# Minimization of Material Waste Through Maintenance Interval Optimization in Transport Systems
## 2 State of the Art  
In the area of railway circulation optimization, there is a significant research gap. Most scientific publications assume the TSI (European Directives 96/48/EC (high-speed, HS) in Poland called DSU) regulations as supreme and beyond debate. As a result, research related to rail vehicle components is conducted within the scope defined by TSI. However, the technical reviews, which are defined by time and mileage of rail vehicles, are not considered in terms of optimization. The regulations are not yet ready to operate in line with the latest technology--Industry 4.0 and the Internet of Things (IoT)--to dynamically optimize the intervals between technical reviews [4; 5; 6]. The introduction of such optimization, as demonstrated in the introduction, would significantly reduce operating costs and the amount of service waste. The main studies related to TSI focus, for example, on the creation of an equivalent model of the catenary system to assess short-circuit currents and evaluate its compliance with TSI [7], the evaluation of compliance with guidelines regarding noise caused by the wheel-rail contact [8], or systems for real-time condition assessment. The largest group of studies is in the area of condition assessment. It should be noted, however, that the mentioned systems do not provide a solution similar to the one presented in this publication, but they could be used for collecting diagnostic data, which would be utilized by the system developed within this project. In the future, these solutions may possibly be enriched with predictive models. However, due to the core activities of manufacturers (the so-called business core), the risk of developing predictive systems similar to the one being implemented in this project is very low. Since March 2018, the market situation has not changed, showing that manufacturers of diagnostic stations are not expanding their systems to include predictive models [9]. The following systems could be included:  
* Automatic pantograph measuring stations  
This group includes systems primarily used for pantograph technical reviews. These are both systems located in fixed positions, such as at railway repair facilities, and field systems located along the track. Field systems primarily detect pantograph pressure or damage and serve as a control tool for railway operators [10,11]. Stationary pantograph measuring stations, on the other hand, are intended for testing during production processes and are also used in railway maintenance and repair facilities. They measure parameters such as the time it takes to raise the pantograph to its nominal height, the time to lower it, average static pressure, the difference in forces during raising and lowering, and the holding force in the folded state. Measured parameters can be automatically recorded in a database. Additionally, during maintenance, manual measurements of the sliding pad thickness are taken. These systems can determine the technical condition of the device but are not used for predicting its future condition. * Pantograph monitoring systems (in real time)  
Such systems require additional measurement equipment installed on the roof of the rail vehicle [12]. They can be used only to monitor pantograph parameters or to detect damage to the pantograph-catenary system, utilizing additional software for such analysis. These systems mainly operate based on image analysis, requiring cameras mounted on the roof of the rail vehicle. They serve to determine the cause of damage but are not capable of preventing it. Moreover, they are costly and require modifications to the vehicle. There are also systems, like the Australian PCDS (Pantograph Collision Detection System), which detect damage using installed sensors. * OCL monitoring systems (in real time)/Vision Services Oriented (VSO)  
Measurement instruments are permanently mounted on the roof of the rail vehicle or on the pantograph. They are used to measure the geometry of the overhead contact line.