of traffic character and to build up native axle distribution efficiently.

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