不確定性下最適擁擠費決定因素之探討

Abstract

本論文討論於開放單一城市體系中，存在擁擠外部性及都市租金需求不確定情況下，都市規劃者應如何課徵最適擁擠費。最適擁擠費的制訂係使競爭均衡下的都市邊界，縮減至都市規劃者所制訂的效率都市邊界。本論文提供下列兩個政策建議給都市規劃者參考：首先，當都市居民對房屋的需求隨著人口擴張而提升時，若隨機移動的租金超越歷史高點，則都市規劃者應提高最適擁擠費，並將其適用於所有的居民。其次，相較於另一個都市，若某一都市的地主預期都市租金波動程度較大，則會延遲開發土地，因而導致此都市的邊界較小。如此一來，擁擠外部性的負面效果將減少，因而亦應對該都市的居民課徵較低的最適擁擠費。

This thesis investigates how the congestion externality interacting with uncertainty in urban rents affects the determinants of optimal congestion tolls in a monocentric open city. Urban planners will design congestion tolls such that urban growth boundary in a competitive equilibrium will be reduced to the efficient growth boundary desired by urban planners. This thesis derives two main policy implications for urban planners. First, when the demand for housing increases with the expansion of population such that the stochastic urban rents pass their historically high levels, urban planners should then raise the optimal congestion tolls and apply them to all residents. Second, as compared to another city, when a city’s landowner expects the urban rents to be more volatile, the city’s landowner will develop their vacant land at a later date, and thus the urban boundary will be smaller. As a result, the city’s planner should impose lower optimal congestion tolls as a result of a smaller negative effect of congestion externality.