Aggregate Travel Demand Analysis: A Cross-National Comparison

傳統運輸需求理論認爲總體旅運需求係受到社經變數的影響。就技術上而言，建構總體旅運需求模式事實上已存在既定的操作程序，但最大的困難點常是在總體資料的可獲性；特別是這些資料多數是由各國政府機構所彙整與發佈，經常無法完全符合研究者所需，使得模式構建工作遭遇到極大的困難。爲此，本研究嘗試以台灣政府所彙整的跨國性運輸資料庫爲基礎，藉由搜尋國外資料來源（如聯合國與歐盟），將該資料庫予以修正與更新，使之成爲一個足以建構總體旅運需求模式的完整資料庫。經修正後的資料庫共計涵蓋了13年(1992-2004)、9個國家（含台灣）的總體資料。接著，本研究以這些資料建構總體旅運需求模式。參數校估結果顯示，國民所得與通訊發展兩個變數是影響總體旅運需求的兩大因素；所得彈性顯示鐵路是傾向於必需品，不容易隨著所得的變動而有太明顯的變化。此外，通訊發展對大眾運輸（鐵路與客運）需求呈現負面影響，卻對私人運具（小汽車）呈現正面影響，顯示通訊科技的進步與普及應用，極可能間接帶動小汽車的成長，卻抑制大眾運輸的需求，此一結果頗值得運輸規劃者深思。

關鍵字

引申需求；總體旅運需求；通訊需求；所得彈性；跨國性資料

並列摘要

In traditional travel demand theory, aggregate travel demand is considered being greatly impacted by socioeconomic variables. Technically, modeling the impacts of these socioeconomic variables on aggregate travel demand is somewhat established practice as long as the data needed are all available. Unfortunately, such data usually come from government and it's affiliated departments and are often insufficient for modeling task. On this account, based on the existent data in Taiwan government departments, this study makes efforts to expand and refine them into a more complete dataset, and then uses such a data set to implement the modeling task. The expanded data set is a chronologically (1992-2004) cross-national (nine nations including Taiwan) one containing primary data needed for modeling travel demands. With these data, then it starts building travel demand models and estimating the corresponding parameters. The estimation results show that the national income and telecommunications development are the two variables having the most significant effects on travel demands. The small positive income elasticity indicates that rail is more like necessity goods. whose demand tends to remain steady irrespective of income effect. Moreover, telecommunications development has negative effect on public 1nodes: rail and air, but has positive effect on the private mode: car. This implies that the telecommunications advancement is possibly to encourage the use of private mode, while discourage that of public mode: a result that transportation planners would least like to see.

並列關鍵字

derived demand ； aggregate travel demand ； telecommunications demand ； income elasticity ； cross-national data

參考文獻

Choo, S.,P.L. Mokhtarian,I. Salomon(2005).Does Telecommuting Reduce Vehicle-miles Traveled? An Aggregate Time Series Analysis for the US.Transportation.32(1),37-64.