There is an increased interest from transit agencies to replace fixed-route transit services with on-demand public transits (ODT). However, it is still unclear when and where such a service is efficient and sustainable. To this end, we provide a comprehensive framework for assessing the sustainability of ODT systems from the perspective of overall efficiency, environmental footprint, and social equity and inclusion. The proposed framework is illustrated by applying it to the Town of Innisfil, Ontario, where an ODT system has been implemented since 2017. It can be concluded that when there is adequate supply and no surge pricing, crowdsourced ODTs are the most cost-effective transit system when the demand is below 3.37 riders/km2/day. With surge pricing applied to crowdsourced ODTs, hybrid systems become the most cost-effective transit solution when demand ranges between 1.18 and 3.37 riders/km2/day. The use of private vehicles is more environmentally sustainable than providing public transit service at all demand levels below 3.37 riders/km2/day. However, the electrification of the public transit fleet along with optimized charging strategies can reduce total yearly GHG emissions by more than 98%. Furthermore, transit systems have similar equity distributions for waiting and in-vehicle travel times.

翻译：交通机构对用需求响应型公共交通（ODT）替代固定线路公交服务的兴趣日益增加。然而，此类服务在何时何地具有高效性和可持续性仍不明确。为此，我们提出一个综合框架，从总体效率、环境足迹、社会公平与包容性三个维度评估ODT系统的可持续性。通过将该框架应用于加拿大安大略省因尼斯菲尔镇（该镇自2017年起实施ODT系统）进行实例验证，结果表明：当供应充足且无动态定价时，众包ODT在需求低于3.37人次/平方公里/日时是最具成本效益的交通系统；当众包ODT采用动态定价且需求介于1.18至3.37人次/平方公里/日之间时，混合系统成为最具成本效益的交通方案。在所有需求低于3.37人次/平方公里/日的水平下，私家车使用比提供公共交通服务更具环境可持续性。然而，通过优化充电策略实现公共交通车队电气化，可使全年温室气体总排放量减少超过98%。此外，各交通系统在候车与乘车时间的公平性分布方面具有相似特征。