aspects of construction and operation of train ferry routes

Historical Abstract. Sustainable development of the transport industry can be provided through the introduction of combined transport systems. And one of the most promising ones is the train ferry transport system which combines railway and marine transport facilities. The article deals with the analysis and systematization of the data on the historical development of train ferry routes and describes the background for the construction of train ferry routes and their advantages over other combined transport types. It also deals with the basic features of the train ferries operating on the main international train ferry routes. The study is concerned with both sea routes and routes across rivers and lakes. The article shows the role of train ferry routes in the improvement of a national economy, and in the provision of the military defense, as it was described by Vinogradov at the example of Saratovskaya Pereprava (route) and by Karakashly and Shklyaruk at the example of the lighter Ishimbay which was loaded from the side. The authors have analyzed the development of the train ferry routes serviced by the ice-breaking train ferries Baikal across Lake Baikal, and the ferries Sakhalin linked mainland Russia and Sakhalin Island. The article deals with the peculiarities of transportation by trains ferries in the USA, Japan, Azerbaijan, Dagestan, Germany, Lithuania, and some other countries, and presents the analysis of the operational features of Ukrainian train ferries which connect Ukraine with Bulgaria, Georgia, and Turkey. Besides, the article describes some peculiarities of the loading and transportation of passenger trains by train ferries. The study deals with structural peculiarities, and processing technology used for modern train ferries operating across the Black Sea, the Caspian Sea and the Baltic Sea. The research is based on the analysis of works by Egorov (the Marine Engineering Bureau, Ukraine). The research emphasizes the importance of train ferry transportation for the sustainable development of national economies including the economy of Ukraine.

Bulgaria, Georgia, and Turkey. Besides, the article describes some peculiarities of the loading and transportation of passenger trains by train ferries. The study deals with structural peculiarities, and processing technology used for modern train ferries operating across the Black Sea, the Caspian Sea and the Baltic Sea. The research is based on the analysis of works by Egorov (the Marine Engineering Bureau, Ukraine). The research emphasizes the importance of train ferry transportation for the sustainable development of national economies including the economy of Ukraine.
Keywords: train ferry; combined transportation; combined transport; marine transportation; rail ferry route

Introduction.
The rapid development of economic relations between European countries has required reforms in the transport industry. And one of the most effective solutions in this area is the formation of combined transport systems. The maritime countries are integrated into the international transportation system through their train ferry routes serviced by specially equipped vesselstrain ferrieswhich can transfer rail cars by sea. This type of transportation has a great number of significant advantages over the other types of combined transport, among which are the shorter delivery way from consigner to consignee, which can reduce the relative transportation cost; no necessity to transship the freight; less damage and fewer losses of the freight; and faster delivery from consigner to the consignee. The map of train ferry routes has constantly expanded. Modern train ferries with innovative structures and processing technologies have been put into operation. The higher efficiency of this combined transportation can improve the national economy of any maritime country.
The historical development of the most important train ferry routes were analyzed in studies by Sotnikov (1993, p. 84-92). However, the author focused on the geographic features of these routes. Zemlezin (1970, p. 4-12) and Shmakov (1975, p. 87-94) considered the issue of the technical adjustment of rail cars to transportation by train ferries, and described the dynamics of rail cars during marine transportation. In his work Sukolenov et al. (1989, p. 25-34) studied the processing technology for train ferries.
Tolstov studied the peculiarities of construction and operation of the train ferry route across Lake Baikal. He also analyzed the structure and processing technology of the train ferry Baikal. However the author did not describe the other train ferry routes across the lake (Tolstov, 2001).
The development strategy of the railway transport system in the West African Economic and Monetary Union (WAEMU) was studies on the basis of the SWOT/AHP technique by Bouraima (Bouraima, Qiu, Yusupov, & Ndjegwes, 2020). According to the results of the research the authors suggested the strategies for the regional to study the peculiarities of the development of train ferry transportation in the world; and to study the features of development of train ferry transportation in Ukraine.

Research methods.
The basic method used in the research into the historical aspects of construction and operation of train ferry transportation is the historical approach. The research includes the analysis of periodical and historical literature which covers the issues of construction, development and operational prospects of train ferry transportation.

Results and discussion.
The world first train ferry service was launched in 1851; it operated across the Firth of Forth from Granton and Burntisland (Sotnikov, 1993, p. 84).
In Germany the first train ferry service was put into operation in 1882; the 25-km route linked Stralsund and Altefähr.
In 1905 Italy started a train ferry service across the Strait of Messina. It was an 8km route with ten ferries in operation. The distance between the ports Villa San Giovanni and Messina was covered in 40 min.
Later on, in 1961, a train ferry route across the Tyrrhenian Sea was launched; it connected mainland Europe and the Island of Sardinia (Sotnikov, 1993, p. 85).
In 1983 Italy built the double-deck ferry Garibaldi to link the mainland and the Island of Sardinia. Apart from rail cars it transported wheeled equipment. It also had some passenger rooms. Rail cars and wheeled equipment were rolled on through the stern doors equipped with the ramp. The ferry had two elevators that could simultaneously lift 40-ton rail cars to the upper deck or the hold in 30 seconds. The rail cars were distributed on the hold width with a special platform moving along the transverse axis of the ferry.
The ferry was also equipped with a 25-ton crane for elevating 24 containers to the upper deck. The displacement length of the ferry was 137.8 m, the breadth -18.9 m, the draft -5.7 m, and the capacity -80 rail cars. The ferry speed was 20.3 knots (Sudostroenie, 1983).
The ferry Rügen was built in 1972; it could place 37 freight cars. The automobile deck accommodated 12 freight cars or 73 passenger cars. The ferry speed was 20.3 knots (Sotnikov, 1993, p. 85;Serova, 1988). The rail cars were rolled on/off horizontally through the stern ramp. The ferry was equipped with stabilization devices against sea disturbance (Sudostroenie, 1973).
The ferry Rostock, built in 1977, could transport 49 freight cars located on its five tracks. The capacity of the motorcar deck was 21 vehicles. The ferry speed was 20.5 knots (Sotnikov, 1993, p. 85;Serova, 1988).
The ferry Trelleborg was put into operation in 1982 and it had five tracks for rail cars. The full ferry length was 170.1 m and the breadth -22.5 m. Its speed was 19 knots. The total length of the tracks amounted to about 700 m. The ferry could accommodate 55 rail cars. It could also transport 800 passengers. The train ferry Gotland (Sweden) also had five rail tracks (Serova, 1988).
In 1959 the ferry Saßnits was built. Its length was 137.5 m, the breadth along the fender bar -18.8 m. The four tracks on the deck of the total length 380 m could accommodate 30 freight cars. The ferry speed was 12 knots (Serova, 1988).
The ferry Sea Wind (former name Saga Wind built in 1972), re-equipped by Blohm & Voss, German shipbuilding and engineering company, was put into operation from Stockholm (Sweden) to Turku (Finland). The ferry transported rail cars located on the main deck, trucks and automobiles on the upper and boat decks; it also carried passengers. The ferry was equipped with devices for rolling on wheeled equipment. Among them were a stern hydraulic ramp and an inter-deck ramp located on the left side, which connected the upper and boat decks, and a stem gangway on the right side for light vehicles. The ferry length was 154 m, the breadth -21m, and the draft -5 m (Sudostroenie, 1990).
In 1920 the shipbuilding company Bell began to build special ships to transport bulky cargo, including rail cars, by sea.
Thus, the ship Bell Vu transported 22 cars for an electrified railway and two steel barges from England to Buenos Aires. Each wagon weighed 37 tons. In order to save space, the eight cars were located above the barges on the special wooden platforms at a height of 12 feet thoroughly adjusted for the barges, well in advance before they were loaded on the ship.
One of the ships, Beldjan, transported simultaneously 24 rail cars for the underground railway, 20 locomotives, 2 small river tow-boats and engine barges with a length of up to 27 m and mass of 100 tons each. The rail cars were located in two levels (behind the mid-ship superstructure). The height of this construction was the same as the height of the bridge. The upper raw of the rail cars was mounted on the special metal frame. Besides, some types of heavy freight cargo were accommodated in the hold; that managed to compensate the elevated center of gravity (Morskoj flot, 1943).
In 1923 in order to transfer the steam ships of the series E Sch and E Schg from Sweden and Germany to Russia across the Baltic Sea, a ferry service was launched (Lomonosov, 1923, p. 34-45).
The ferry service between Great Britain and mainland Europe has been in operation since 1924. And the first line across the strait was from Harwich (Great Britain) to Zeebrugge (Belgium). The ferry service with France has been in operation since 1936. In 1967 the second ferry service from Harwich (Great Britain) and Dunkirk (France) was launched. It was closed due to construction of the English Channel Tunnel (Sotnikov, 1993, p. 86).
The ferry service from Hirtshals (Denmark) to Kristiansand (Norway) was launched in 1958 with the ferry Skagen. Its length was 80.9 m, the breadth -13.8 m and the speed -18 knots. The journey time was 4 hours (Vinogradov, 1960, p. 12-18). The ferry could carry 7 rail cars placed on a 69-m track, 40 automobiles, and 600 passengers.
Later on, Germany built the train-motor-passenger-electric ferry Teodor Heus. It was intended for service in ice conditions. The ferry had three tracks for 30 rail cars. The middle deck could accommodate 100 automobiles. The passenger capacity of the ferry was 600 passengers with their luggage. The maximum length of the ferry was 135.9 m, the breadth -17.7 m, the hull height -7.35 m, the draft -4.79 m at the water displacement 6438 tons, the traffic speed -16.6 knots (Vinogradov, 1960, p. 18-21).
The ferry service between Travemünde (Germany) and Hanko (Finland) was put into operation in 1975. A three-deck ferry intended for transportation of 65 rail cars was in the service. In 1979 the ferry length was extended, thus, its capacity was increased by 30%. And in 1984 the route was supplied with another ferry (Sotnikov, 1993, p. 86).
Ferry transportation was also introduced in America. The loaded freight cars were transported by the tugboats Dalzell and Transfer (Vinogradov, 1960, p. 21). The tugboats transferred rail cars from station to station along the river Hudson, and also to New Haven. Two ferries loaded with 20 rail cars each were simultaneously towed.
An 18-km route in the Strait of Georgia was serviced by two ferries. They transported both passengers and freight. The journey time was 55 min. One ferry was in operation between Matane and Baie-Comeau (45 km). It transported freight cars. The journey time was 2 hours (Serova, 1988).
In 1964 the longest ferry service in the Pacific Ocean region was introduced between Canada and Alaska (over 2000 km). Double-deck ferries were in service on the route.
The ports Goose Bay and Lewisport in the Atlantic Ocean were linked by a 615 km ferry service. The journey time was 30 hours. The ports Sydney and Port aux Basque were also linked by ferry service. Its length was 164 km. The journey time was 6 hours. The length of the ferry service from Cape Tormentine to Port Borden was 14 km. The ferry transported passengers and freight. The journey time was 2 hours (Serova, 1988).
The route from Somory to Hakodate was serviced by a passenger ferry that could accommodate 1200 passengers and 19 rail cars, and a freight/passenger ferry that was intended for 300 passengers and 45 rail cars.
In 1962 the rolling stock units from Baku to the northern coast of the Caspian Sea were transported in accordance with the working project on the re-equipment of the seaborne barge Ishimbay. It was a dry-cargo one-deck non-self-propelled doublebottom barge intended for transportation of containers, timber, cotton and grain both in rooms and on the deck (Karakashly, Shklyaruk, 1965).
It had 16 rail tracks on the specially designed platforms for the rolling stock units. They were located on the main deck above the hatch covers across the width and were perpendicular to the centerline plane. The platform length was chosen according to the largest dimension of a rolling stock unit with consideration of rolling-on/off from the left side. The vehicles were rolled on from the head to the stern. The rail tracks of the ferry were joined to the port tracks with pads and screws. The first vehicle was rolled on the stem track with a diesel locomotive and a buffer wagon. There were two variants to fasten a rolling stock unit on the barge deck. The first one supposed the chain binders of a 17-mm chain gauge with a special spring turnbuckle damping dynamic jerks from sea disturbance. The binders were fixed with brackets to the special eye plates welded to the frames of rolling stock units, decks, and hatch covers on the barge.
The second variant provided for application of the rigid buckles made of fabricated wagon buckles intended for 30 tons. Wooden wedges were used as supports hammered between the wheel bogie and the frame.
Due to lack of time the second variant was chosen as less labor-intensive in production.
The deck of the barge Ishimbay turned out to be reliable and efficient for transportation.
The shipment across the Caspian Sea was conducted by the ferry Soviet Azerbaijan manufactured by the shipyard Krasnoye Sormovo (Figure 1). (Forum rechnyh puteshestvennikov, 2009).
Later on the train ferries Soviet Dagestan (see Figure 2 (Nash Baku, n. d.)), Soviet Tajikistan (see Figure 3 (Henderson, 2020)) and Soviet Kalmykia were built in Yugoslavia by the shipbuilding company Uljanik for servicing the route between Baku and Krasnovodsk. The ferries had a closed rail car deck along the whole length with tracks for rail cars and the hold for the light vehicles. The rolling-on/off was conducted across the head water-proof doors. The lower deck had a ramp for rolling cars into the hold.
The ferry length was 154.4 m, the fender bar width -18.3 m, the maximum draft -4.5 m, and the speedof 17 knots. The ferry could accommodate about 30 wagons (Frik, 1985).
The wagons were fastened on the decks with the chain binders through the deck eye plates and the wagon frame, and by means of the tension mechanical device Speed Lash with a link length of about 2.5 m and the operating tension 80 kN. Similar devices were used for automobiles and trailers. The automobiles were fastened with soft lashing ropes and deck eye plates with braking strength of 12 kN. The stem part of the lower deck was equipped with four end buffers with a SA-3 automatic coupler. The cars were maintained on the brake by the compressed air system connected to them (Kirsanov, 1985). The impact of the sea disturbance was moderated with the active disturbance control system equipped with the side steering wheels. The system decreased the disturbance amplitude from 19 0 to 4 0 at the speed 17 knots and sea disturbance of 7 points (Kuzovkin, 1984).
The ferries Soviet Kazakhstan and Soviet Turkmenistan were built to link Krasnovodsk and Bekdash (Kargin, 1988). The journey time was 9 hours.
With time the number of ferries across the Caspian Sea totaled thirteen (Zorin, 1988). Among them were Soviet Nakhchivan, Soviet Kirgizia, Soviet Uzbekistan and others.
Besides, the ferry Mercuri-2 operated across the Caspian Sea (see  The innovative technologies of that time were used to allocate rail cars on the ferry. The ferry was equipped with special devices and elevators (Korabli vsekh vremen i narodov, 2017).
The shipbuilding company Uljanik also built the train ferries Makhachkala-4 for operation across the Caspian Sea from Makhachkala to Aktau or Turkmenbashi (see Figure 6 (Korabli vsekh vremen i narodov, 2017)). The ferry length was 154.5 m, the breadth -18.3 m, the draft -4.67 m, and the capacity -52 rail cars. The ferry speed was 14 knots (Informacionnoe agentstvo REGNUM, 2005). It could transport up to 52 rail cars (Gadzhiev, 2005). The Vanino-Kholmsk train ferry service connected mainland Russia and Sakhalin Island. It was launched in 1973. The rail cars were carried by the ferry icebreaker Sakhalin (Figure 7 (Starinova & Shcherbakov, 2018)). The ferry length was 127 m, the breadth -19.8 m, the draft -6.2 m, and the speed -18 knots. The ferry had a rail car http://www.hst-journal.com Історія науки і техніки, 2021, том 11, випуск 2 History of science andtechnology, 2021, vol. 11, issue 2 (main) deck with four rail tracks for rolling stock vehicles. The cars were located by batch on two middle and two side tracks.
The loading/unloading operations were conducted across the ramp rested on the stern step of the deck. The rail cars were loaded with locomotives on two tracks simultaneously, and automobiles were rolled on with their own power (Rachkov, Bubnov, Evstifeev, 1972). At present there exist a great number of such ferries.
Port Borden (Prince Edward Island) and Cape Tormentine (New Brunswick) in Canada were connected with an ice-breaking train ferry. The ferry length was 106 m, the breadth -18.6 m, the draft -5.8, and the speed -16.5 knots. The ferry could accommodate 19 freight cars, 60 automobiles, and 900 passengers (Kilesso, 1945).
The diesel ferry Malmohus connected Copenhagen and Malmo. The ferry length was 94.1 m, the breadth -16 m, the draft -4.1 m, and the speed -17 knots. It was intended for simultaneous transportation of 3100 passengers and freight cars (Kilesso, 1945).
Poland also began to develop ferry transportation. Thus, after WWII the train ferry service was launched between Świnoujście and Sweden with only one ferry. In 1953 the ferry service suspended for some period. And in the mid-1960s it was resumed with passenger-automobile ferries.
The ferry route from Świnoujście to Ystad was serviced by the ferries Nikolaus Copernicus and Johannes Hevelius manufactured in Norway in 1973 and 1975, respectively. The train ferries transported rail cars and trucks. They make several runs per day by necessity (Wojewódka, 1979).
They were double-deckers and could transport 103 rail cars. For the first time, the revolutionary loading/unloading technology of that period was used for the route. With its two decks, the ferry joined a 45-m suspension double-deck ramp. The ramp was the front part of a 175-m platform. Each level had five rail tracks similar to those on the decks. Two decks cannot be loaded simultaneously as it could cause loss of stability.
The speed of the locomotive used for loading/unloading operations was 1 m/sec. An automated anti-tilting system was used for maintaining stability within a range of 3 0 during freight operations (Shishin, 1986).
In 1989 the new Ro-Ro/Rail/Passenger ferry Kaunas was put into operation ( Figure 9 (Informacionnoe agentstvo QIRIM HABER AJANSI, 2017)). The vessel was supervised by the Lloyd's shipping registry. The full length of the ferry was over 190 m and the breadth -28 m. Two freight decks could simultaneously accommodate 49 universal rail cars and 50 heavyweight trucks TIR (Informacionnoe agentstvo QIRIM HABER AJANSI, 2017).   and technology, 2021, vol. 11, issue 2 In 2006 the ferry service between Ust-Luga and Baltiysk was put into operation. It was serviced by the train ferry Baltijsk (Figure 10 (Korabli vsekh vremen i narodov, 2015). The ferry length was 187.36 m and the breadth -22 m. The total length of the rail tracks was 1943 m. The capacity of the ferry was 135 rail cars (the length of couplers' axles was 12,020 m) or 92 rail cars (the length of couplers' axles was 16,970 m). Besides, the ferry could carry 76 automobiles on the open upper deck. The ferry speed was 18.5 knots.
The ferry had three freight decks with five rail tracks each. The loading of the middle deck was conducted through the stern doors. Rail cars and wheeled equipment were lifted up and put on the upper and bottom decks with a double-deck elevator with a freight capacity of 94 tons. The upper and lower elevator's platforms had freight areas of the length 28 m with clamping grips for the car wheels and holes to fix lashing ropes.
The cars were transferred on the decks with rotating hands installed in the stem part of the upper and bottom decks. The ferry was also equipped with seven shipboard trailers. The rolling-on/off of the freight in ports without dock ramps was conducted with special removable ramps mounted on the stern area with special holes for lashing ropes of hydraulic winches on the middle deck on the left and on the right. A set of removable ramps could be stored in ports or on ferries (Egorov, Kuzmin, & Ilnitskij, 2006;Kuzmin & Egorov, 2006).
Later on the ferries Ambal (Figure 11   The ferry services from Romania to Turkey and from Romania to Georgia, which shortened the distance by 340 km and 1075 km respectively, used the three-deck ferries Mangalia and Eforie belonging to the state-owned freight railway business of Romania CFR Marfă. These ferries could carry 85 -100 rail cars located on the deck's rail tracks with a distance of 1435 mm between the running edges of rail heads; the total length was 1680 m.
The ferries had a lift for transferring rail cars from the middle deck to the upper or bottom decks, and a deck crane of five rail tracks for fitting with the on-land rail track infrastructure. To transfer rail cars from one track to another the ferry decks were equipped with one movable platform on each deck. Besides, the ferry had a switching device for shunting operations.
The ferry service was launched across the Black Sea in the middle of the 20 th century. In 1958 the European and Asian shores of Turkey across the Bosporus Strait were connected between the ports Sirkeli and Haydar (Egorov, Ilnitskij, & Chernikov, 2014).
In March 1955 the ferry service connected Ukrainian and Russian Republics of the former Soviet Union.
Two train ferry complexes between the stations Crimea and Caucasus were built to shorten a journey time of mass freight transportation between the republics. That train ferry service shortened the distance up to 1000 km, and relieved the Rostov railway junction.
Due to a short distance of about four kilometers, the ferry service across the Taman Bay was considered to be rather safe for the rolling stock units, despite the harsh climatic conditions in that region.
As far as Kerch has always been a cross-road of great merchant routes from Europe to Asia, from the Varangians to the Greeks and one of the Great Silk road, the Crimea-Caucasus train ferry service has always been an important link in the transport corridor connecting Ukraine with Russia, Kazakhstan, countries of Caucasus and Central Asia by means of the sea rail ferry routes in the Caspian Sea: from Makhachkala to Aktau and from Makhachkala to Turkmenbashi (Chikanovskij, 2004).
At first the route was serviced by four train diesel electric ferries: Yuzhny (Figure 13), Eastern (Chulym and Nadym, respectively (Proekt 723 (zheleznodorozhnye paromy, n. d.)), Northern and Zapoliarny. These ferries were intended for transportation of 16 freight cars. After the collapse of the Soviet Union in 1986, the volume of transportation via the route considerably decreased and later on it was closed. It was not until October 2004 that the ferry service was resumed due to the combined efforts of Ukraine and Russia (Egorov, 2007;Sudostroenie i sudoremont, 2004).
The ferry decks have four rail tracks for location of rail cars. The ferry length is 110.5 m, the breadth -16.0 m and the draft -3.2 m. The speed of the train ferry is 10.0 knots (Nastavlenie po krepleniyu gruza, 2005).
Due to a constant increase in the freight turnover during the recent years, there has been a need to increase the throughput capacity of ferry transportation. In 2007 the one-deck ferries SMAT and FERUZ (Figure 15 (Morskoe Inzhenernoe Byuro, Proekt CNF03.01, n.d.)) with the capacity 50 tank cars 1-T with five tracks on the ferry deck were built for the ferry routes Caucasus (Russia) -Samsun (Turkey) and Caucasus (Russia) -Poti (Georgia) (Egorov, Chistjakov, & Avtutov, 2007;Efremov & Egorov, 2007).
On the basis of the analysis of positive results of the existing train ferry routes and due to the strategic targets, on the 23 rd April 1975 the Soviet Union and Bulgaria signed a Treaty on organization of ferry service between the ports Illichivsk and Varna to be put into operation in 1978 (Nejding & Korotkij, 1978;Jovchev, 1984).
The port infrastructure for the ferry routes was built by the construction company Chernomorhydrostroy, and the rail infrastructure facilities were built by the construction company Odessatransstroy. One of the major features of the port Illichivsk was its advantageous position on the cross-road of main transport routes between Europe and Asia, North and South, Central and Eastern Europe, industrial regions of Russia and Ukraine, and naval communications via the Mediterranean Sea to the Atlantic and Indian Oceans (Fomin, Lovska, Píštěk, & Kučera, 2019), (Fomin, Lovska, Píštěk, & Kučera, 2020).
The ferry routes Illichivsk -Poti (opened in 1994) and Illichivsk -Batumi (opened in 1996) are serviced by the Ro-Ro/passenger ferry Greifswald (Figure 17) supervised by the Lloyd's shipping registry.
The ferry was built by VEB Mathias Thesen Werft in Wismar (Germany) in 1988 and it serviced the route Rostok (Germany) -Klaipeda (Lithuania).
The ferry length was 190.8 m, the breadth -26.0 m, and the draft -6.0 m. The speed of the train ferry was 16 knots (Cargo securing manual Transocean Line a/s ms "Greifswald", 2001). Figure 17. Train ferry Greifswald a) side view (author's photo); b) main deck (author's photo).

а) b)
In 1996 the ferry was re-equipped and a passenger complex was added. The ferry had two freight decks that could accommodate 103 rail cars, but due to the structural features of the loading complexes in Illichivsk and Poti/Batumi, only 50 cars could be placed on the main deck. Besides, it could accommodate 50 heavyweight trailers on the deck, which was an advantage regarding bimodal transport, contrailer transport and other combined transport systems.
It should be noted that potentially the ferry could accommodate 103 rail cars, but as far as they could be accommodated only on the upper deck (due to the structural peculiarities of the loading complexes in Illichivsk and Poti), only 50 cars could virtually be loaded.
Since 2001 the ferry route Illichivsk (Ukraine) -Derince (Turkey) has been in operation with the ferries Geroi Shipki and Geroi Plevny.
The ferry had the certificate of the Guinness World Records on being the biggest world passenger/Ro-Ro/railway ferry (Mihajlova, 2013). In 2009 the group of companies AnRussTrans built the train ferries Avangard for 45 rail cars (Figure 19 (Klimenko, 2012)) and Slavianin for 50 rail cars (Figure 20 (Klimenko, 2012)) with accordance to the project of the Marine Engineering Bureau. Figure 19. Train ferry Avangard (Klimenko, 2012).
The length of the train ferry Avangard was 133.67 m, the breadth -22 m, and the draft -4.8 m. The ferry speed was 12 knots.
The length of the train ferry Slavyanin was 149.95, the breadth -22 m, and the draft -4.5 m. The ferry speed was 12 knots.
Train ferries transported not only freight, but also passenger cars, thus they could offer seamless transportation for passengers which were accommodated in passenger rooms. And today this type of transportation is very popular. For example, the train ferries operating across the Baltic Sea can offer this service (Klochenko, 1988). Formerly, passenger cars were placed on the deck by means of hoisting devices from the tracks of the ferry complex to the ferry's tracks. And now the cars are rolled through the ramp, which has considerably shortened the loading/unloading time. http://www.hst-journal.com Історія науки і техніки, 2021, том 11, випуск 2 History of science andtechnology, 2021, vol. 11, issue 2 Besides, train ferries became popular for river transportation. From 1896 to 1935 there was a ferry service across the Volga River near the town Saratov of the Ryazan-Ural Railway (Ivanchenko, & Platonov, 1943, p. 20) with the ferry Saratovskaya Pereprava (Figure 22 (Smorodin, 2013)). The ferry was built by the British manufacturing company Sir W. G. Armstrong Mitchel in 1896 (Volkov, 1977). The ferry had a hydraulic elevating mechanism for delivering cars from the ramp to the deck. During navigation seasons the ferry transported 160 cars per day, they were rolled on its deck. In winter seasons it transported 120 cars at shuttle service (28 cars per run). (Smorodin, 2013).

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The route was also serviced by the ferry Saratovsky Ledokol to break ice and transport passengers and freight (Smorodin, 2013).
From 1903 to 1915 between the harbors Baikal and Tankhoy there was a ferry service across Lake Baikal on the Trans-Siberian route. The icebreaker ferry Baikal transported 27 rail cars. Its average speed was 18 km/h in summer and less than 11 km/h in winter. The ferry design was similar to that of the American icebreaker operating on Lake Michigan.
It was built in 1896 and had the biggest water displacement among the existing icebreakers at that time (Kilesso, 1945).
The year 1918 saw the last voyage of the icebreaker Baikal (Figure 24 (Shoemaker, 1903, p. 99). By its decision the Irkutsk Rada organized the Red Baikal Fleet to fight against the counter-revolutionary movement. It was damaged by field artillery fire, burnt and sank during a battle (Tolstov, 2001).  (Shoemaker, 1903, p. 99).
In the period from 1926 to 1936 there was a ferry service between the towns Gorky and Kotelnich. The ferry had a reinforced concrete body intended for breaking ice (Volkov, 1977).
Later, on the Komsomolsk-Pivan section across the Amur River a 7-km ferry service was put into operation with the train ferries Volga and Don (both built in 1951), and Amur and Komsomolsk (both built in 1951). They were river ferries with an open deck and a wagon hoist in the head section. The wagons were located in four lines and http: //www.hst-journal.com Історія науки і техніки, 2021, том 11, випуск 2 History of science andtechnology, 2021, vol. 11, issue 2 lifted with an 80-ton device with a hoist height of up to 5 m. The wagons were transferred on the deck with trailer bogies, ropes and winch generators installed at the end of each track (Volkov, 1977).
In 1939 across the Danube River the cities Ruse and Giurgiu were connected with the ferry service for automobiles and rail cars. This route is now operable though it is not used (Telov, 2006, p. 10).
In 1941 during World War II there was a ferry route across the River Volga. A twin-hulled ferry transported rail cars. The wagons were rolled on simultaneously from two port tracks with a gradual transfer of the ferry along the dockside with two 5-ton wrenches installed in the dock at a distance of 100 m. The train ferry had 18 tracks and each could accommodate three double-axle or two four-axle rail cars, or a steam locomotive with a tender. The cars were rolled on through two suspension linkspans installed on the pier (Kupenskij, 1988).
In 1909 Norway had a train ferry across Lake Tinshe between Tinnuset and Mel. Its length was 28 km. The journey time was 1 hour 20 minutes.
Since 1964 Turkey has operated a train ferry between the ports Tatvan and Van. Its length was 90 km with two train ferries in service.
A train ferry operated between the ports Thunder Bay (Canada) and Superior (US) across Lake Superior. The route length was 285 km. The journey time was 14 hours (Serova, 1988).
There were two train ferry routes across Lake Michigan (US): Ludington -Kewaunee (105 km) and Ludington -Manitowoc (104 km). Each line operated one ferry; the journey time of each was 4 hours.
Since 1971 South American countries Peru and Bolivia have been connected with a ferry service across Lake Titicaca (Serova, 1988).
Since 1983 a ferry service has been in operation across Lake Victoria between Uganda and Tanzania in Africa. Its length was 400 km. In 1985 the line was supplied with two ferries. Their length was 92.13 m and the breadth -16.5 m each. Each carried 22 freight cars and 5 containers. They could also carry passengers and freight.
Apart from Uganda, ferry transportation across Lake Victoria was carried by Tanzania and Kenya (Serova, 1988).
The research allowed systematizing the historical aspects regarding the construction of the biggest and most important train ferry routes. Unlike the studies by Sotnikov the authors conducted not only systematization and analysis of the geographical allocation of train ferry routes, but also investigation into the technical peculiarities of train ferries which serviced these routes (Sotnikov, 1993, p. 83-90). The authors considered both European train ferry routes and international ones (Fomin & Lovska, 2020) and (Parkhomenko, Viznyak, Skurikhin, & Eiduks, 2020), and defined the background of their construction. This was not covered in earlier publications, such as (Tanko & Burke, 2017), (Merrill, Paz, Molano, Shrestha, Maheshwari, Haroon, & Hanns de la Fuente-Mella, 2016). The authors studied both freight transportation and passenger transportation, which was not presented in the study (Mańkowska, 2015). Therefore, this research presents the analysis of the historical background and efficient operation of train ferry routes (for transportation of freight and passengers) and proves the unique nature and importance of this type of combined transportation for development of national economies of the maritime countries.

Conclusions.
The research deals with the background for the development of train ferry transportation. It was found that train ferry transportation is advantageous over other types of combined transportation. The first successful train ferry routes encouraged engineers to develop much longer seaways, and at present, there are train ferry routes that connect countries.
The authors studied the peculiarities of the development of train ferry transportation in different countries. Successful transportation across the Baltic Sea (at the example of one of the first train ferry routes between Stralsund and Alterfähr) encouraged the specialists to develop and expand the geography of such routes to other seas: the Caspian Sea, the Black Sea, the Azov Sea, the Japan Sea, the Mediterranean Sea, and some others. Besides, such type of combined transportation was used across lakes and rivers.
The study is concerned with the development of train ferry transportation in Ukraine. It deals with the historical background for the construction of the first train ferry route, and the development of train ferry routes between Ukraine and other countries of the Black Sea. The authors analyzed the technical peculiarities of train ferries and their processing technology.
The research proves the importance of train ferry transportation for the development of national economies (including Ukraine) in the modern world.

Funding.
This research was conducted within the project for young researchers "Innovative approaches in designing resource-saving railway structures with refined dynamic loading characteristics and functional-adaptive flash-concepts"; it was supported by the 2020 State Budget of Ukraine.

Conflicts of interest.
The authors declare no conflict of interest.