INOM EXAMENSARBETE TEKNIK,GRUNDNIVÅ, 15 HP

, STOCKHOLM SVERIGE 2020

Maglev deployment in winter climateChallenges and solutions for maglev in regions of snow, ice and low temperature

AXEL THORSTRAND

KTHSKOLAN FÖR TEKNIKVETENSKAP

Maglev deployment in winter climate

Sammanfattning

År 2020 har ännu inga maglevsystem byggts i regioner med tufft vinterklimat. Jämfört med konventionell järnväg så är tekniken relativt otestad mot snö, is och låga temperaturer. Om maglev skall användas i dessa regioner måste effekterna av ett kallt klimat på tekniken undersökas.

Låga temperaturer skapar generellt problematiska förändringar i materialegenskaper. Ett exempel är dämpare, vars dämpningskonstanter kan förändras drastiskt då komponenten utsätts för varierande temperaturer. Is på tågets yta kan leda till ökat luftmotstånd och turbulens runt vagnarna. Samma isklumpar kan falla av tåget i höga hastigheter vilket kan leda till stor skada på både vagnar och tågbana. Snömoln som uppkommer av tågets turbulens kan leda till snöansamlingar, framförallt under tågvagnarna, och snöpartiklarna kan ta sig in i känsliga system som ventilationsutlopp.

Många lösningar som används för konventionell järnväg är också applicerbara för maglev. Det finns dock ett antal unika utmaningar för tekniken, som främst har med de höga hastigheterna och den unika typen av tågbana att göra. Luftmotstånd och turbulens ökar matematiskt fortare än hastigheten, och höga hastigheter medför även större krafter. Det leder till ökad vikt av att hålla tågen isfria. De tågbanor som maglev använder är ofta byggda av betong som är känsligt för både frostsprängning och erosion. Även där finns unika utmaningar.

Japan är ledande inom maglevteknologin och har tagit fram en del lösningar för att bekämpa denna typ av vinterproblematik i sina system. De leder bland annat sina maglevbanor genom tunnlar eller höjer upp dem på viadukter för att undvika snöansamlingar. För de delar av spåret där tågen måste åka utomhus används vindskydd mot snö och vind. Vattenspridare med varmt vatten används för att smälta den snö som trots detta hamnar i spåren.

Maglev deployment in winter climate

Abstract

As of year 2020, maglev train systems are not in service in areas with harsh winter climate. Compared to conventional railway, the technology is relatively new and untested in conditions of low temperatures, icing and snow. If maglev is to be deployed in areas of cold climate, the effects on the technology under these conditions must be investigated.

Low temperature pose problems for materials in general as material properties change. One example is dampers, whose damping constants can change drastically with temperature. Icing on the train vehicles cause increased turbulence and drag and chunks of ice can come loose of the vehicle and cause great damage to both the rolling stock and the guideway around it. These issues are especially problematic at the high speeds that maglev trains can reach, as aerodynamic forces often increase faster with greater velocities. Atomized snow in the air caused by the train’s turbulence can pile up on the bogies and around sensitive areas like ventilation inlets.

It is found that many solutions that are used for railway trains can be applied to the maglev technology as well. However, there are some unique challenges for maglev trains. High speed forces, advanced guideway switch management, and frost wedging of the guideways are a few examples. Japan is the leading country in the maglev technology as of 2020, and they have some suggested solutions for cold climate issues for their superconductive maglev. For example, much of the guideway is lead through tunnels, as to not expose the vehicle and guideway to snow. In outside portions, water sprinkler systems and protective hoods are utilized to keep the guideway clear of snow.

Maglev deployment in winter climate

Preface

This report was written during exchange studies in Japan and for that reason it mainly focuses on Japanese sources and material. The topic was however chosen with this in mind since studies in Japan provided a great opportunity to study a technology that the country is world leading in. The author has moderate Japanese language knowledge which has been of great use to this report.

First and foremost, I want to thank my supervisor Mats Berg who has taken the time to read through this report several times and provided great feedback. Mats has also helped me find sources and evaluate which questions i should investigate further.

Many thanks to Annika Stensson Trigell as well. She welcomed me into the course despite my delayed start and exchange study condition. Thanks to Nina Wormbs and Susann Boij who managed the sustainability and innovation modules of the bachelor thesis course.

I want to thank my friends Obata Sae and Ihoroi Natsuho for helping me translate some Japanese sources of information that were overwhelming and difficult for me to grasp at first.

I also want to thank the Sweden-Japan Foundation who has granted me financial support for my exchange studies. The support has allowed me to study the maglev technology closer to its technological frontier.

Maglev deployment in winter climate

Table of contents

1. Introduction 1

1.1 Background 1

1.2 The purpose of this report 1

1.3 Limitations, constraints and sources 1

2. The magnetic levitation technology and its application in trains 2

2.1 History 2

2.2 Why maglev? - Why not? 2

2.3 Electromagnetism - the foundation of magnetic levitation 3

2.4 Electromagnetic suspension (EMS) 4

2.5 Electrodynamic suspension (EDS) 5

3. The effects of snow, ice and low temperatures on the maglev train technology 6

3.1 Heavy snowfall - problems 7

3.2 Heavy snowfall - solutions 8

3.3 Ice - problems 11

3.4 Ice - solutions 13

3.5 Low temperatures - problems 14

3.6 Low temperatures - solutions 14

4. Conclusions 15

5. Further research 15

Bonus chapter: Is the maglev technology environmentally sustainable? 16

References 17

Maglev deployment in winter climate

1. Introduction

1. 1 Background

Rail vehicles carry many benefits over road, sea and air transports. Railway is deemed crucial for most countries to handle the transportation of goods and people.

In Sweden, there are many voices claiming that the current railways are too old and has too low capacity to handle to countries needs. This issue is not set to fix itself since the total travelling in Swedish society is expected to increase by 32% until 2040 and by 47% until 2060. [1] The debate on

what type of train and tracks are suitable has been heated during the 2010’s.

As of today, most of sweden's rails are shared by freight trains and passenger trains. These two types of trains travel at different speeds, leading to longer travel times for both. This is because they have time slots that they need to stay within to not disrupt other traffic.[2] Separating freight trains from

passenger traffic is a good idea, since it will increase the effectivity of both of them. New high speed rail is one option, but there are other options being explored and developed in the world.

In Shanghai, a maglev train transports passengers from Pudong International Airport to the Shanghai city centre at high speeds. A magnetically levitated Shinkansen is currently being constructed between the cities Tokyo and Nagoya in Japan, set to be completed in 2027. It will reduce the travel time between the two cities from 90 to 40 minutes. [3] Looking forward, SpaceX in

the USA have developed what they call “hyperloop” technology. It is an extension of the maglev technology, with the difference that the trains run in nearly air-free (vacuum) tunnels to minimize air resistance.[4] The maglev technology has been proven viable and shows great promise for the future. If we want to explore a possible application of maglev technology in Sweden and in other countries close to the polar circle, the effects of snow, ice and low temperatures on the technology must be studied.

1.2 The Purpose of this report

The purpose of this report is to explore the main components of magnetically levitated trains and their tracks to investigate how they are affected by winter climate factors. Potential Issues for the maglev technology in a climate where snow, Ice and low temperatures are abundant will be explored. The report is meant to serve as a supporting document when planning for- and designing maglev tracks and rolling stock for regions with harsh winter climate.

1.3 Limitations, constraints and sources

This report mainly focuses on the German/Chinese Transrapid technology, the Japanese superconductive maglev technology (SCmaglev) and the Japanese low speed maglev technology (Tobu Kyuroku Line, Aichi). As of 2020, they are the most extensive appliances in the world and therefore seems to be the most realistic choices for a potential application in the suggested cold-climate areas. Future technologies like the Hyperloop will not be explored.

1

Maglev deployment in winter climate

The report will not take into consideration whether or not maglev technology is a viable solution for the population and economics in Sweden and the nordics.

2. The magnetic levitation technology and its application in trains

2.1 History

Patents for different variations of the maglev technology can be traced all the way back to the 1930’s.The person who many consider to be the inventor of the maglev train technology is Hermann Kemper, who conducted research on the topic during the 1920s and 30s. He received a patent in 1934 for what he called a “monorail vehicle with no wheels attached”. [5] The first commercial maglev line was not taken into operation until 1984. It ran between Birmingham international Airport and the nearby railway terminal but was discontinued in 1995 because it was concluded as unreliable. [6] The track was only 588m long [7] and operated at a maximum speed of 42 km/h.[8]

The earliest built maglev line still in operation is the “Shanghai maglev” that transports people between Shanghai´s international airport and the city of Shanghai. The line is 30km long and started its commercial operation in 2003. It uses the German Transrapid technology. The Shanghai maglev can reach a top-speed of 430 km/h, which showed the world the true potential of the technology’s high-speed capacity. [9] Another early contender is the “Linimo” line in Nagoya, Japan. It was built for the 2005 Japan expo and now serve the locals as a 9 km long public transport. With a maximum operational speed of 100 km/h, this is an example of a maglev that operates at relatively low speeds. [10]

Currently, a magnetically levitated Shinkansen is being constructed between the cities Tokyo and Nagoya in Japan, set to be completed in 2027. It will reduce the travel time between the two cities from 90 to 40 minutes.[3] This Line, called the Chuo Shinkansen, uses state-of-the-art superconductive magnet technology that lets the train travel at speeds up to 600 km/h. Currently, a part of the track in the Yamanashi region close to Mt. Fuji is in operation and is being used as a test track. This experimental track will be connected to the finished 285 km long track between Tokyo and Nagoya. [11]

2.2 Why maglev? - Why not?

Magnetically levitated trains carry some benefits over conventional railway trains. The most notable difference is the fact that the levitation creates a gap between the vehicle and the guideway, eliminating the effects of friction. In theory, this makes the vehicle more efficient and gives it a higher possible top-speed. In addition to this, conventional railway tracks are subject to rain, snow, ice, leaves, dust, etc. that create a wide range of friction coefficients. This is not optimal for a system that needs to be stable and punctual. For example, some of the mentioned conditions might cause longer deceleration distances, leading to the train having to operate at lower speeds overall. This is not an issue for a levitating train, since braking is also done with electromagnetic forces. Another advantage of the elimination of slip is an increased range of climb and descent angles for the track. Passenger comfort is another great positive aspect of the magnetic levitation. The lack of connection to the ground reduces noise and vibrations that are traditionally caused by the wheels´ contact with the rail and its imperfections.

2

Maglev deployment in winter climate

There are of course downsides to the technology, with the main one being cost. The technology is not widely applied in the world, and therefore data and experience is limited. The components are also not as widely available as for conventional rail-bound trains. The high operational speeds also pose challenges. For example, aeroacoustic noise becomes a bigger issue since it increases exponentially with higher velocity[12] High speeds also impose greater forces, which puts extra importance on passenger safety and mathematical safety factors. Swedish Trafikverket (Swedish traffic administration) lists their biggest issue with the maglev technology as the lack of possibility of connecting it to the conventional rails. They also point at the low number of current applications in the world and the general low level of experience of the technology.[13]

2.3 Electromagnetism - the foundation of magnetic levitation The force that allows the train to levitate is electromagnetism. It can quickly be concluded that snow and ice do not interfere with the magnetic field itself, as only rotation of- and distance between the magnets has an effect on the magnetic strength. If the medium between the magnets would have magnetic properties, that could cause disturbances. Since water only has very weak diamagnetic properties, this is not an issue. Temperature is however an important factor when it comes to an electromagnets performance. Conventional maglev trains like the Linimo and transrapid uses electromagnets with an iron-based core.[15] If we exaggerate a cold climate by using the lowest temperature ever recorded on earth, -90oC, the electromagnets power would degrade by around 40% compared to a 0oC environment. This is a quite severe loss in power, but considering that more realistic temperature on a very cold day in Sweden would be -35oC, the degradation would be closer to 20%.[15] The data can be seen in Figure 1. This is a loss that could easily be made up for with a temporary increase in electric current. Interestingly, if a coil with superconductive capacity is utilized and the temperature is lowered even further down, to around -269oC, a sharp increase in electromagnetic potential per invested unit of current can be observed. See Figure 2. This has to do with the fact that as the temperature approaches 0K, the resistance in certain materials also approach 0 . This technology is used in the Chuo Ω Shinkansen in Japan mentioned previously, where coils made of Niobium-titanium alloy are cooled by liquid nitrogen to reach those very low of temperatures.[16] This technology will be explored further in the chapter about EDS, electrodynamic suspension.

3

Maglev deployment in winter climate

Figure 1. The effect of temperature on iron-core electromagnets [15]

Figure 2. A simplified figure of the quick plummet in resistance for a superconducting circuit.[16]

We have now concluded that the effects on the magnetism are not that great. There might however be structural issues that are relevant, like snow and ice being in the way or causing problems for the surrounding technologies. Therefore, we must dive deeper into the different layouts of the electromagnetic systems. There are two widely applied technologies that will be analyzed in chapter 2.4 and 2.5 below. 2.4 Electromagnetic suspension (EMS) The first layout to be analyzed is electromagnetic suspension. This electromagnetic control system is used in the Transrapid and Linimo trains that are both operational to date.[14]

At the essence of electromagnetic suspension is a feedback control, continuously measuring the current distance between the track and the train’s magnet module to create a constant gap between them. See a simplified figure below (Figure 3).

4

Maglev deployment in winter climate

Figure 3. A simplification of an EMS feedback system in a maglev train[17]

The gap between the magnet coil and the track is measured and sent to the magnet driver where the current is altered respectively. In the Japanese Linimo this gap is 8 mm[10] and in the Shanghai transrapid the distance varies between 8 and 12 mm.[18] Due to its constantly changing state, EMS systems are inherently unstable. The propulsion in the EMS configuration is provided by a linear electric motor.[10]

2.5 Electrodynamic suspension (EDS) The electrodynamic suspension varies quite a lot from EMS. The technology is used in the Chuo Shinkansen that has previously been mentioned. While the EMS system utilizes feedback to remain in a stable position, a maglev train using the EDS system naturally converges toward the middle of the track. The Central Japan Railway Company gives the following explanation: “Even when the rolling stock leans closer to one side, the magnetic force that acts between superconducting magnets and the Levitation and Guidance Coils keep the train centered in the guideway at all times. The magnetic force prevents the Superconducting Maglev from crashing into guideway walls and contributes to stable operation.” [19]

Basically explained, when the train moves toward one side of the track, it will be repelled by the side it approaches. The rolling stock is pushed into the middle of the track from both sides. The levitation works with the same configuration. The train is repelled from the bottom of the coils and attracted by the top of them. See Figure 4. The configuration of these coils can be seen in Figure 5, the “levitation and guidance coils”. This configuration allows the train to levitate around 100 mm over the guideway.[19] One downside of the EDS configuration is that this stable levitation can not be obtained below speeds of around 150 km/h. Before that it rolls on rubber wheels.[22]

5

Maglev deployment in winter climate

Figure 4. Breakdown of magnet polarities for levitation and centering of an EDS train.[58]

The propulsion of the train is controlled by a second set of coils in the track, namely the “propulsion coils” (the rounded coils in Figure 5). The superconductive coils inside the train is pulled by the coils in front of it and repelled by those behind it.[21]

Figure 5. An illustration of a slice of track from the Chuo Shinkansen.[21]

The reason Japan landed in the EDS system for their high speed trains instead of the EMS system is that the technology was not deemed developed enough until 2009. The Tokyo-Nagoya line was set to be built in 2011.[22] The technology is also more resistant to earthquakes, which Japan has a lot of, as it is inherently stable and levitates with a bigger gap between the rolling stock and guideway.[23] The Chuo Shinkansen also outperforms the Transrapid technology in acceleration- and deceleration speed. This is a very desirable quality for a high-speed passenger train. Chuo Shinkansen can accelerate at approximately 12 km/h/s while the Transrapid lies somewhere around 4 km/h/s.[23]

3. The effects of snow, ice and low temperatures on the maglev train technology Both the attracting (EMS) and repelling (EDS) system have weaknesses and strengths in the face of climate factors. For example, a layer of snow higher than the levitating distance could be highly resistant and obstructive to a running maglev train.[24] Ice stuck to the body of a maglev train could increase drag and make the vehicle more unstable. Factors such as these will be analyzed and discussed below. First of all we must however answer the question; “What differentiates a maglev train from a railway train?”. Since the focus of this report lies on deployment of the maglev technology in winter climate,

6

Maglev deployment in winter climate

the unique needs of a maglev train must be analyzed. Below is a table highlighting the main technological differences between the two types of trains (Table 1). If a piece of data is listed under one of the systems, it means that it is not of relevance for the other system.

Table 1. Differences between railway and maglev

Rail-bound trains

Connected to the ground

Propelled by wheels

Requires point contact for power supply

Tracks often rest on ballast

Maglev trains

Levitates 8-100 mm from the guideway

Propelled by magnetism

Carries strong magnets on board

Relies on batteries in case of failure

Relies heavily on feedback control and computers

Operational speeds over 350 km/h

3.1 Heavy snowfall - problems Let us start by taking a look at the effects of a layer of snow on the track or in the guideway. One of the most striking differences between the EDS and EMS system is the distance between the train and the tracks. As explained, the trains using EMS utilizes a gap of between 8 and 12 millimeters. For the EDS configuration, the levitational gap is 100 millimeters.[25] That clearance allows the train to hover over quite a lot of snow unbothered, while the volume of snow needed to reach a train using the EMS systems is much smaller. With this said, the electrodynamic suspension can not lift the rolling stock before reaching a velocity of around 150 km/h, and before that it relies on rubber wheels that are exposed to both slip and friction. This leaves the system as exposed to the elements as a conventional rail-vehicle. In contrary to this, the electromagnetically suspended trains can levitate even at standstill.[22]

With this said, the biggest problem with a layer of snow on the track is not the fact that the train needs to pierce it. The goal is to remove the snow before it reaches those levels. The most disruptive factor is the snow that whirls around the train after being disturbed by the flow-turbulence around the vehicle.[26] Just a few months after the Tokaido Shinkansen opened in 1964, there were problems with the train bogies due to snowfall. Whirling snow piled up on top of the bogies under the train, and when the snow fell down it caused gravel to scatter and damage parts of the vehicle.[27] [28]

Even a small layer of snow can lead to a cloud of atomized snow in the air from the turbulence of a passing train. One can imagine that these particles quickly pile up if the train runs for a long time. Many sources say that these clouds of whirling snow cause big problems.[26] [28] [29]

7

Maglev deployment in winter climate

This problem is more common when the snow is dry, as it more easily disperses under those conditions. These effects are mostly studied on conventional railway vehicles, but since bogies of maglev vehicles are similar these issues will be important to consider for them as well. Let's imagine a scenario where a maglev train runs at 500 km/h and a chunk of ice or packed snow come loose from the undercarriage of the train. The forces from this object could cause great damage to both the vehicle and the track. See Figure 6 below.

Figure 6. A hypothetical damaging ice/snow-chunk scenario.[41]

Other complications of snow accumulation on the bogies exist. For example, the snow and ice can limit the movement of the train and pose a danger to operation.[26] Elimination of pockets and areas where snow can pile up and cause damage need to be assessed. Other than the bogies, ventilation intakes and the structure in between the train vehicles are especially exposed to this build-up. It has also been proposed that if a layer of snow is formed in the U-shaped guideway that some maglev utilize, the surface of the snow in combination with the turbulence could cause erosion-deposition of the edges of the guideway.[30] This type of slow, over time damage must be predicted and prevented. Making sure that vital metal components do not corrode in unexpected ways is of course also of high priority, just like with conventional trains. The switches in the track can be sensitive to snowfall as well. Snow traveling with the wind horizontally can end up in the switches between the rail and the switches’ tongue. This can cause malfunction.[26] The topic of maglev track switches will be looked at further in chapter 3.2 as ice is one of the biggest issue for the rail-switches. 3.2 Heavy snowfall - solutions The Central Japanese Railway company explains that their new maglev train will run underground or in tunnels more than 80% of its route and that the outdoor areas will be equipped with hoods and/or sprinklers to protect from heavy snowfall and melt the snow that falls on the track. They say that this will prevent any impact from snowfall.[22]

As for the Linimo line in Nagoya, they provide the following information about snow- and rainfall; “The vehicle travels levitated by magnetism and does not use the adhesion between wheels and rails unlike railway vehicles. Therefore, it is not affected by weather conditions such as rainy weather and snow, and there is no slipping or skidding.” [10] In their Maglev deployment program report from 2001, the US department of transportation analyzes the Transrapid system. Their analysis concludes that snow and ice build-up is not an issue to the drive components as they are mounted on the underside of the guideway. Moreover, they claim that any

8

Maglev deployment in winter climate

snow that builds up on top of the track will blow off by wind or passing trains before a thick enough layer to be disruptive is accumulated.[32]

Figure 7. Sprinklers for removing snow on one of Japan's Shinkansen lines.[31]

With these cases presented, it must still be understood that most of today's maglev lines are not exposed to heavy snowfall or icing. The reason we discuss these issues is a lack of experience of operation in winter climate. Conventional trains that run in areas with proper winter climate do encounter issues from these elements. First of all, building tunnels is a clever solution that is applied for all kinds of trains. Japan's rail-bound Shinkansen use this solution for the tracks going north, to the Hokkaido region, where up to 80% of the tracks are covered by tunnels.[28] Another example is some parts of northern Sweden where hoods over the railway are utilized as protection from avalanches. One example is the area around Torneträsk in on of the northern-most parts of Sweden.[33]

The suggested solution of de-icing and removing snow with water sprinklers may not be a viable for countries where the cold climate is more persistent. De-icing with hot or cold water can lead to negative effects on very cold days, as some water that is left after the de-icing will refreeze under those conditions. For this reason, glycol mixtures with a freezing temperature well below zero can and have been used in low temperature areas instead of water.[26] Glycol agents do however need to be collected after usage as it may be toxic to the environment.[34]

If a sprinkler system is deemed to be the correct solution for a location, some temperature managing controls need to be put in place. As the temperature of the snow, concrete and other components around the track and train will vary, the liquid's temperature must also be controlled to maximize effect.[35]

As for the snow and ice that gathers on the bogies and undercarriage of the train, some solutions have been suggested. On the Japanese Shinkansen, heaters have successfully been used on the bogies to melt snow. Leading the train´s air conditioning waste heat to the bogies have also had some success.[36] A general design that utilizes rounded surfaces and low friction surfaces has been proven favorable.[26] Adding flaps or plates to improve aerodynamics and thereby let the snow pass the train more easily is

9

Maglev deployment in winter climate

another solution that has been successful.[37] Various coatings of antifreeze paint have also been suggested.[38]

Maglev tracks and guideways that are in operation today are ballastless. This means their foundation is some flat, solid body - usually concrete slabs. Ballastless tracks have been used for some conventional trains in cold regions, as the flat surface simplifies snow removal by water or air streams since the mediums are not dispersed like they would if the track was to laid on ballast. [28] This gives the general maglev track a natural advantage when it comes to snow removal. This type of tracks are generally accompanied by a higher initial investment, but lower maintenance costs. [39]

The Japanese Shinkansen tracks are equipped with some additional snow countermeasures. The ones that are assumed to be applicable to maglev tracks are presented below. [40]

● Snow trenches on the sides of the trackAfter gathering data about approximate snow-depths of a certain area, trenches of appropriate depth are constructed around the track for snow to accumulate in. See Figure 8.[40] The collected snow can more easily be tossed away or melted with heaters or sprinklers than if it was dispersed.[42] If the area is not exposed to extreme amounts of snow, the trenches can by themselves serve as a solution, as the snow might not reach the full height of the trench before it melts away. Proper drainage of the trenches are essential. Some similar system would most likely be applicable to a maglev system, as there is plenty of room for trenches at the bottom of the guideways, especially with the EDS systems.

Figure 8. Illustration of trenches used to accumulate snow[40]

● Heating and hot-water jetsSome railway switches on the Tohoku Shinkansen line utilize electric hot-air melting systems or hot water jets to ensure smooth operation of the rail forks.[40] More issues related to railway switches will be discussed in part 3.3.

● Avalanche and wind protection fencesThe Tohoku Shinkansen applies these fences mainly by the exit of tunnels, where snow may come tumbling from the adjacent hill. [40] See an example in Figure 9.

10

Maglev deployment in winter climate

Figure 9. Avalanche and snow-wind protection at Takamatsu tunnel in Japan.[43]

Another measure suggested by RTRI, the Railway Technical Research Institute, is to closely monitor the risk of snowfall and current snow depth to be able to allocate personnel efficiently. They have also suggested monitoring the quality of the snow to know how much potential damage it could do to a passing train.[29]

3.3 Ice - problems When it comes to ice, one of the biggest weaknesses in Swedish railway today are the railway switches. In June 2018, Sweden had already faced 7200 cases of switch-failure the same year.[44]

Between 15 and 20% of switch failures in Sweden are caused by snow or icing.[45]

Chunks of ice get stuck between the static rail and the switching rail, preventing the movement to be completed. The chunks often have to be removed manually, which is a time consuming and costly process.[46] The systems implemented in railway switches for maglev trains are often far more technically advanced that those of conventional trains. Yet, they use the same fundamental movement of some rail portion moving back-and-forth between two or more branches. The Shanghai Transrapid and the Nagoya Linimo EMS maglev trains use switches that bend a portion of the rail as long as 150m to get the desired curvature.[47] See an example of this in Figure 9.

Figure 9. Railway switch on the Linimo line in Nagoya, Japan.[43]

The Chuo Shinkansen utilizes a similar system that bends the whole U-shaped guideway. See Figure 10.[49]

11

Maglev deployment in winter climate

Figure 10. Railway switch on the Chuo Shinkansen [49]

In the same way as for conventional trains, ice could prevent the switching motions completion for both the EMS and EDS switches. At the extreme speeds some maglev trains can reach, a switch failure could have even more fatal consequences than for a rail-bound train. It is of high importance that a system is in place that lets the switches run smoothly even on days where icing could occur.

If we leave the switches and take a look at the general guideway structure, we see a heavy use of concrete for both the Chuo Shinkansen and the Shanghai transrapid. While these ballastless tracks come with some benefits as explained in chapter 3.2, they are also subject to frost wedging. Frost wedging is an issue for concrete structures like dams in cold regions. One solution to this issue is using concrete with higher air density to localize the effects of the damage from this phenomena. [50] Closely monitoring cracking and maintaining the condition of the track is essential as well.

Continuing to the train body, icing is especially problematic when a train is exposed to temperature transitions from above to below the 0oC limit. When that occurs, any water stuck to the various components of the body will freeze. One common situation when this can happen is the transition from inside a tunnel to an outside environment. Even though the outside is very cold, the temperature inside a tunnel might stay well over 0oC. This transition can lead to very quick temperature plummets. [26] Below, some negative effects of ice on the train body are discussed.

First of all, there is the issue of increased drag and weight. This is also a problem for rail-bound trains, but since the drag force is mathematically dependent on the velocity squared it is even more important to focus on aerodynamic aspects in high-speed maglev trains for efficiency reasons. If the train is to be kept efficient at high speeds it is important that the body is kept aerodynamic and free of turbulence. Another side-effect of ice stuck to the body is increased weight, which leads to less efficient acceleration and deceleration. Ice around dampers and springs could pose maneuverability issues as well. It is clear that the Chuo Shinkansen has gone through extensive development to optimise aerodynamics, see Figure 11 below.

Not only does turbulence increase drag, it can also create extra aeroacoustic noise which can be of great discomfort to the passengers and create damaging vibrations in the vehicle. These vibrations become much greater at higher running speeds and are extra prevalent in tunnels. [51]

12

Maglev deployment in winter climate

Experiments conducted on the Transrapid trains concluded that the main sources of aeroacoustic noise came from flow-interactions with the levitation frame and various ventilation inlets.[52] This side-effect of turbulence is another reason to keep the vehicle free of ice and snow. Studies done on the Shinkansen trains in Japan have concluded that 50% of the total noise from trains travelling at 300 km/h or faster is aeroacoustic noise created by the bogies and other components beneath the vehicle.[51] Layers of ice will add to this effect quickly, and it serves as further evidence to the importance of de-icing.

Figure 11. The L0-series Chuo Shinkansen train.[53]

3.3 Ice - solutions Many of the solutions to snowfall naturally applies to icing as well, so below the focus will lie on the solutions unique to icing. To ensure ice free switches and trains, some systems must be put in place to either melt or prevent the formation of ice. The most common systems for conventional trains are Hot air, hot or cold water, or heated glycol. Melting ice with hot air uses a lot of energy and takes time. Water has the risk of, as mentioned earlier, refreezing. Glycol does not freeze but needs to be taken care of after being sprayed onto the train or rail-switch. There is little difference between conventional- and maglev trains when it comes to de-icing.[26] These solutions could most likely be successfully applied to maglev trains as well, but must be assessed on a case-to-case basis. One important thing to keep in mind is that melting ice in one place will create a flow of water that ends up somewhere else. If the melted water is not properly lead away from the train, it might cause icing in even more undesirable places.[26] As for the railway switches, one solution is to build hoods over the portion of the track where it branches. This has successfully been applied at 10 spots in Hokkaido in Japan. see Figure 12 below. In Sweden, approximately 50% of all railway switches are equipped with heating systems for de-icing.[59]

13

Maglev deployment in winter climate

Figure 12. Hood that protects railway switches from snow and rain that can lead to icing.[28]

3.5 Low temperatures - problems The first crucial difficulty in a low temperature environment is the management of computer systems. While computers and control systems are increasing in amount and importance for most vehicle technologies, maglev trains are possibly on the frontlines. Booting issues and shutdowns can happen when a computer is exposed to low temperatures. Condensation inside the system can cause short-circuits, and cold hard-drives can have a difficult time booting up. It is important to put systems in place that assures proper working conditions for the computers. Dry and well-tempered air being the most important. [26] [54]

Materials generally change their properties when exposed to the temperature of a very cold day in Sweden. These changes are often unpleasant, since metals can become more brittle, rubber less flexible, and lubricants less viscous.[26] These are only three examples, but whatever systems are put in place that can be exposed to these negative effects some solution has to be put in place. Maglev trains use bogies just like most rail-bound trains. These are usually equipped with dampers[57] or air springs.[10] Cold air changes the damping constant for them since the density of the air changes. It is important that the feedback control can handle situations with changed damping conditions. Most of today's Maglev trains utilize batteries for backup storage, in the case of a power outage or a similar situation.[10] Lithium-ion batteries, which are commonly utilized for electrical vehicles today, are known to consume more energy when they are cold.[55] Since the batteries on board of the maglev trains should at least carry the capacity to reach the closest evacuation zone, the need of additional battery capacity might be necessary in low temperature environments.[56]

3.6 Low temperatures - solutions When it comes to dampers, it is important to make sure that the damper oil and the sealing is suitable for low temperatures.[26]

Keeping closer measurements of battery capacity might be necessary to manage the power output in the case of an emergency.

14

Maglev deployment in winter climate

One of the most important things is putting a system in place that monitors the temperature. Historical data of temperature levels at different times of year will also be helpful. The current temperature and its rate of change can be used to know what snow levels to expect, the quality of the snow, if there is a risk of icing, and so on. That data can furthermore be used to calibrate heating systems, water sprinklers, train performance (for example dampers, and similar systems.

4. Conclusions

There are some added factors to consider for someone who wants to build maglev systems in colder regions. Many or most elements are however the same as those for conventional railway and it is therefore suggested to study them well in addition to the factors presented in this report.

The most notable unique challenges for maglev in winter climate come with the added forces of high speed. Turbulence at high speeds caused by icing on the vehicle lead to aeroacoustic noise and vibrations. Ice or snow falling off the vehicle at high velocities can cause harm to both the vehicle and guideway as the forces become very large.

Thanks to its levitating nature, maglev is resistant to small layers of snow in the guideway and on the track. Atomized snow is however problematic, as it causes buildup of snow on the bogies which at high density creates similar issues as ice. The buildups can also restrict the movement of the bogies and lower their average temperature. Lower temperatures change material properties and can for example change damping constants.

There are many clever solutions out there already. Japan is the country leading the maglev development at this point in time. Their main solutions can be broken down to a combination of leading the guideways underground, protecting them with hoods, using water sprinklers to remove snow and elevating the guideways and rails to minimize snow buildup.

5. Further research

Depending on the future development and viability of SpaceX’s Hyperloop technology, it might be of interest to look into how the factors mentioned in the report are altered when the whole system it put into a vacuum tunnel. For example, the low heat transfer properties of the vacuum surroundings might pose challenges or opportunities in the cold. The vacuum tunnel might need extra reinforcements to withstand the battle with the elements.

It would be of economic value to investigate how a maglev train in for example Sweden, Norway, or Finland compares economically to keeping the current system and to flying.

15

Maglev deployment in winter climate

Bonus chapter: Is the maglev technology environmentally sustainable? First and foremost, high-speed rail in general can be a great alternative to flying in terms of both energy consumption and time. One report from the Central Japan Railway Company suggests that the superconductive maglev line will consume a third of the energy than an airplane would.[61]

Efficient trains also increases the incentive of not using a car. it has been suggested that the total travel time from Tokyo city centre to Osaka city centre when the Chuo Shinkansen is finished will be 84 minutes while today´s total time by plane is 156 minutes.[61] This has to do with the fact that trains can take the passengers straight to a city centre, as opposed to an aircraft that require an airport outside of the city. This time-efficiency is however mitigated with increasing distance, as the take-off and landing procedures of the aircraft become a smaller percentage of the journey. It must also be mentioned that the infrastructure project of building a rail system through a country is both costly and energy consuming. The total cost of the chuo Shinkansen line is approximately 9 Trillion yen - that is around USD 84 billion as of 2011.[22] When it comes to energy consumption, the Chuo Shinkansen is less efficient than a railway equivalent. A railway Shinkansen train consumes approximately 29 Wh/seat/km while the Chuo Shinkansen is estimated to consume somewhere between 90 and 100 Wh/seat/km.[62]

The Central Japan Railway Company is addressing this issue by conducting research on how to make it more efficient. For example, some progress has been made towards superconductors that do not require as low temperatures as before.[22] Noise is a big concern for trains travelling through urban areas. Noise can lead to stress and other health conditions in humans as well as damage to the surrounding physical environment.[63] Maglev have less sources of noise compared to a railway vehicle (see Figure 13), but the high speeds leads to aeroacoustic noise as explained in chapter 3.3. The Central Japan Railway Company has solved this with sound-barriers on the sections where the vehicle runs outdoors. As most of the guideway lies inside tunnels, noise will not be an issue for the surroundings there.[22]

Figure 13. Sources of noise in maglev and railway vehicles.[22]

When it comes to cold climate issues, extra efficiency in heating systems, water sprinklers, and similar systems might be necessary. The difference from conventional railway will most likely not be

16

Maglev deployment in winter climate

extreme. As explained in chapter 3.3, melting ice and snow with heat and/or water generally requires a lot of energy, so it should be worth looking into solutions tailored to a maglev guideway. Maglev systems are generally more battery-reliant than conventional trains. Lithium Ion batteries are a cause of controversy as one of the contents, Cobalt, is often mined under very poor working conditions. Some of the metals in Lithium Ion batteries might be damaging to the nature as well. Since the vehicles will be used for long times, and the batteries are only utilized in emergencies, this should however not be considered a problem. References [1] Andersson, E., Berg, M., Nelldal, B.-L., & Stichel, S. (2020). Varför behövs Nya Stambanor i Sverige? Stockholm: KTH Royal Institute of Technology. Retrieved from: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-267214 [2] Fröidh, O.(2013) Godstrafik på järnväg – åtgärder för ökad kapacitet på lång sikt, KTH Royal Institute of Technology, Architecture and Civil engineering. Retrieved from: https://www.kth.se/polopoly_fs/1.442275.1550156530!/Menu/general/column-content/attachment/13_003RR_rapport.pdf [3] Andersson E, Berg M, Stichel S and Casanueva C: Future perspectives on rail traffic, Chapter 11 in textbook Rail Systems and Rail Vehicles, Part 1: Rail Systems, ISBN 978-91-7729-730-7, KTH Railway Group, Stockholm, 2018. [4] Hyperloop official website, Hyperloop information page. (2020) Information retrieved (2020-04-14) from: https://www.spacex.com/hyperloopalpha [5] Google patents, Monorail with wheel-less vehicles which are guided on rails by means of magnetic fields iron suspended along. (1934) Hermann Kemper Dipling. Retrieved from: https://patents.google.com/patent/DE643316C/en [6] BBC news, (1999) The magnetic attraction of trains, Retrieved from: http://news.bbc.co.uk/2/hi/science/nature/488394.stm [7] Doppelmayr official website, Birmingham International Airport Air-Rail Link, Information retrieved (2020-04-14) from: https://www.dcc.at/references/birmingham-international-airport-air-rail-link/ [8] Maglev.net, (2018) The world's first maglev lines that no longer operate, retrieved (2020-04-14) from: https://www.maglev.net/worlds-first-maglev-lines-no-longer-operate [9] Shanghai Maglev Transportation Development Co.,Ltd official website, (2005) Chronicle of events. retrieved (2020-04-14) from:http://www.smtdc.com/en/gycf2.html [10] Linimo official website, リニモとは？(What is Linimo?) (2018). Information retrieved (2020-04-14) from: http://www.linimo.jp/linimo/2018021414360822.html [11] Railway-technology.com, (2020) Chuo Shinkansen Maglev Line, retrieved (2020-04-14) from: https://www.railway-technology.com/projects/chuo-Shinkansen-maglev-line/ [12] Paradot, N. Masson. E, Poisson, F., Grégoire. R, Guilloteau. E, Touil, H. Sagaut. P, (2008/01/01) Aero-acoustic Methods for High-speed Train Noise Prediction, WCRR (World Congress on Railway Research), Seoul, Korea. Retrieved (2020-04-14) from: https://www.researchgate.net/publication/256082935_Aero-acoustic_Methods_for_High-speed_Train_Noise_Prediction

17

Maglev deployment in winter climate

[13] Trafikverket.se, Varför konventionell järnväg och inte magnettåg? (Why conventional railway and not maglev?) (2020-02-25), Retrieved (2020-04-14) from: https://www.trafikverket.se/nara-dig/projekt-i-flera-lan/Ostlanken/fragor-och-svar-om-ostlanken/ [14] Livingston, J.D., (2011) Rising Force 9780674055353, Harvard University Press, Retreived (2020-04-14) from: https://books.google.se/books?id=5wbi2TWBX1QC [15] Yadav, A. (2016) Effect of Temperature on Electric Current, Magnets and Electromagnet, Retrieved (2020-04-14) from: https://www.longdom.org/open-access/effect-of-temperature-on-electric-current-magnets-and-electromagnet-0976-4860-1000167.pdf [16] Uno, M. (2016) Chuo Shinkansen project using superconducting maglev system, Retrieved (2020-04-14) from: http://www.ejrcf.or.jp/jrtr/jrtr68/pdf/14-25.pdf [17] Boldea, I., (2017) Linear Electric Machines, Drives, and MAGLEVs Handbook, CRC Press, 9781439845158, Retrieved (2020-04-14) from: https://books.google.se/books?id=bHDRBQAAQBAJ [18] Shanghai Maglev Transportation Development Co.,Ltd official website, (2005) Principle of Magnetic Levitation. Retrieved (2020-04-14) from: http://www.smtdc.com/en/gycf3.html [19] SCmaglev official website, (2020) About SCmaglev, Retrieved (2020-04-14) from: https://scmaglev.jr-central-global.com/about/ [20] Supraconductivite.fr, (2020) MAGLEV The flying train, Retrieved (2020-04-14) from: http://www.supraconductivite.fr/en/index.php?p=applications-trains-maglev-more [21] 松 田 和 久(Matsuda, K), (1993) リニ ア 新 幹 線 の 制 御 シ ス テ ム (Linear Shinkansen control system), Retrieved (2020-04-14) from: https://www.jstage.jst.go.jp/article/sicejl1962/32/7/32_7_573/_pdf [22] SCmaglev official website, (2020) Frequently asked questions, Retrieved (2020-04-14) from: https://scmaglev.jr-central-global.com/faq/ [23] ShirakuniI N. (2010) Present and future state of high speed railways, Central Japan Railway Company, Retrieved (2020-04-15) from: https://www.jstage.jst.go.jp/article/jsmemovic/2010/0/2010__2K11-1_/_pdf/-char/en [24] Izumi, I., Nakamura, T., Sack, R.L. (1997) Snow Engineering: Recent Advances: Proceedings of the third international conference, Sendai, Japan, 26-31 May 1996, Taylor & Francis 9789054108658. Retrieved (2020-04-15) from: https://books.google.se/books?id=l4IvF1CVDtwC [25] Jrailpass.com, The Japanese Maglev: World’s fastest bullet train, Retrieved (2020-04-15) from: https://www.jrailpass.com/blog/maglev-bullet-train [26] Kloow, L. (2011) High-speed train operation in winter climate, KTH Railway Group Publication 1106, https://www.railwaygroup.kth.se/ [27] 大坂 直樹 (Osaka, N), 東海道新幹線が｢大雪｣でも運休しない舞台裏 (The reason why the Tokaido Shinkansen doesn’t even stop during heavy snow conditions), Retrieved (2020-04-15) from: https://toyokeizai.net/articles/-/104644?page=2 [28] weathernews.jp, 北海道新幹線開業！ 世界一の雪対策 (Hokkaido Shinkansen opening! The best snow measures in the world), Retrieved (2020-04-15) from: http://weathernews.jp/soramagazine/201604/01/

18

Maglev deployment in winter climate

[29] Kamata, Y. Nemoto, M. Takahashi, D. Kurihara, Y. Shishido, M. Iikura, S. (2012) 新幹線台車への着雪量予測のための雪の舞い上がり試験 (Snow flying up experiment for forecasting snow accretion to Shinkansen bogie), Retrieved (2020-04-15) from: https://www.jstage.jst.go.jp/article/jcsir/2012/0/2012_110/_pdf/-char/en [30] Izumi, I., Nakamura, T., Sack, R.L. (1997) Snow Engineering: Recent Advances: Proceedings of the third international conference, Sendai, Japan, 26-31 May 1996, Taylor & Francis 9789054108658. Retrieved (2020-04-15) from: https://books.google.se/books?id=l4IvF1CVDtwC (page 105) [31] 新幹線とスプリンクラー https://www.es-waternet.co.jp/case/detail?id=137 [32] United States. Federal railway Administration, (2001) Maglev Deployment Program, Programmatic EIS: Environmental Impact Statement, Retrieved (2020-04-15) from: https://books.google.se/books?id=Qbc2AQAAMAAJ (page C-40) [33] Kiruna kommun, (2014) Fördjupad översiktsplan för torneträskområdet, Retrieved (2020-04-15) from: https://www.kiruna.se/contentassets/bfb3b99aaad449539b6de985fe6f5956/fop-riksgransen-tornetrask2014.pdf [34] United States Environmental Protection Agency, (2000) Ethylene Glycol, Retrieved (2020-04-15) from: https://www.epa.gov/sites/production/files/2016-09/documents/ethylene-glycol.pdf [35] Noguchi, M. Kobayashi, H. Kikuchi, T. Iikura, S. Kawashima, K. Iyobe, T. Fujii, T. (2012) 東北新幹線八戸・新青森間における雪害対策の研究, (Snow control measures on the Tohoku Shinkansen line between Hachinohe and Shin-Aomori). Retrieved (2020-04-15) from: https://www.jstage.jst.go.jp/article/jcsir/2012/0/2012_190/_pdf/-char/en [36] 我妻 徹, 堀川 重成, 藤野 謙司, 橋本 克史, (2010) JR EAST Technical Review No.31-SPRING.2010, 雪対策, (Snow measures), Retrieved (2020-04-15) from: https://www.jreast.co.jp/development/tech/pdf_31/Tech-31-31-34.pdf [37] Kitayama, S. (CentralJapanRailwayCompany), Sumita, K. (CentralJapanRailwayCompany), Shigeyama, M. (Hitachi，Ltd.), Morita, K. (Hitachi，Ltd.), (2005) 台車周りの空力特性改善に関する研究 (Research Qn aerodynamic characteristic improvementaround bogie), Retrieved (2020-04-15) from: https://www.jreast.co.jp/development/tech/pdf_31/Tech-31-31-34.pdf [38] 大石不二夫, 村瀬平八, 村 田仁司,木暮英雄, 糟谷 滋 (1990)新しい雪氷固着防止コーティングの 耐久性 (Durability of new snow-and ice protective coating), Retrieved (2020-04-15) from: https://www.jstage.jst.go.jp/article/mls1989/3/1/3_1_48/_pdf/-char/en [39] https://www.trackopedia.info , Ballastless track, Retrieved (2020-04-15) from: https://www.trackopedia.info/encyclopedia/infrastructure/superstructure/ballastless-track/ [40] 田村曄, 塩田 雄三, (1982) 東北新幹線における雪対策 (Anti-snow measures on the Tohoku Shinkansen), Retrieved (2020-04-15) from: https://www.jstage.jst.go.jp/article/seppyo1941/44/3/44_3_153/_pdf [41] Axel THORSTRAND, own illustration [42] 乗りものニュース (Vehicle news/Traffic news), 北陸新幹線、雪に強い、強すぎる！　在来線と何が違うのか (Hokuriku Shinkansen, strong against snow, too strong! What is different from conventional lines). Retrieved (2020-04-15) from: https://trafficnews.jp/post/79649/2 [43] Newrode Photography Diary, 高松トンネル (Takamatsu tunnel), Retrieved (2020-04-15) from: http://new35313227.blog.fc2.com/blog-entry-31.html [44] Jönsson, O. Lundström, K. (2018) Dramatisk ökning av fel på landets järnvägsväxlar (Dramatic increase in errors on the country's railway switches), Retrieved (2020-04-15) from: https://www.svt.se/nyheter/inrikes/dramatisk-okning-av-fel-pa-landets-jarnvagsvaxlar

19

Maglev deployment in winter climate

[45] HUA, H. Tosovic, N. (2017) Förseningsminuter i samband med spårväxel-fel på den svenska järnvägen (Delays in relation to railway switch failures on swedish railways), Retrieved (2020-04-15) from: http://lup.lub.lu.se/luur/download?func=downloadFile&recordOId=8913049&fileOId=8961933 [46] Hallandstrafiken, Växelfel på vintern (railway switch failure during the winter), Retrieved (2020-04-15) from: https://www.hallandstrafiken.se/vaxelfel [47] Monorails.org, (2020) Transrapid - Guideway & Switching, Retrieved (2020-04-15) from: http://www.monorails.org/tMspages/TPTRguid.html [48] Youtube.com, video of switching Linimo rail, Linimo Maglev Switch リニモ, Retrieved (2020-04-15) from: https://www.youtube.com/watch?v=WZ_PdCgz7ik [49] Yamanashi Prefectural Maglev Exhibition Center, リニアの仕組み (Linear maglev structure), Retrieved (2020-04-15) from: https://www.linear-museum.pref.yamanashi.jp/about/structure.html [50] Eriksson, D. Malm, R (2018) Simulering av frostsprängning i betong (Simulation of frost wedging in concrete). Retrieved (2020-04-15) from: https://byggteknikforlaget.se/simulering-av-frostsprangning-i-betong/ [51] Nagakura, K. (2018) Recent studies on aerodynamic characteristics of railway vehicles, Retrieved (2020-04-15) from: https://www.jstage.jst.go.jp/article/rtriqr/59/2/59_81/_pdf/-char/en [52] Volpe, J, A. National Transportation System Center, Cambridge, MA 02142, July 2002. Noise Characteristics of the Transrapid TR08 Maglev System, Chapter 1.5 Test Facility, US Department of Transportation, Research and Special Programs 43 Administration,. Retrieved 2020-04-15 [53] SCmaglev official website, picture gallery. Retrieved 2020-04-15: https://scmaglev.jr-central-global.com/gallery/ [54] Ipoint Tech, (2013) Cold Weather Effects on Computers, Retrieved 2020-04-15 from: https://ipoint-tech.com/avoid-frozen-computer/ [55] Tesla official website, Tips för vinterkörning (Tips for winter driving), Retrieved 2020-04-15 from: https://www.tesla.com/sv_SE/support/winter-driving-tips [56] United States. Federal railway Administration, (2001) Maglev Deployment Program, Programmatic EIS: Environmental Impact Statement, Retrieved (2020-04-15) from: https://books.google.se/books?id=Qbc2AQAAMAAJ (page C-36) [57] Gieras, J. F. Zbigniew J. P. Bronislaw, T. (2018) Linear Synchronous Motors: Transportation and Automation Systems, Second Edition, , Retrieved (2020-04-15) from: https://books.google.se/books?id=LX9XDwAAQBAJ&dq=transrapid+boggie&hl=sv&source=gbs_navlinks_s (Page 329) [58] Zirguezi, wikipedia user, 14 January 2018, A diagram illustrating a magnetic levitation train. Retrieved (2020-04-15) from: https://commons.wikimedia.org/wiki/File:JR_Maglev-Lev.svg [59] Trafikverket, 2018. Snöröjning av linjen (Snow removal on the railway). Retreived 2020-05-02 from: https://www.trafikverket.se/resa-och-trafik/underhall-av-vag-och-jarnvag/Sa-skoter-vi-jarnvagar/Snorojning-av-jarnvagen/Snorojning-i-linjen-/ [60] Linimo official website, 2020. photo gallery. Retreived 2020-05-03 from: http://www.linimo.jp/information/2018020711520195.html [61] Shirakuni, N. Central Japan Railway Company, 2010. Present and future state of high speed railways. Retrieved 2020-05-03 from: https://www.jstage.jst.go.jp/article/jsmemovic/2010/0/2010__2K11-1_/_pdf/-char/en

20

Maglev deployment in winter climate

[62] 一夫澤田(Kazuo, S), 2002 鉄道を他輸送機関と比較する (Comparing trains to other transportation) Retrieved 2020-05-03 from: https://bunken.rtri.or.jp/PDF/cdroms1/0009/2002/20000902010401.pdf [63] Karolinska Institutet, 2019. Oönskat ljud negativt för hälsan. Retraived 2020-05-03 from: https://ki.se/forskning/oonskat-ljud-negativt-for-halsan

21

www.kth.se