## 3 Solutions for Different Points of Optimization in Urban Cold Transportation
### Overview of Solutions Found in Current Logistics Literature
Considering the urban freight fleet composition problem, green variants that reduce the life cycle emissions of fleets do not presently exist, though the data and methodologies are available. However, some algorithmic solutions to reducing the environmental impact of urban freight fleets do exist, examples of which are presented below. Notably, we were unable to find research combining route and load optimization for freight fleets. The optimization of fleet-wide operations should be investigated further in the future. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Proposed Algorithm** & \
\begin{tabular}{c} **Traffic** \\ **Prediction** \\ \end{tabular} &
\begin{tabular}{c} **Traffic** \\ **Control** \\ \end{tabular} & **Where/How Is It Applied?** \\ \hline Stacked Autoencoder [21] & X & & \\ \hline DNN-BTF [22] & X & & \\ \hline Ant Colony Optimizer [23; 24] & & X & Via Internet of Vehicles \\ \hline Bee Colony Optimizer [25; 26] & & X & \\ \hline Adaptive algorithm in a smart traffic light [27] & & X & In the traffic light \\ \hline Two-stage hybrid algorithm [28] & X & & When the refrigerated truck is finding the optimal route \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Different algorithms proposed as solutions to predict or control traffic and how they would be applied. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Solution** & **Type of Solution** & **Problem** \\ \hline Extended load-dependent vehicle routing problem [30] & New type of model for solving VRP & \begin{tabular}{c} VRP that specifically includes \\ refrigeration-related emissions \\ \end{tabular} \\ \hline Random forest regressor and decision tree regressor [31] & \begin{tabular}{c} Machine learning algorithms used to \\ optimize vehicle characteristics based on \\ temperature and humidity in time to \\ reduce product degradation. \\ \end{tabular} & \begin{tabular}{c} The humidity and temperature fluctuate \\ in cold transport vehicles, causing \\ perishable goods to spoil. \\ \end{tabular} \\ \hline Multi-vehicle cooperative bin packing problem [32] & \begin{tabular}{c} Determines packing order of goods \\ between multiple vehicles to increase \\ space utilization. \\ \end{tabular} & \begin{tabular}{c} Vehicles are not packed optimally, \\ resulting in less efficient operations and \\ more emissions. \\ \end{tabular} \\ \hline Real-time anomaly detection [33] & \begin{tabular}{c} Sends out an alert if the perishable goods \\ in transport are in danger of spoiling due \\ to temperature fluctuations. \\ \end{tabular} & \begin{tabular}{c} The temperature fluctuates in cold \\ transport vehicles, causing \\ perishable \\ goods to spoil. \\ \end{tabular} \\ \hline Anomaly prediction using big data [34] & \
\begin{tabular}{c} Algorithmic data analysis to identify and \\ predict reasons for the spoilage of goods \\ \end{tabular} &
\begin{tabular}{c} A variety of reasons can cause the \\ temperature of a refrigerated vehicle to \\ diverge from the required bounds, \\ leading to the spoilage of goods. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Different solutions for minimizing the emissions of refrigerated transport in urban areas. Aside from the identified optimization areas, it is relevant to note that the global market environment affects the capacity of a company to execute its operations efficiently and reliably, meaning that the environmental performance of a cold chain operation is also significantly affected by the markets surrounding them. While the resilience of cold chains has been studied in both business-as-usual [40] as well as exceptional [41] circumstances, the goal of these studies has historically been primarily to identify ways to prevent operation disruptions and economic losses. A literature review of cold chain management [5] found that while food cold chains are globally trending towards adopting sustainable practices, this is mostly taking place in developed countries.