## 2 Literature Review
### Historical Data  
The three Baltic States (Estonia, Latvia and Lithuania) were the republics of the former Soviet Union (USSR). Therefore, the companies producing the asphalt mixture in these countries used the \"Dormashina\" (Kremenchuk, Ukraine) and \"Teltomat\" (Teltov-DDR) equipment of relatively low-MC and simple design. These plants polluted the environment, their usage of electricity and heat energy was inefficient, and the control systems were not advanced (without processors and other electronic control units). The statistical data on the operating AMPs were not annually systematically collected and analysed. Thus,  
Figure 6: The variations in the average amount of HMA and WMA mixtures annually produced in a single AMP in Europe for the 12-year period (2005–2016).  
researchers showed their initiative for a certain period and counted the AMPs operating in the Baltic States. The findings were published in scientific reports, dissertations or research papers.  
The economies of the Western European countries have allowed for the rapid implementation of scientific and technical progress in road building. As a result, the increasing demand for high-quality asphalt mixtures and environmental protection has forced the AMP designers and manufacturers to be ready to supply the technological equipment which would meet these requirements. As for the Eastern European countries, and the Baltic States in particular, before the restoration of independence in 1990 and the following decade, the old generation AMPs had still been operating. The dynamics of renewing the AMPs' fleet (Figure 7) shows that, over time, the ratio of the number of the new to old AMPs has gradually increased (from \(t_{1}\)) in the Baltic States, and the total number has decreased (to \(t_{n}\)) due to the purchasing of modern equipment of a significantly higher MC. This qualitative breakthrough has made it possible to significantly improve the AMPs' fleet, which has come close to the requirements raised by other European countries according to the technical indicators.  
For example, in 1982, Lithuania counted 119 AMPs that operated in 45 asphalt production sites of the companies producing and laying the asphalt mixture. These AMPs manufactured 1.95 million tonnes of the HMA mixture. Two years later (in 1984), 48 asphalt production sites were functioning in the country and 135 stationary AMPs produced 2.284 million tonnes of the HMA mixture. Interestingly, in 1982, only five \"Teltomat\" AMPs (with production rates of 80 to 100 t/h) were available throughout the entire country. In contrast, the other 114 units used equipment manufactured by \"Dormashina\", and their production rate was from 20 to 25 t/h. During the period of renovation of the technological equipment, in 1984, there were 14 AMPs made by \"Teltomat\", and the rest (121 units) were manufactured by \"Dormashina\".  
For a long time, the country did not keep records on its AMPs. For a period of 15 years, the author of this article and his colleagues collected data that allowed the determination of 99 operating AMPs in 44 asphalt production sites in Lithuania. Their activity ranged from 1 to 38 years (average 18.8 years). In 1999, 24 \"Teltomat-5\" AMPs operated in Lithuania. For the period 1987-1999, private business companies bought 7 new AMPs: \"Ammann  
Figure 7: The model of the dynamics of renovating the AMPs’ fleet in the Baltic States.  
Euro A240\" and \"160 Global H\", \"Marini MAP 155 E 190 L\", \"Benninghoven AE 150T\", \"Machinery AMO BS 200 / RC120\", \"Maschinen GmbH Telomat-160\" and \"Dormashina D-645-2\", the MCs of which varied from 100 to 240 t/h.