Transportation Deployment Casebook/2018/Maglev train system (1922-2016)

The growth of population and expansion of the resident living zones for each city heavily rely on a highly developed transportation systems in terms of road networks, rail systems and air service. An awareness of general publics that a good transportation system or transit pattern can play a significant role in ensuring a high efficiency of individuals works and lives has been realized. Progress of science and technology not only contributes to create new transport patterns to improve efficiency of travelling, feeding the travel demands from increasing population, but also alarms people having to considering sustainability regarding society, environment, general health and economy. Therefore, a new technological transport production maglev train has been produced based on the consideration.

Birth of maglev train

The concept of maglev train was proposed by a German engineer Hermann Kemper and patented in 1922. The magnetic levitation technique then experienced an intensive development through the past few decades and was mature in 1970s-1980s. After a period of trails and tests in 1990s, the final practical public service has been successfully accomplished in Shanghai in 2003. Maglev train applies magnets to accomplish suspension, propulsion and guidance. To compare the conventional trains, the maglev system successfully substitutes wheels and accomplishes to suspend the train, keeping maximum 10 mm air gap between bottom of the train and guidance by electromagnetic force. No connection between train and rail significantly avoids a resistance caused by the rolling friction when wheels running on the rails, this characteristic helps maglev system achieve many incomparable advantages in terms of speed, maintenance, safety and environmental friendly.

Features

Before the birth of maglev train, existing rail systems are mainly used to serve in the middle and long-distance trips. Gradually, the massive consumption of fuel, negative impacts on environment, noise and high cost for maintenance trigger people attempting to create a new transport mode or improve the traditional train systems. The common electromagnetic force characterized by its easily producing and no fuel consumption reasonably became a new energy resources applied for train moving. Comparing the existing rail system, maglev train has lower vibration and noise due to suspension on the guidance, no mechanic connection can reduce the noise from general 75-80 dB to 60-65 dB. Superconductivity maglev train can reach a velocity up to 500–600 km/hr, which is superior to take airplane in trips of distance between 1000 to 1500 km. No resistance also devotes to reduce power consumption, the most advanced maglev technique can support 30% reduction of power than high-speed rail. Furthermore, safety is a remarkable characteristic of maglev system, the design of the train and guideway can accomplish no possibility of derailment. No abrasion also focuses on decreasing the cost on maintaining and repairing the rails and wheels. Electromagnetic force as propulsion directly reduce consumption of non-renewable energy resources, mitigating emission of green-house gases.

Technology Characteristic

The essential mechanisms applied on the maglev train for suspension, guidance and propulsion are magnetic repulsion and attraction, electromagnetic induction and Lorentz force.

Levitation

The levitation technologies can be mainly divided into Electromagnetic and suspension (EMS) and electrodynamic suspension (EDS). EMS contributes to utilize magnetic attraction force to achieve suspension of the train. A pair of electromagnets are fixed on the guideway and other pairs with different magnetic pole are fixed on the bottom of the train. The method is relatively unstable due to the magnetic circuit. Through alternating current to accomplish the change of the current so that the electromagnetic field will be changed. The difficulty of the technique is to control the electromagnetic field to keep an appropriate air gap. EMS also contains levitation and guidance integrated and levitation guidance separated. The former is suitable for low speed operation and low cost because there are fewer electromagnets and controllers in the application, but the electromagnets are near the guidance so that the interfere between the train and guidance can be produced. The second method can be applied for high-speed service with higher costs because the separated levitation and guideway can reduce interfere between them.

EDS commonly applies magnetic repulsion to suspend the train(EDS) . The common materials used are permanent magnets like superconductivity magnets and electromagnets. The design is to attach magnets on the bottom of the train and the top of the guideway with same magnet pole. The produced repulsion can lift the objects without controlling the current to keep the air gap. Therefore, the design can be expected to transport heavier load or freights with a high-speed. Permanent magnet type is simple because electric power would not be used in the design. The superconductivity magnet is complicated, which relies on high-powered current with high temperature.

Propulsion

Maglev train relies on electromagnetic force to produce power to drive the train move forward. The design of the propulsion force is to change traditional rotary motor to linear motor (Lee.H, Kim & Lee.J, 2006). The linear induction motor can be imagined by through a variant magnetic to across through the coils which attached under the bottom of the train, so that the electromagnetic current will be produced, by which the current flowing within the coils in a magnetic field will produce Lorenz force which is perpendicular to the current flow to force the train move. Linear synchronous motor is another design to provide propulsion for maglev system. The train will be fixed a permanent magnet in the front part of the train. The local magnetic field and armature currents on the guideway will interact and produce Lorenz force to drive the train move.

Guidance

The guidance is to fix the suspended train to be stable and prevent the occurrence of lateral displacement and derailment. The mechanism mainly is used is also the magnetic repulsion. The magnets will be attached on the both sides of the train and both sides of the guideway with the same magnetic pole. The forces from both side to the center line of the train will ensure no lateral movement occur when the train is turning, or lateral wind may force the train deviate off the gateway.

Market development

The market development of the maglev train was bumpy due to the undeveloped and immature technology and high construction cost. The initial market niches of the maglev train can be derived from the awareness from the general public to develop sustainable energy resources, aiming to reduce consumption of fossil fuel and emission of greenhouse gases. Inner-city maglev system which served in short-distance connections can effectivelt reduce noise pollution and traffic congestions. The electromagnetic energy as an alternative candidate attracts more and more focuses on it. However, the present technology may not accomplish the high-speed maglev system and generalized to transportation application. Therefore, the middle or low-speed maglev train opened a new market path. After 1922 the concept of the maglev train was proposed, the technology limitation still constrained the development in the next 30 years. Until in the 1969, the first maglev train model was established by the German company Krauss-Maffei with 80 kg weight, 1m length and 4mm suspension height. In 1970 the German government commenced to develop the high-speed maglev train with a simple structure. By 1984, a maglev line was established in service between Birmingham airport and Birmingham train station in U.K. In 1991, the high-speed maglev train would be considered to reach the application model. Later, China and German through cooperation plan accomplished the first commercial and general uses inner-city maglev train (from Shanghai Pudong Airport to Longyang Road subway station) in the world. Japan focused on developing low-speed maglev transport service, which developed and applied the bogie embedded modular structure for maglev train. Therefore, Japan is the first country to apply an unpiloted low-speed maglev train line for serving 2005 Aichi EXPO, owning total distance of 9 km with the highest speed up to 100 km/hr. To address traffic problems in major cities, Korea started to develop low-speed maglev train in 2004. In 2007, the first maglev line which would be served for Incheon International Airport has been completely constructed. The market niche of the maglev train can be also understood that the most advantages of the train are levitation and renewable energy resource. Canceling the friction between train and guideway can effectively accomplish a much higher speed, in another word, this is an achievement which makes the vehicle fly in a very low height. Magnetic force can be a new energy in the future application to reduce consumption of fossil fuel. The incomparable advantage can create new market with respect to development of production for reduction or isolation of electric and magnetic field.

Policy for Maglev development

The policy seemed to pay more attention on environment impacts in terms of noise, electric and magnetic field. The noise pollution can be considered to include the structural/mechanical noise like mechanical brakes and panel vibrations, aerodynamic noise caused by wakes, wind shear or boundary layer separation, as well as noise resulted from turbulent boundary layer. The policy from Federal Transit Administration (FTA) which is specific for Japanese Urban Maglev System (CHSST) clarified the requirements for the noise that Noise level should be less than 67dBA inside the vehicle and noise level less than 70 dBA outside of the vehicle. The policy for electric field is a new innovation specific for maglev system, which referred to the electrical field limits AGGIH 1999 Standard. The standard illustrates that maximum allowable AC electric field that the general public can be exposed is 5 kV/m and 1 kV/m for the people who wear medical electronic protectors. A person who works on the equipment for eight hours per day can receive AC electric field intensity is 25V/m for frequency by 100 Hz and 2.5*10^6/fv/m from 100 Hz to 4 kHz. The limited AC electric field for eight hours per day working exposure is 2.5*10^6. Magnetic field limited also be standardized on the basis of the AGGIH 1999 Standards. The maximum limitation should ne considered to suitable for the weakest individual group such as the people who are installed the cardiac pacemakers or other implanted electronic devices because the local magnetic field on the vehicle would be 10 times the earth’s magnetic field. The allowable limitation of the continuous static magnet field is 5 Gauss for the medical electronic wearers and limitation of 1 Gauss for a worker who always works on the equipment for eight hours per day with cardiac pacemakers. Less than 1 Gauss have to be satisfied under the time variant AC magnetic field for frequencies from 1 Hz to 300 Hz.

The initial policy which focused on the noise, electrical and magnetic field from the FTA was based on the U.S. industry, providing the important guidelines for both passengers and workers who would be exposed in a long-term electric and magnetic field. As the development of the CHSST, additional concerns from the general public were needed to be clarified and regulated, by which more detailed and specific policies have been sanctioned. In the developing stage, the measurements of the electromagnetic interference were greater than the specification, the new regulation demonstrated that the electromagnetic interference measurements should be made inside the CHSS. Simultaneously, electric field measurements should be made repetitively for the sub radio frequency range.

Issues and strategies

Establishing and applying the maglev train line still does trigger massive arguments as general public gradually cognizing such new transportation system. Firstly, the technology might be not enough to support the operation of the maglev system. For example, the first trail operation maglev line which was established in 1984 with total distance of 600m from Birmingham airport to Birmingham train station had been abolished after a few years of operation due to the instability responded by users. Therefore, in order to address the problem, the policy from the British government did not decided to modify the maglev train but change the maglev line by a monorail train. Furthermore, the high-speed maglev train line is too different to develop and generalize for commercial use. The technology may involve developing super high temperature superconductivity guideway, which is still constrained by heat dissipation and electric power output. Thus, the strategy of each country who were studying and developing the maglev system casually reached a consensus, shifting their contributions on low-speed and short-distance trips. Therefore, Japan, Korea and China successively developed and grasped the technology. Secondly, the magnetic field impact has been a highlight to attract argues. The high-speed maglev train requiring stronger maglev field may be much greater than the normal allowable condition, which is also a reason that maglev system can bot be generally applied. Although the Low-speed mode is under the allowable condition, 10 times greater than the earth magnetic field has already been a crucial reason leading to massive rejections from public. Thirdly, the high budget for establishing the maglev system is an indispensable issue. For instance, there were approximately ￥100 billion for the 30 km construction of Shanghai Pudong maglev line and for $1.2 billion for expansion. In spite of different terrain may lead to different cost for construction, in an average condition, it is estimated that 1 cm construction of maglev system will expense ￥8000. The high cost will bring a high price of price. The price for Shanghai Pudong maglev line was up to highest ￥100 per person when the line was just opened for the public. Although the Shanghai government grant policy to reduce the price to ￥50 per person, a great amount of people supposed that they cannot accept. Moreover, the system exists potential risks resulted from weather condition changes and power cut. Therefore, the status of the maglev train in the world is tough to generalize and commercialize. Although many countries like China, Japan, Germany, U.S. and Korea are still contributing to develop the technology, government also will encourage to study renewable energy resource, deficiency of technology, high cost and, magnetic field may be the significant constraints to impede the application of maglev train.

Quantitative analysis

Due to the deficiency of technology, high cost and strong magnetic field, maglev system is not developed maturely and generally applied. Highlighted arguments from general public and specific workers and specialists triggered discussion whether the maglev should be constructed, which led to many cancels of planned or existing maglev project in many countries like Germany, U.K. and China. In facts, there are not too much track distances and many passengers of maglev train in the world and the only existing maglev lines mostly are served in a short-distance and low-speed as a convenience to connect cities’ airports and train stations. Therefore, track distances and passengers are less and not reliable data to express the development level of maglev system. Taking consideration of the aim of the maglev train which is to avoid rolling resistance to accomplish an extreme high speed, the data contributing to the velocity of the train development would be used. Japanese is one of the most important and the earliest country to develop the maglev train. The speed of the train already has increased from 90 km/hr to 603 km/hr in 2016.

Japan started the development of maglev is in 1969, Miyazaki test accomplished the high speed reaching to 517 km/hr in 1979. Unfortunately, the train was destroyed by an accident which may revealed the unreliability. Development of HSST commenced in 1974 in Tsukuba, which focused on the relative low-speed domain. HSST-03 became popular at that time with speed 30 km/hr for Tsukuba World Exposition. In 1987, MLU001 recorded the fastest speed up to 401 km/hr.

Methodology

The method to study the status of Japan maglev train development level with respect to speed can be referred to Garrison and Levinson (2014). On the basis of the speed data from the birth date to the present date through the life cycle of the system, the predicted possible speed can be estimated.

The formula: S(t) = K/[1+EXP(-b*(t-t0))] can help to predict the speed development tendency in the future. S(t) is measured status, t is time, t0 is inflection time, K is saturation status level (here is specific for speed) and b is a coefficient.

K value can be decided by estimating from the largest value of speed, which is 603 km/hr, increasing by 1 km/hr. Through observing the RSQ value the K value can be decided which matches the R value which are mostly near 1. The b is the slope of the dataset which can be calculated according to the K value and time.

Parameters for the S-Curve formula

Variable	Description	Value
t	Time
t0	Inflection time	1976.1
K	Saturation status level	606
b	Coefficient	0.117754738
RSQ	R-squared	0.81130

The original & estimated data

S curve analysis for Japan maglev speed

Discussion

The S curve indicates that the development of speed of Japan maglev train seems to be saturated, which may imply a maximum limitation that the speed of the train can be enhanced. There are obvious differences between realistic speed and predicted speed. The realistic speed is not presented by a perfect curve with many fluctuations, which reveals some reasons. Firstly, the undeveloped technology cannot ensure a normal operation of maglev system in a high speed, leading to final failure in practical running. The second reason can be attributed to the policy changes leading to the change of development direction. Because the technology cannot satisfy the high- speed running, the government might encourage to study low-speed maglev train service. However, the both lines finally tend to be the same, which may indicate that the speed reaches the maximum at present technology level. The curve cannot totally represent the deployment or development level. However, the maglev trains still stay in the young age. In facts, under the condition that the track distance of maglev train and passenger ridership are weakness, speed as the most highlight of the maglev train can show the development level in the current stage. The speed may beed enhanced in the future contributions.