We analyze the effect of the US transportation system on economic activity by building a quantitative dynamic general equilibrium model with a taxpayer-funded transportation capital stock. We highlight stark differences between the positive welfare effects of additional infrastructure spending in the long run, and its potentially negative effects when we account for the large transition (time and delay) costs to build. We also quantify large differences between the effects of additional infrastructure spending and efficient transportation policies, such as congestion pricing and eliminating laws that artificially inflate input prices, concluding that taxpayer-funded transportation improvements that increase GDP significantly may produce smaller welfare gains than efficient policies that increase GDP modestly.

我们通过使用纳税人资助的运输资本存量建立定量动态一般均衡模型来分析美国运输系统对经济活动的影响。我们强调从长远来看，额外基础设施支出的积极福利效应与其在考虑到建设的巨大过渡（时间和延迟）成本时的潜在负面影响之间存在明显差异。我们还量化了额外基础设施支出和有效交通政策（例如拥堵收费和取消人为抬高投入价格的法律）之间的巨大差异，得出的结论是，纳税人资助的显着增加 GDP 的交通改善可能比有效的政策产生更少的福利收益GDP小幅增长。