本文推導通勤者在階梯式收費結構下通過瓶頸路段之均衡擁擠(排隊)成本及出發 率。研究結果闡明了通勤者在該收費結構下之出發分散行為模式，也驗證了以前之文獻對於 該收費結構所能產生之擁擠減少效果的預測。因為在均衡狀態下存在一群於收費站前等待收 費降低或結束時方才願意進入該瓶頸路段之通勤者，故為達成預期之擁擠減少效果，必須在 收費站前設置足以容納這些通勤者之等候車道或儲車空間。

　　　　　This paper shows the equilibrium queueing costs and departure rates at a road bottleneck under step toll schemes. The results depict detailed commuter behaviors about departure decentralization due to step toll schemes, also examine the effects of step tolls on queueing reduction conjectured by previous literature. Because there are some waiting commuters who are not willing to enter the bottleneck unitl the toll becomes lower or the toll has completely lifted under the step toll equilibrium, adequate waiting spaces may be required in front of the toll booth to achieve the expected queueing reduction.