Studies in several cities indicate that ridesourcing (ride-hailing) may increase traffic and congestion, given the substitution of more sustainable modes and the addition of empty kilometers. On the other hand, there is little evidence if smartphone apps that target shared rides have any influence on reducing traffic levels. We study the effects of a shared-mobility service offered by a start-up in Mexico City, Jetty, which is used by travelers to book a shared ride in a car, van or bus. A large-scale user survey was conducted to study trip characteristics, reasons for using the platform and the general travel choices of Jetty users. We calculate travel distance per trip leg, for the current choices and for the modes that riders would have chosen if the platform was not available. We find that the effect of the platform on vehicle kilometers traveled (VKT) depends on the rate of empty kilometers introduced by the fleet of vehicles, the substitution of public versus private transport modes, the occupancy rate of Jetty vehicles and assumptions on the occupancy rate of substituted modes. Following a sensitivity analysis approach for variables with unavailable data, we estimate that shared rides in cars increase VKT (in the range of 7 to 10 km/passenger), shared vans are able to decrease VKT (around −0.2 to −1.1 km/passenger), whereas buses are estimated to increase VKT (0.4 to 1.1 km/passenger), in our preferred scenarios. These results stem from the tradeoff between the effects of the occupancy rates per vehicle (larger vehicles are shared by more people) and the attractiveness of the service for car users (shared vans attract more car drivers than buses booked through Jetty). Our findings point to the relevance of shared rides in bigger vehicles such as vans as competitors to low occupancy car services for the future of mobility in cities, and to the improvement of public transportation services through the inclusion of quality attributes as provided by new shared-mobility services.

在多个城市的研究表明，由于替代了更多可持续的交通方式并增加了空公里，因此骑乘（打车）可能会增加交通和拥堵。另一方面，几乎没有证据表明针对共享乘车的智能手机应用程序对降低交通流量水平有任何影响。我们研究了墨西哥城Jetty一家初创公司提供的共享出行服务的效果，旅行者使用该服务预订了汽车，面包车或公共汽车的共享出行。进行了大规模的用户调查，以研究出行特征，使用该平台的原因以及码头用户的一般出行选择。对于当前选择以及如果平台不可用，骑乘者会选择的模式，我们将计算每个行程腿的行驶距离。我们发现平台对行进的车辆公里数（VKT）的影响取决于车辆车队引入的空公里率，公共与私人运输模式的替代，码头车辆的占用率以及对占用率的假设替代模式。对数据不可用的变量采用敏感性分析方法后，我们估计共享的乘车行程会增加VKT（在7至10公里/乘客的范围内），共享的面包车能够降低VKT（在-0.2至-1.1公里/乘客左右） ），而在我们的首选方案中，公交车估计会增加VKT（每位乘客0.4至1.1公里）。这些结果源于每辆车的占用率（更大的车辆由更多的人共享）和服务对汽车使用者的吸引力（共享的货车比通过Jetty预订的公共汽车吸引更多的汽车驾驶员）之间的权衡取舍。我们的研究结果表明，较大型车辆（例如，作为竞争者的面包车）的共享乘车与低占用汽车服务对未来城市出行的相关性，以及通过纳入新共享服务所提供的质量属性来改善公共交通服务，移动服务。