Related to the increased encouragement of public transport (PT) by policy-makers, over-crowding in PT has become a major issue worldwide. Whilst the impact of in-vehicle crowding on individuals' travel costs has been considered, we focus on aggregate welfare losses. We apply a Pigouvian framework to the case of subways and compute the economic cost of congestion ($ECC$). We combine data of the 14 metro services of the Paris network with survey data from a contingent valuation study of in-vehicle congestion. The gap between current and optimal PT patronage is 9%, and $ECC$ is moderate. For the entire Paris subway network our benchmark estimate of 64.6 million euros per year amounts to 0.9% of total users' costs. We also propose marginal congestion costs relevant for socioeconomic appraisals of transport projects.

与决策者对公共交通（PT）的更多鼓励相关，PT的过度拥挤已成为世界范围内的主要问题。在考虑了汽车拥挤对个人旅行成本的影响后，我们将重点放在总的福利损失上。我们将Pigouvian框架应用于地铁案例，并计算拥堵的经济成本（$ËCC$）。我们将巴黎网络的14条地铁服务的数据与来自车辆拥堵的或有估值研究的调查数据相结合。当前和最佳PT赞助之间的差距为9％，并且$ËCC$适中。对于整个巴黎地铁网络，我们每年的基准估算为6,460万欧元，占总用户成本的0.9％。我们还提出了与交通项目的社会经济评估相关的边际拥堵成本。