# Value Stream Analysis in Military Logistics:
## 2 Background
### Value Stream Practices  
The origin of the value stream analysis, i.e., value stream mapping (VSM) and value stream design (VSD) methods, is the Toyota production system. It is a visual tool and facilitates the continuous improvement in processes efficiency with the identification of value-adding activities and the elimination or modification of adding waste tasks. Early publications showed during the 1990s the benefits of value stream analysis as an operational approach for a lean enterprise and defined specific lean tools for minimizing the seven wastes [45]. Although it is a simple and standardized methodology, it presents limitations and challenges, as was reviewed in [46]. Generally, four steps should be established to improve a process by using VSM and VSD tools. First, a particular process for a product or product family should be selected due to particular factors (e.g., criticality, impact, efficiency, etc.). Then, value stream mapping starts analyzing and drawing the current state map of the process, where activities with added and non-added value are exposed. The different activities, materials, and information flows are related and schematized in flow diagrams after walking along the actual process. The main key performance indicators (KPIs) of the process, such as lead-time, are usually measured before VSM to establish a reference point of the initial situation. Value-added, non-value added activities, and inventories are evaluated in terms of their time contribution to the lead-time of the process. After VSM, value stream design outlines the idealized solution for improving the studied process to reduce waste, lead-time, work in process (WIP), and inventories. At this phase, KPIs are measured again, and an action list of improvement proposals is attained. To implement the updated procedure progressively, a pilot series can be set up to validate the measures applied. Finally, the work plan and final implementation are carried out. VSM/VSD methodology has been widely applied in multiple organizations and industries. Several articles have been reviewed in the literature, not only considering specific industries [47] but also including different sectors [48; 49]. Processes of a wide number of case studies demonstrated the benefits of this lean technique. For example, from the automotive and transportation industry, [PERSON] et al. presented VSM as an effective tool to systematically analyze a lean supply chain problem [50]. Lead time and cycle time were reduced in process lines of auto-parts [51; 52] and manufacturing cells [53]. Other manufacturing sectors with confirmed performance results after VSM/VSM applications are plastic injected products used in the healthcare industry [54] and textile and apparel companies [55]. Authors in [56] analyzed traditional steel production processes used in appliance manufacturing and demonstrated the suitability of VSM lean technique and simulation models to evaluate the implemented configurations. Additional case studies with VSM/VSD application with satisfactory results were the industrial paint manufacturing case presented in [57] and the fishing net production company of [58]. Nowadays, a new approach of VSM/VSD related to Industry 4.0 is also under study [59], considering the modeling of internal logistics data [60] or integrating the VSM methodology with a system dynamics analysis [61]. Supply chain challenges in the consumer goods sector were addressed in [62] and [63] to improve two particular processes in the wine and agri-food industry, respectively. The success of value stream mapping is, for example, also demonstrated in product development phases [64], logistical system design [65], software development [66], and service industries [67], so that the universality of this lean technique is worthy of note.