اقتصاد سیاسی و انتخاب سیستم حمل و نقل شهری

This paper analyzes the political economy of transport-system choice, with the goal of gaining an understanding of the forces involved in this important urban public policy decision. Transport systems pose a continuous trade-off between time and money cost, so that a city can choose a fast system with a high money cost per mile or a slower, cheaper system. The paper compares the socially optimal transport system to the one chosen under the voting process, focusing on both homogeneous and heterogeneous cities, while considering different landownership arrangements. The analysis identifies a bias toward underinvestment in transport quality in heterogeneous cities.

A frequently heard criticism of local public policy in the US concerns the choice of transport systems. In particular, environmentalists and other activist groups often argue that US cities have overinvested in automobile-oriented transportation infrastructure at the expense of public transit. They argue that urban residents would be better off if past transport investment had favored rail and bus systems, with less money spent on freeways. This argument has gained force recently with the emergence of urban sprawl as a policy issue. Critics argue that freeway investment has encouraged excessive spatial growth of US cities.1 Unfortunately, urban public economics provides almost no insight into the issues surrounding the choice of an urban transport system. Transport costs are viewed as exogenous in the typical urban model rather than being the result of a prior policy decision regarding the nature of the transport system. As a result, the above criticism of transport investment patterns is difficult to evaluate using existing models. To remedy this deficiency, the present paper proposes and analyzes a model where the transport system is chosen endogenously, with the choice carried out in the context of a simple urban general equilibrium framework. The goal of the analysis is to compare the socially optimal transport system to the one selected under the public-choice process.

This paper has analyzed the political economy of transport-system choice, with the goal of gaining an understanding of the forces involved in this important urban public policy decision. The analysis shows that, when the city is homogeneous, the chosen transport system is socially optimal regardless of landownership arrangements. This equivalence disappears, however, in a skill-heterogeneous city, with the chosen transport system being less expensive and slower than the optimal system under realistic skill distributions. This underinvestment, which is more pronounced under resident landownership, contradicts the allegations of critics who argue that the US has invested too much in fast, expensive freeways and too little in public transit. However, the model omits transport subsidies, which encourage investment in expensive systems, and adding this institutional feature could reverse the tendency toward transport underinvestment. Indeed, one implication of the analysis is that, because of this stimulative effect, such subsidies may be warranted. Since the models analyzed in the paper are highly stylized, the conclusions reached are at best suggestive. However, the analysis provides a starting point for more realistic treatments of the transport-choice problem. One improvement would be to generate suburban location of high-skill consumers through endogenous land consumption rather than a taste for location, as is done in the present analysis. While the paper's continuum model becomes intractable under this modification, Brueckner (in press) is able to analyze a model with two income groups under the assumption of Leontief preferences. Further work in this direction (perhaps numerical in nature) would be useful. Another improvement would involve relaxation of the model's fixed-leisure assumption, allowing time costs to be generated as a byproduct of an endogenous labor–leisure choice. It can be shown that, when consumers have Cobb–Douglas preferences over consumption and leisure, some of the initial steps of the analysis are unaffected, but none of the major results can be derived.18