On-demand ridesourcing services from transportation network companies (TNCs), such as Uber and Lyft, have reshaped urban travel and changed externality costs from vehicle emissions, congestion, crashes, and noise. To quantify these changes, we simulate replacing private vehicle travel with TNCs in six U.S. cities. On average, we find a 50–60% decline in air pollutant emission externalities from NOx, PM_2.5, and VOCs due to avoided “cold starts” and relatively newer, lower-emitting TNC vehicles. However, increased vehicle travel from deadheading creates a ∼20% increase in fuel consumption and associated greenhouse gas emissions and a ∼60% increase in external costs from congestion, crashes, and noise. Overall, shifting private travel to TNCs increases external costs by 30–35% (adding 32–37 ¢ of external costs per trip, on average). This change in externalities increases threefold when TNCs displace transit or active transport, drops by 16–17% when TNC vehicles are zero-emission electric, and potentially results in reduced externalities when TNC rides are pooled.

中文翻译：

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空气污染、温室气体和交通外部性将私家车出行转移到乘车服务的收益和成本

Uber 和 Lyft 等交通网络公司 (TNC) 的按需乘车服务已经重塑了城市出行，并改变了车辆排放、拥堵、碰撞和噪音等外部成本。为了量化这些变化，我们模拟了在美国六个城市用跨国公司取代私家车出行。平均而言，我们发现 NO x、PM _{2.5 的}空气污染物排放外部性下降了 50-60%，以及由于避免“冷启动”和相对较新、排放量较低的 TNC 车辆而产生的 VOC。然而，由于无头行驶而增加的车辆行驶会导致燃料消耗和相关温室气体排放量增加约 20%，以及因拥堵、碰撞和噪音导致的外部成本增加约 60%。总体而言，将私人旅行转移到跨国公司会使外部成本增加 30-35%（平均每次旅行增加 32-37 美分的外部成本）。当跨国公司取代公共交通或主动运输时，这种外部性变化会增加三倍，当跨国公司车辆是零排放电动汽车时，这种变化会下降 16-17%，并且当跨国公司拼车时，可能会导致外部性减少。