The growth of e-commerce has bridged the gap between the consumer and the retailer, bringing prosperity for both. However, in a quest to achieve even larger profits and market share, e-retailers compete to offer consumers cheaper shipping, expedited deliveries, free returns, and other lucrative deals. To keep pace with these growing needs of e-commerce, e-retailers have piloted various alternative distribution strategies. To aid a fuller understanding of the costs and benefits of these distribution strategies in diverse delivery environments, this work develops a multi-echelon last-mile distribution model using Continuous Approximation (CA) techniques. The model results suggest that traditional last-mile delivery with diesel trucks is a good fit for e-retailers delivering in dense environments with lenient temporal constraints (parcel service), a strategy that allows for demand consolidation and thus low-cost low-emission distribution. For e-retailers delivering in sparsely populated environments with stringent temporal constraints (grocery delivery), this work finds outsourcing alternatives (crowdsourced delivery, customer self-collection) to render low-cost distribution albeit with high emissions. As a result, the authors suggest the use of low-volume low-pollution vehicles from smaller consolidation facilities close to the market to provide expedited deliveries at fairly low costs and emissions. The analysis bolsters the case for the use of electric trucks for last-mile deliveries, as the study finds an electric truck fleet to not only eliminate tailpipe emissions but also to lower distribution costs compared to a diesel truck fleet. Thus, with this work the authors discuss the opportunities and challenges associated with different last-mile strategies for e-commerce delivery.

电子商务的发展弥合了消费者和零售商之间的鸿沟，为双方带来了繁荣。然而，为了获得更大的利润和市场份额，电子零售商竞相为消费者提供更便宜的运输、更快的交付、免费退货和其他有利可图的交易。为了跟上电子商务不断增长的需求，电子零售商试行了各种替代分销策略。为了帮助更全面地了解这些分销策略在不同交付环境中的成本和收益，这项工作使用连续近似 (CA) 技术开发了一个多级最后一英里分销模型。模型结果表明，使用柴油卡车的传统最后一英里交付非常适合在时间限制宽松的密集环境中交付的电子零售商（包裹服务），一种允许需求整合并因此实现低成本低排放分配的策略。对于在人口稀少的环境中提供严格的时间限制（杂货配送）的电子零售商，这项工作找到了外包替代方案（众包配送、客户自提），以实现低成本配送，尽管排放量很高。因此，作者建议使用来自靠近市场的小型整合设施的低容量低污染车辆，以相当低的成本和排放提供快速交付。该分析支持使用电动卡车进行最后一英里交付的理由，因为该研究发现，与柴油卡车车队相比，电动卡车车队不仅可以消除尾气排放，而且还可以降低配送成本。因此，