## 4 Current Issues of Last Mile Logistics
### Environmentally Sustainable LML
\begin{table}
\begin{tabular}{p{142.3 pt} p{142.3 pt}} \hline \hline
**LML-Related Issue** & **Research Finding** & **Reference** \\ \hline Multi-criteria decision making for sustainable LML & Conceptual framework to evaluate LML from economic, social, and environmental aspects Bi-criteria auction process of last mile delivery orders that maximizes both economic and environmental sustainability & [73] \\  & A distributed network based on crowd logistics as the most sustainable LML strategy & [74] \\ \hline Environmental impact assessment and sustainable strategies for e-commerce LML & Lower carbon footprints in last mile deliveries through e-commerce than conventional brick-and-mortar stores. Effective reduction in greenhouse gas emissions through local collection and delivery points for failed home deliveries & [43] \\  & Stochastic last mile model to calculate probabilistic estimates of traveling distances and break-even point at which last mile delivery causes less carbon emissions than customer pickup Reduction in light goods vehicle traffic and associated environmental impacts through LML A framework to reduce CO2 emissions in e-commerce LML Principles for sustainable LML & [75] \\ \hline  & Reduction in carbon emissions and delivery distances through a social network enabled package pickup Importance of local authorities to promote cargo cycles Reduction in CO2 emissions per person through shared mobility Emissions and cost savings by using a social network in LML for retail store order pickups & [61] \\ Integration of environmental sustainability into new LML approaches & Slightly more emissions in minimizing operating costs for the last mile delivery system Negative impact of crowdsourcing in LML on the environment of the road Crowd logistics that can be environmentally-friendly only if it is optimized for existing delivery trips & [62] \\  & Both environmental and economic benefits obtained by crowd-shipping through public transportation in urban areas & [63] \\ \hline \hline \end{tabular}
\end{table} 
Table 5: LML-related issues and research findings: Environmental impact. examined LML for light goods from e-commerce retailers in London, and they concluded that last mile deliveries for e-commerce can reduce light-goods vehicle traffic and associated environmental impacts. Ref. [78] developed a framework to reduce carbon dioxide (CO\({}_{2}\)) emissions in e-commerce LML and suggested potential solutions (e.g., re-allocation of vehicles, use of electric vehicles (EVs), reduction in delivery failures, proper vehicle planning, alternative fuels, and urban consolidation centers) to reduce CO\({}_{2}\) emissions in LML. Ref. [79] examined the urban delivery performance of LML for business-to-consumer and business-to-business cases in the United Kingdom. Recent studies have paid more attention to environmental sustainability of new LML operations and approaches that are expected to provide both economic and environmental benefits in urban logistics. Ref. [61] compared last mile delivery distances and greenhouse gas emissions in last mile delivery systems (i.e., door-to-door delivery, designated package pickup, and socially networked package pickup) for online purchases, which were modeled through a genetic algorithm. Their results showed that a social-network-enabled package pickup can significantly reduce carbon emissions, as well as delivery distances in both urban and suburban scenarios. Ref. [24] proposed a sustainable urban logistics framework to boost the potential use of cargo cycles based on empirical case studies in the United Kingdom. They claimed that local authorities play a critical role in promoting cargo cycles to make them major urban freight transport. Ref. [54] proposed a novel logistics planning model for last mile deliveries based on shared movability, which can characterize open-loop car routes, wage-response properties, and competition in the ride share and delivery services. Refs.