# Dynamic Load Modelling within Combined Transport Trains during Transportation on a Railway Ferry
## 1 Introduction  
In the context of modern development of the transport industry, it is necessary to put into operation the combination of transport systems in order to maintain the leading positions of railway transport. In fact, container transportation is one of the most successful and widespread among combined transport systems. A significant segment of this transport is carried out by sea transport. At the same time, the peculiarities of loading and transporting containers by sea are highlighted in research works [1; 2; 3; 4; 5; 6]. To improve the efficiency of this type of transport, container trains are being transported by sea (see Figure 1). According to the United Nations, the global maritime traffic is projected to grow by 3.8% in 2018-2023 [7]. Traffic is expected to increase across all sectors, with the fastest growing traffic being container and dry bulk traffic. In this connection, the issues of transporting trains of combined transport by sea are relevant. Transportation of container trains by sea is accompanied by loads on them that are not inherent in the operating conditions for the tracks. The typical scheme of interaction between a container and a flat wagon (fittings, fitting stops) in the conditions of fluctuations of the railway ferry does not provide stability of balance. This situation may contribute to violation of combined transport traffic safety [8]. The main causes of ship sinking are technical failures, human factors, route conditions, delivery factors, as well as factors associated with the transported cargo [9]. Natural factors--wind, waves, and sea currents--also have significant impacts on the safety of sea traffic. These reasons often cause a violation of the stability of the vessel and its sinking [10]. The consequences of the sinking of sea vessels, including rail ferries, can be associated with financial losses, loss of life, as well as environmental aspects [11; 12]. It is known that ship accidents cause 14% of oil pollution of the environment. The duration of the existence of an oil slick and slick on the sea surface can reach several months. In addition, oil spills tend to move over considerable distances under the influence of wind and sea currents. Bulk cargo transported by sea is no less dangerous. In case of ship accidents, heavy metals are released into the environment, as well as other materials that negatively affect the ecology of the water area [13]. The study of the causes of the sinking of sea vessels for the transport of vehicles has shown that the main reason for the loss of stability is the displacement of the cargo. For example, in 2002, the rail ferry Mercury-2 sank in the Caspian Sea due to violation of the stability of tank wagons relative to the deck. On board of the vessel were 16 tank wagons with oil products, 1 wagon with consumer cargo, 8 passengers, and 42 crew members. The tank wagons fell off the mountings from the impact of the wave, slid in the direction of the ship's tilt, and caused the ship to sink [14]. Of the people present on board, only nine were rescued and only four bodies of victims of the disaster were found. After 5 days of almost continuous patrolling of the tragedy from the air and at sea, the search activity was stopped by a decision of a specially created government commission. On 5 June 2009, off the coast of the island of Tonga (Indonesia), the cargo-passenger ferry Princess Ashika was lost. The reason for the overturning of the ferry was the shift of the cargo to one side or its incorrect loading while still in the port. On the deck of the ship there were 117 people and cargo (equipment, several ambulances, and trucks) [15]. There is a known case when, as a result of an unreliable anchorage in the Mediterranean Sea during a storm on 8 December 1966, on the Greek ferry ship \"Heraklion\", a refrigerated trailer fell off the attachment and damaged the ferry gate through which water entered the cargo deck. As a result, the ship lost stability, threw on board, and sank [16].