TY - JOUR
AU1 - Lu, Chun-fang
AB - Abstract: China’s high-speed railway network has already achieved speeds of 350 km/h; however, this could be further increased to 400 km/h. After considering the development status and technical level of the high-speed railway system in China, this study indicates that there are four key technologies involved in improving its operational speed: the track, the electrical moving unit, the control system and the traction power supply. Through an experimental analysis, an evaluation index for the high-speed railway is then constructed based on four aspects: safety, comfort, intelligence and environmental protection. Using this system, the rationality of the high-speed railway speed-improvement plan can be scientifically evaluated. The results are of practical significance to the Chinese railway administration, as they can be used to formulate specific plans to increase rail speeds, and therefore promote the rapid development of the high-speed railway network in China. Introduction The mid- to long-term rail development plan [1] was approved by the Chinese government in 2004 and adjusted in 2008. This plan clearly specified that the railway mileage in operation should reach 120 000 km by 2020, and that of the high-speed railway network should exceed 16 000 km. By the end of 2017, the total railway mileage in China was approximately 127 000 km, ranking second in the world, and included 66.3% of the world’s total high-speed rail mileage, approximately 25 000 km. Owing to certain human factors, the operational speed of the high-speed railway system in China decreased on 1 July 2011. However, the operational speed has now recovered to 350 km/h, which is the fastest in the world. China already has all the key technologies for a successful high-speed railway. However, the current focus of both scientists and passengers in China is the potential for further operational speed improvement, for instance to 400 km/h. Table 1 New spatial line type for a high-speed railway with an operational speed of 350 km/h Maximum slope . Plane radius of curvature (m) . Line spacing (m) . Minimum radius of vertical curvature (m) . 20‰ 7000 5.0 25 000 Maximum slope . Plane radius of curvature (m) . Line spacing (m) . Minimum radius of vertical curvature (m) . 20‰ 7000 5.0 25 000 Open in new tab Table 1 New spatial line type for a high-speed railway with an operational speed of 350 km/h Maximum slope . Plane radius of curvature (m) . Line spacing (m) . Minimum radius of vertical curvature (m) . 20‰ 7000 5.0 25 000 Maximum slope . Plane radius of curvature (m) . Line spacing (m) . Minimum radius of vertical curvature (m) . 20‰ 7000 5.0 25 000 Open in new tab Increases in the running speed of high-speed railways improve their operational efficiency and facilitate public transport. In addition, speed improvements are vital for the construction of metropolitan areas and for reinforcing the attraction of core cities. This article discusses the key techniques involved in speed improvement, and analyses the requirements for and feasibility of increasing railway speeds. Suggestions are proposed with respect to the required infrastructure enhancements and equipment upgrades. The article is organized as follows: the key technologies involved in improving operational speed are presented in Section 1, including the railway track, the electrical moving unit, the control system and the traction power supply system. Section 2 introduces the evaluation index for improvements in operational speed. The conclusions and implications of the current discussion are presented in Section 3. 1. Key technologies for improving operational speed Four technologies determine improvement in the operational speed of a high-speed railway system: the railway line or track, the electrical moving unit (EMU), the control system and the traction power supply. 1.1. Railway track A railway system includes the spatial line shape, bridges and tunnels, rail beds and tracks. Table 1 presents a new design for a spatial line for a railway with a speed of 350 km/h [3]. The railway track must be stable and smooth. Assuming the straight line type as the basic line condition, the selection of railway factors such as curvature, line spacing and vertical curve will directly affect operational speed and comfort. Factors such as tunnel, embarkment, and ail, are fundamental elements of a high-speed railway, bearing most of the load of trains. A high degree of smoothness and stability are key to ensuring the safe and stable operation of high-speed trains. The following three aspects therefore need to be considered during the design and construction of high-speed railways: (i) strength and stiffness, ability to withstand natural disasters and structural durability; (ii) settlement of the structure after construction (must be restricted to the order of millimetres); and (iii) geometric dimensions of the tracks (must be controlled to the order of millimetres). 1.2. Electrical moving unit (EMU) The operational speed and reliability of high-speed trains are determined by the relevant technologies of the EMU. The EMU must enable high speeds and be stable. According to the guidelines of the State Council, the China Railway Corporation (CRC) fosters the ideals of original and integrated innovation, along with the absorption and re-innovation of import technologies. Based on this, the CRH380 and Fuxing series of high-speed EMUs have been successfully manufactured since 2004, achieving operational speeds of over 350 km/h. The high-speed EMUs involve nine critical technologies—including the high-speed bogie, the aluminium-alloy train body, the control system, the traction converter, the traction transformer, the traction control system, the traction motor, the braking system and system integration—which are closely related with ten matching technologies, including the pantograph, the air-conditioning system, the hook and buffering devices, the door and window systems, the waste collection device, the interior decoration, the seating, the couplings between cars and the auxiliary system (see Fig. 1 for details). Fig. 1 Open in new tabDownload slide Critical and matching technologies of the high-speed EMU 1.3. Control system The control system of high-speed trains is responsible for controlling the operational speed, stops at stations, temporary stops and speed restriction according to the distance between trains, in order to ensure their regular and safe operation. The control system must therefore have the necessary degree of precision. The implementation of control tasks relies on the control system, which is an integrated communication technology. The control system involves a signal exchange between train and ground, on-board safety computers, wireless data transfer, wireless control devices and ground devices. The detailed structure of the control system is shown in Fig. 2. Fig. 2 Open in new tabDownload slide Composition of the EMU control system Fig. 3 Open in new tabDownload slide Traction power supply system 1.4. Traction power supply system The traction power supply system is responsible for the safe and reliable transfer of electricity from the national grid to the EMUs, thus providing continuous power for the EMUs’ high-speed operation. This system must have sufficient capacity and be reliable. The system consists of three main components, namely, the traction substations, contact network and the supervisory control and data acquisition (SCADA) system, which is involved with the contact network, the high-tension network, the remote-monitoring devices, the special connectors and the traction transformers, as shown in Fig. 3. Fig. 4 Open in new tabDownload slide Index system for improving high-speed railway speeds In summary, the key technological requirements for increasing the operational speed of a high-speed railway are a stable rail track, a fast EMU, precise control and an adequate power supply. The adaptability of these four technological components for speed improvement will be discussed based on test data in Section 2. Additionally, the construction and operation of a high-speed railway network is related with station buildings, customer service, natural disaster monitoring and warning, maintenance, dispatching and directing, all of which require system integration [5]. 2. Evaluation index for improving operational speed In order to establish the key technology systems and plan for speed improvements to the high-speed railway network, the rationality and applicability of the speed-improvement plan needs to be analysed by calculation and examination of the corresponding indices and experimental data. According to the manufacturing and operational realities of high-speed railways, the evaluation indices can be summarised as safety, comfort, intelligence and environmental protection, as shown in Fig. 4. 2.1. Safety Safety is a fundamental requirement and key factor in the normal operation of a high-speed railway, and is crucial for the development of the high-speed railway system in China. Multiple factors affect the operational safety of trains, such as natural disasters, intentional sabotage, and damage to the train body, bridges or tunnels. Improvements to the operational safety of trains should focus on protection, alerting, monitoring and especially derailment prevention [6]. To achieve these objectives, a safety index system covering all geometric dimensions and vehicle dynamic response is established. Operational safety evaluations of high-speed railway systems usually adopt only the vehicle dynamics index, as they are directly affected by errors in the geometric dimensions. Table 2 Comparison of operation and maintenance standard between China and EN (Partial) Parameter . Range wavelength (m) . China Standard (250–350 km/h) . Range menelength (m) . EN Standard (230–300 km/h) . Acceptance (mm) . Frequent maintenance (mm) . Temporary repair (mm) . Speed limit (200 km/h) . Standard maintenance value (mm) . Intervention value (mm) . Speed limit (mm) . Height 1.5–42 3 4 8 10 3–25 6–10 8–12 16 1.5–120 5 7 12 15 25–70 12–18 16–20 28 Direction of track 1.5–42 3 4 6 7 3–25 4–7 6–8 10 1.5–120 5 6 10 12 25–70 8–13 16–20 20 Track distance − −2/+3 −3/+4 −5/+7 −6/+8 − −3/+20 −4/+23 −5/+28 Horizontality − 3 5 7 8 − − − − Twist − 3 4 7 8 − 3 4 5 Parameter . Range wavelength (m) . China Standard (250–350 km/h) . Range menelength (m) . EN Standard (230–300 km/h) . Acceptance (mm) . Frequent maintenance (mm) . Temporary repair (mm) . Speed limit (200 km/h) . Standard maintenance value (mm) . Intervention value (mm) . Speed limit (mm) . Height 1.5–42 3 4 8 10 3–25 6–10 8–12 16 1.5–120 5 7 12 15 25–70 12–18 16–20 28 Direction of track 1.5–42 3 4 6 7 3–25 4–7 6–8 10 1.5–120 5 6 10 12 25–70 8–13 16–20 20 Track distance − −2/+3 −3/+4 −5/+7 −6/+8 − −3/+20 −4/+23 −5/+28 Horizontality − 3 5 7 8 − − − − Twist − 3 4 7 8 − 3 4 5 Open in new tab Table 2 Comparison of operation and maintenance standard between China and EN (Partial) Parameter . Range wavelength (m) . China Standard (250–350 km/h) . Range menelength (m) . EN Standard (230–300 km/h) . Acceptance (mm) . Frequent maintenance (mm) . Temporary repair (mm) . Speed limit (200 km/h) . Standard maintenance value (mm) . Intervention value (mm) . Speed limit (mm) . Height 1.5–42 3 4 8 10 3–25 6–10 8–12 16 1.5–120 5 7 12 15 25–70 12–18 16–20 28 Direction of track 1.5–42 3 4 6 7 3–25 4–7 6–8 10 1.5–120 5 6 10 12 25–70 8–13 16–20 20 Track distance − −2/+3 −3/+4 −5/+7 −6/+8 − −3/+20 −4/+23 −5/+28 Horizontality − 3 5 7 8 − − − − Twist − 3 4 7 8 − 3 4 5 Parameter . Range wavelength (m) . China Standard (250–350 km/h) . Range menelength (m) . EN Standard (230–300 km/h) . Acceptance (mm) . Frequent maintenance (mm) . Temporary repair (mm) . Speed limit (200 km/h) . Standard maintenance value (mm) . Intervention value (mm) . Speed limit (mm) . Height 1.5–42 3 4 8 10 3–25 6–10 8–12 16 1.5–120 5 7 12 15 25–70 12–18 16–20 28 Direction of track 1.5–42 3 4 6 7 3–25 4–7 6–8 10 1.5–120 5 6 10 12 25–70 8–13 16–20 20 Track distance − −2/+3 −3/+4 −5/+7 −6/+8 − −3/+20 −4/+23 −5/+28 Horizontality − 3 5 7 8 − − − − Twist − 3 4 7 8 − 3 4 5 Open in new tab Table 3 Values of allowable deviation for the TQI in China Design speed level (km/h) . Range wavelength (m) . TQI (mm) . Level I . Level II . 250–350 1.5–42 4 5 Design speed level (km/h) . Range wavelength (m) . TQI (mm) . Level I . Level II . 250–350 1.5–42 4 5 Open in new tab Table 3 Values of allowable deviation for the TQI in China Design speed level (km/h) . Range wavelength (m) . TQI (mm) . Level I . Level II . 250–350 1.5–42 4 5 Design speed level (km/h) . Range wavelength (m) . TQI (mm) . Level I . Level II . 250–350 1.5–42 4 5 Open in new tab (i) Index of geometric status of the track For evaluation of the track quality, long-term monitoring and tests on the track are conducted by means of the comprehensive dynamic detection system for track geometry used in China. Combining the experimental data and numerical simulations, a standard for operation and maintenance of the track geometry is established for speeds of 250 (not included)–350 km/h. Meanwhile, as listed in Table 2, a standard for work acceptance is also established, which is more restrictive than the standard for operation and maintenance. In China, the track is comprehensively evaluated using the track quality index (TQI), which is the summation of the standard deviation of the seven geometric errors over each 200 m section. The allowable deviation values of the TQI for track irregularity are listed in Table 3, and the calculation of the TQI is expressed as \begin{equation} TQI=\sum \limits_{i=1}^7\sqrt{\frac{1}{N}\sum \limits_{j=1}^N{\big({x}_{ij}-{\overline{x}}_i\big)}^2} \end{equation}(1) where xij is the magnitude of the geometric error, |${\overline{x}}_i$| is the arithmetic mean of xij and N is the number of sampling points (in a 200 m section). (ii) Index of safety performance of vehicle dynamics Fig. 5 Open in new tabDownload slide Index system for vehicle dynamic safety Table 4 Evaluation standard for vehicle dynamic performance Parameter . Evaluation content . Chinese standard . UIC standard . Derailment coefficient, Q/P Derailment safety |${\Big(\frac{Q}{P}\Big)}_{\mathrm{lim}}=0.8$| |${\Big[{\Big(\frac{Q}{P}\Big)}_{2m}\Big]}_{\mathrm{lim}}=0.8$| Rate of wheel load reduction,|$\Delta P/\overline{P}$| Derailment caused by load reduction of the wheels on one side |$\Delta P/\overline{P}\le 0.80$| — Transverse force in shaft, H (kN) Vehicle damage to track |${(H)}_{\mathrm{lim}}=10+\frac{P_0}{3}$| |${\Big(\sum {H}_{2m}\Big)}_{\mathrm{lim}}=10+\frac{P_0}{3}$| Transverse acceleration of frame (m/s2) Vehicle stability of transverse motion 0.5–10 Hz after filtering, unqualified if maximum value appears 6 times (inclusive) continuously, or exceeds 8 m/s2 0.5–10 Hz after filtering, unqualified if maximum value appears 6 times (inclusive) continuously, or exceeds 8–10 m/s2 Parameter . Evaluation content . Chinese standard . UIC standard . Derailment coefficient, Q/P Derailment safety |${\Big(\frac{Q}{P}\Big)}_{\mathrm{lim}}=0.8$| |${\Big[{\Big(\frac{Q}{P}\Big)}_{2m}\Big]}_{\mathrm{lim}}=0.8$| Rate of wheel load reduction,|$\Delta P/\overline{P}$| Derailment caused by load reduction of the wheels on one side |$\Delta P/\overline{P}\le 0.80$| — Transverse force in shaft, H (kN) Vehicle damage to track |${(H)}_{\mathrm{lim}}=10+\frac{P_0}{3}$| |${\Big(\sum {H}_{2m}\Big)}_{\mathrm{lim}}=10+\frac{P_0}{3}$| Transverse acceleration of frame (m/s2) Vehicle stability of transverse motion 0.5–10 Hz after filtering, unqualified if maximum value appears 6 times (inclusive) continuously, or exceeds 8 m/s2 0.5–10 Hz after filtering, unqualified if maximum value appears 6 times (inclusive) continuously, or exceeds 8–10 m/s2 Open in new tab Table 4 Evaluation standard for vehicle dynamic performance Parameter . Evaluation content . Chinese standard . UIC standard . Derailment coefficient, Q/P Derailment safety |${\Big(\frac{Q}{P}\Big)}_{\mathrm{lim}}=0.8$| |${\Big[{\Big(\frac{Q}{P}\Big)}_{2m}\Big]}_{\mathrm{lim}}=0.8$| Rate of wheel load reduction,|$\Delta P/\overline{P}$| Derailment caused by load reduction of the wheels on one side |$\Delta P/\overline{P}\le 0.80$| — Transverse force in shaft, H (kN) Vehicle damage to track |${(H)}_{\mathrm{lim}}=10+\frac{P_0}{3}$| |${\Big(\sum {H}_{2m}\Big)}_{\mathrm{lim}}=10+\frac{P_0}{3}$| Transverse acceleration of frame (m/s2) Vehicle stability of transverse motion 0.5–10 Hz after filtering, unqualified if maximum value appears 6 times (inclusive) continuously, or exceeds 8 m/s2 0.5–10 Hz after filtering, unqualified if maximum value appears 6 times (inclusive) continuously, or exceeds 8–10 m/s2 Parameter . Evaluation content . Chinese standard . UIC standard . Derailment coefficient, Q/P Derailment safety |${\Big(\frac{Q}{P}\Big)}_{\mathrm{lim}}=0.8$| |${\Big[{\Big(\frac{Q}{P}\Big)}_{2m}\Big]}_{\mathrm{lim}}=0.8$| Rate of wheel load reduction,|$\Delta P/\overline{P}$| Derailment caused by load reduction of the wheels on one side |$\Delta P/\overline{P}\le 0.80$| — Transverse force in shaft, H (kN) Vehicle damage to track |${(H)}_{\mathrm{lim}}=10+\frac{P_0}{3}$| |${\Big(\sum {H}_{2m}\Big)}_{\mathrm{lim}}=10+\frac{P_0}{3}$| Transverse acceleration of frame (m/s2) Vehicle stability of transverse motion 0.5–10 Hz after filtering, unqualified if maximum value appears 6 times (inclusive) continuously, or exceeds 8 m/s2 0.5–10 Hz after filtering, unqualified if maximum value appears 6 times (inclusive) continuously, or exceeds 8–10 m/s2 Open in new tab In terms of vehicle dynamics, the evaluation indices of operational safety for a high-speed railway system consist mainly of derailment safety and hunting instability of the vehicle transverse motion [8]. Derailment safety consists of three indices: the derailment coefficient, the rate of wheel load reduction and the transverse force of the shaft. Hunting instability is usually expressed using the transverse acceleration of the vehicle frame. Of these indices, the derailment coefficient is used primarily for evaluating derailment safety, the rate of load reduction is used for evaluating derailment caused by load reduction of the wheels on one side, and the transverse acceleration is used for evaluating the stability of the vehicle’s transverse motion [9]. Fig. 5 and Table 4 present the index system for vehicle dynamic safety and the evaluation standard of the corresponding indices, respectively. For instance, a crossing test consisting of two trains travelling at a speed of 420 km/h was conducted on the high-speed railway line from Zhengzhou to Xuzhou in 2016, whose design speed was 350 km/h. The test was conducted using two Fuxing EMUs: the CRH-0207 and the CRH-0503. It can be seen from Table 5 that the values of the derailment coefficient, the rate of wheel load reduction, the shaft transverse force and the transverse acceleration of the frame satisfy the requirements of the safety indices. Fig. 6 shows that the transverse acceleration of the frame is linearly proportional to the operational speed within the range of 200–400 km/h. Neither the transverse force nor the transverse acceleration exceed the corresponding limits. Note that train safety is not affected if the rate of load reduction exceeds the limit, while the transverse force is much lower than its limit (66 kN). Operational safety is challenged when both the transverse force and the rate of load reduction approach the limits, which was not observed during the field test. Table 5 Maximum stability index on the 2nd shaft of 7th car for trains operating westbound on Zhengzhou–Xuzhou passenger line Line condition . Derailment coefficient . . Rate of wheel load reduction . . Shaft transverse force (kN) . . Vertical force between wheel and rail (kN) . Max. value . Speed (km/h) . . Max. value . Speed (km/h) . . Max. value . Speed (km/h) . . Max. value . Speed (km/h) . Straight 0.51 290 0.87 410 32.70 400 166.87 390 R7000m 0.18 380/390 0.76 390 23.89 380 136.38 330 R8000m 0.32 320 0.90 370 27.58 390 151.51 350 R9000m 0.34 420 0.88 410 25.98 410 159.43 240 R10000m 0.24 400 0.72 410 21.21 410 134.01 390 Line condition . Derailment coefficient . . Rate of wheel load reduction . . Shaft transverse force (kN) . . Vertical force between wheel and rail (kN) . Max. value . Speed (km/h) . . Max. value . Speed (km/h) . . Max. value . Speed (km/h) . . Max. value . Speed (km/h) . Straight 0.51 290 0.87 410 32.70 400 166.87 390 R7000m 0.18 380/390 0.76 390 23.89 380 136.38 330 R8000m 0.32 320 0.90 370 27.58 390 151.51 350 R9000m 0.34 420 0.88 410 25.98 410 159.43 240 R10000m 0.24 400 0.72 410 21.21 410 134.01 390 Open in new tab Table 5 Maximum stability index on the 2nd shaft of 7th car for trains operating westbound on Zhengzhou–Xuzhou passenger line Line condition . Derailment coefficient . . Rate of wheel load reduction . . Shaft transverse force (kN) . . Vertical force between wheel and rail (kN) . Max. value . Speed (km/h) . . Max. value . Speed (km/h) . . Max. value . Speed (km/h) . . Max. value . Speed (km/h) . Straight 0.51 290 0.87 410 32.70 400 166.87 390 R7000m 0.18 380/390 0.76 390 23.89 380 136.38 330 R8000m 0.32 320 0.90 370 27.58 390 151.51 350 R9000m 0.34 420 0.88 410 25.98 410 159.43 240 R10000m 0.24 400 0.72 410 21.21 410 134.01 390 Line condition . Derailment coefficient . . Rate of wheel load reduction . . Shaft transverse force (kN) . . Vertical force between wheel and rail (kN) . Max. value . Speed (km/h) . . Max. value . Speed (km/h) . . Max. value . Speed (km/h) . . Max. value . Speed (km/h) . Straight 0.51 290 0.87 410 32.70 400 166.87 390 R7000m 0.18 380/390 0.76 390 23.89 380 136.38 330 R8000m 0.32 320 0.90 370 27.58 390 151.51 350 R9000m 0.34 420 0.88 410 25.98 410 159.43 240 R10000m 0.24 400 0.72 410 21.21 410 134.01 390 Open in new tab Fig. 6 Open in new tabDownload slide Average transverse acceleration of the frame in the CRH-0207 EMU at different speeds. The regression analysis is conducted between the lateral force and different speed levels 2.2. Comfort The rapid development of high-speed trains in China has made public transportation far more convenient. In addition to speed and safety issues, comfort has become an increasing concern for rail passengers. Nowadays, passenger cars require not only high speed and safety levels. Passenger comfort has also become a key index of service quality. The comfort of passengers on high-speed trains must therefore also be studied [10]. The factors influencing passenger comfort comprise 12 categories, including noise, vibration, transient pressure change, sanitary facilities, humidity and temperature. A detailed description is shown in Fig. 7. Fig. 7 Open in new tabDownload slide Factors influencing passenger comfort on railway vehicles A comfort index system (Fig. 8) has been established based on the influence scale, influence time and importance of each factor influencing passenger comfort. The index system includes six main parameters: vehicle stability, transient pressure change, electromagnetic environment, vehicle noise, brake-induced impulse motion and centrifugal force on a curve. All these parameters will be discussed below. Fig. 8 Open in new tabDownload slide Comfort index system (i) Vehicle stability The vehicle operating stability parameter evaluates the smoothness of operation. The key factors in vehicle operating stability include vehicle vibration acceleration, the vehicle stability index and the vehicle vibration comfort index. (a) Vehicle vibration acceleration Railway vehicle vibration acceleration consists of lateral frame-vibration acceleration and vertical frame-vibration acceleration, whose limits are listed in Table 6. Fig. 9 shows the acceleration data recorded for the CRH-0503 EMU operating on the Zhengzhou–Xuzhou high-speed railway line. According to the results shown in Fig. 9, all measured acceleration data satisfies the requirement of the maximum limits specified in Table 6. Table 6 Vehicle vibration acceleration index limits Vertical vibration acceleration (m/s2) . Lateral vibration acceleration (m/s2) . ≤ 2.5 ≤ 2.5 Vertical vibration acceleration (m/s2) . Lateral vibration acceleration (m/s2) . ≤ 2.5 ≤ 2.5 Open in new tab Table 6 Vehicle vibration acceleration index limits Vertical vibration acceleration (m/s2) . Lateral vibration acceleration (m/s2) . ≤ 2.5 ≤ 2.5 Vertical vibration acceleration (m/s2) . Lateral vibration acceleration (m/s2) . ≤ 2.5 ≤ 2.5 Open in new tab Fig. 9 Open in new tabDownload slide Vehicle vibration acceleration for the Fuxing EMU operating on the Zhengzhou–Xuzhou passenger-dedicated line: (a) CRH-0503 Zhengzhou–Xuzhou passenger line no-load experiment Tc08 operating westbound, vertical direction; (b) CRH-0503 Zhengzhou–Xuzhou passenger line no-load experiment Tc08 operating eastbound, lateral direction (b) Vehicle stability index The vehicle stability index describes the steadiness of railway vehicles in operation. Stability can be divided into lateral stability and vertical stability. The stability index can be calculated using Equation (2). The calculated stability indices are listed in Table 7. \begin{equation} W=0.896\sqrt[n]{\frac{a^3}{f}F(\,f)} \end{equation}(2) Table 7 Stability index limit Index . Limit (excellent level) . Stability index < 2.5 Index . Limit (excellent level) . Stability index < 2.5 Open in new tab Table 7 Stability index limit Index . Limit (excellent level) . Stability index < 2.5 Index . Limit (excellent level) . Stability index < 2.5 Open in new tab In Equation (2), a is the vehicle vibration acceleration, f is the vibration frequency and F(f) is the weighting coefficient related with the vibration frequency. Fig. 10 shows the data recorded for the Fuxing EMU operating on the Zhengzhou–Xuzhou passenger-dedicated line, which all falls within the excellent level of the vibration-acceleration index. Fig. 10 Open in new tabDownload slide Experimentally measured vehicle stability for the Fuxing EMU operating on the Zhengzhou–Xuzhou passenger-dedicated line Fig. 11 Open in new tabDownload slide Recorded vehicle vibration comfort index (NMV) for the CRH-380A EMU operating on the Beijing–Shanghai high-speed lines (c) Vehicle vibration comfort index Vehicle vibration comfort refers to the vibration frequency during vehicle operation that makes the passenger feel comfortable. Vehicle vibration comfort can be evaluated using the vehicle vibration index. Fig. 11 shows the vehicle vibration comfort data (NMV) recorded for the CRH-380A operating on the Beijing–Shanghai high-speed lines. It can be seen that when vehicles are operating between 200 and 350 km/h, the vehicle vibration comfort index satisfies the excellent limit with levels of NMV ≤ 2.0. This vehicle vibration comfort index can be calculated as follows: \begin{equation} {N}_{MV}=6\sqrt{{\left({a}_{XP95}^{W_d}\right)}^2+{\left({a}_{YP95}^{W_d}\right)}^2+{\left({a}_{ZP95}^{W_d}\right)}^2} \end{equation}(3) where aXP, aYP and aZP represent acceleration on the ground plane in three directions. Based on the experimentally measured results for the CRH-380A and the vehicle vibration comfort index calculated using Equation (3), when a train is operating at a speed of 400 km/h, vehicle vibration comfort satisfies the requirement of NMV = 2.0. (ii) Transient pressure change The transient pressure change can be evaluated using the aerodynamic comfort of the vehicle. Table 8 presents the transient pressure change standard. The Fuxing EMU applies the same standard as the UIC for transient pressure change inside a vehicle. Table 8 Transient pressure change standard inside the vehicle Parameter . Pressure (Pa) . Time interval (s) . Chinese standard for EMU transient pressure change (temporary) 500 1 800 3 UIC 660 500 1 800 3 Parameter . Pressure (Pa) . Time interval (s) . Chinese standard for EMU transient pressure change (temporary) 500 1 800 3 UIC 660 500 1 800 3 Open in new tab Table 8 Transient pressure change standard inside the vehicle Parameter . Pressure (Pa) . Time interval (s) . Chinese standard for EMU transient pressure change (temporary) 500 1 800 3 UIC 660 500 1 800 3 Parameter . Pressure (Pa) . Time interval (s) . Chinese standard for EMU transient pressure change (temporary) 500 1 800 3 UIC 660 500 1 800 3 Open in new tab Table 9 Transient pressure change for vehicles operating on different lines Line . Vehicle type . Maximum pressure change within 1 s (Pa) . Maximum pressure change within 3 s (Pa) . Vehicle operating through a tunnel at 350 km/h (Datong–Xi’an Line) CRH-0207 181 205 CRH-0503 246 280 Vehicles crossing at 420 km/h (Zhengzhou–Xuzhou Line) CRH-0207 93 106 CRH-0503 93 106 Vehicle operating through a tunnel at 350 km/h (Beijing–Shanghai) CRH-380A − 464 Limit 500 800 Line . Vehicle type . Maximum pressure change within 1 s (Pa) . Maximum pressure change within 3 s (Pa) . Vehicle operating through a tunnel at 350 km/h (Datong–Xi’an Line) CRH-0207 181 205 CRH-0503 246 280 Vehicles crossing at 420 km/h (Zhengzhou–Xuzhou Line) CRH-0207 93 106 CRH-0503 93 106 Vehicle operating through a tunnel at 350 km/h (Beijing–Shanghai) CRH-380A − 464 Limit 500 800 Open in new tab Table 9 Transient pressure change for vehicles operating on different lines Line . Vehicle type . Maximum pressure change within 1 s (Pa) . Maximum pressure change within 3 s (Pa) . Vehicle operating through a tunnel at 350 km/h (Datong–Xi’an Line) CRH-0207 181 205 CRH-0503 246 280 Vehicles crossing at 420 km/h (Zhengzhou–Xuzhou Line) CRH-0207 93 106 CRH-0503 93 106 Vehicle operating through a tunnel at 350 km/h (Beijing–Shanghai) CRH-380A − 464 Limit 500 800 Line . Vehicle type . Maximum pressure change within 1 s (Pa) . Maximum pressure change within 3 s (Pa) . Vehicle operating through a tunnel at 350 km/h (Datong–Xi’an Line) CRH-0207 181 205 CRH-0503 246 280 Vehicles crossing at 420 km/h (Zhengzhou–Xuzhou Line) CRH-0207 93 106 CRH-0503 93 106 Vehicle operating through a tunnel at 350 km/h (Beijing–Shanghai) CRH-380A − 464 Limit 500 800 Open in new tab Table 10 Low frequency magnetic field limit in EMU Limit . Power frequency electric field intensity(V/m) . Power frequency magnetic field intensity(μT) . China 4000 100 ICNIRP 5000 200 Limit . Power frequency electric field intensity(V/m) . Power frequency magnetic field intensity(μT) . China 4000 100 ICNIRP 5000 200 Open in new tab Table 10 Low frequency magnetic field limit in EMU Limit . Power frequency electric field intensity(V/m) . Power frequency magnetic field intensity(μT) . China 4000 100 ICNIRP 5000 200 Limit . Power frequency electric field intensity(V/m) . Power frequency magnetic field intensity(μT) . China 4000 100 ICNIRP 5000 200 Open in new tab Fig. 12 Open in new tabDownload slide Recorded magnetic field intensity for high-speed EMUs China’s high-speed trains have an excellent aerodynamic comfort level. For example, after the transient pressure changes for trains operating in a tunnel or for a crossing involving different type of trains were measured and calculated (results listed in Table 9), all the transient pressure changes inside the vehicles were found to meet the standard specified in Table 8. (iii) Electromagnetic environment Electromagnetic radiation affects both crew and passengers in the railway vehicle. Consequently, China Railway has set out limits on the magnetic field permissible inside the train in its ‘Low-Frequency Magnetic Field Limit and Measurement in EMUs’ handbook. This regulation specifies a strict limit on the magnetic field level inside vehicles. The limit value is presented in Table 10. Fig. 12 shows the results for the CRH-380A, CRH-0207 and CRH-0503 vehicles, which indicate that all magnetic field levels inside the vehicles meet the limit set out in Table 10. (iv) Vehicle noise Vehicle noise can affect the comfort of passengers in the vehicle, as well as the quality of the vehicle broadcasting system. The Chinese national standard for vehicle noise levels is similar to the UIC standard (both are listed in Table 11). Table 11 China’s national standard on noise limit inside of vehicles Speed (km/h) . Driver’s cabin . . Middle of passenger compartment . GB/T3450 . UIC 651 . . GB/T12816 . UIC 660 . 350 78 − 68 − 300 78 78 (Target: 75) 68 68 (Target: 65) Speed (km/h) . Driver’s cabin . . Middle of passenger compartment . GB/T3450 . UIC 651 . . GB/T12816 . UIC 660 . 350 78 − 68 − 300 78 78 (Target: 75) 68 68 (Target: 65) Open in new tab Table 11 China’s national standard on noise limit inside of vehicles Speed (km/h) . Driver’s cabin . . Middle of passenger compartment . GB/T3450 . UIC 651 . . GB/T12816 . UIC 660 . 350 78 − 68 − 300 78 78 (Target: 75) 68 68 (Target: 65) Speed (km/h) . Driver’s cabin . . Middle of passenger compartment . GB/T3450 . UIC 651 . . GB/T12816 . UIC 660 . 350 78 − 68 − 300 78 78 (Target: 75) 68 68 (Target: 65) Open in new tab Table 12 Vehicle noise for different type of EMUs operating in different lines Working condition . CRH . Speed (km/h) . Driver’s Cabin . Middle of passenger compartment . China Standard EMU (Datong–Xi’an) CRH-0207 300 74 65 CRH-0503 300 72 64 CRH-0207 300 72.2 65.4 350 75.8 67 China standard EMU 400 78.4 69.2 (Zhengzhou–Xuzhou) 300 71.9 62.5 CRH-0503 350 75.5 66.5 400 77.1 68.3 CRH-380A (Beijing–Shanghai) 300 77 68 Limit 350 78 68 Working condition . CRH . Speed (km/h) . Driver’s Cabin . Middle of passenger compartment . China Standard EMU (Datong–Xi’an) CRH-0207 300 74 65 CRH-0503 300 72 64 CRH-0207 300 72.2 65.4 350 75.8 67 China standard EMU 400 78.4 69.2 (Zhengzhou–Xuzhou) 300 71.9 62.5 CRH-0503 350 75.5 66.5 400 77.1 68.3 CRH-380A (Beijing–Shanghai) 300 77 68 Limit 350 78 68 Open in new tab Table 12 Vehicle noise for different type of EMUs operating in different lines Working condition . CRH . Speed (km/h) . Driver’s Cabin . Middle of passenger compartment . China Standard EMU (Datong–Xi’an) CRH-0207 300 74 65 CRH-0503 300 72 64 CRH-0207 300 72.2 65.4 350 75.8 67 China standard EMU 400 78.4 69.2 (Zhengzhou–Xuzhou) 300 71.9 62.5 CRH-0503 350 75.5 66.5 400 77.1 68.3 CRH-380A (Beijing–Shanghai) 300 77 68 Limit 350 78 68 Working condition . CRH . Speed (km/h) . Driver’s Cabin . Middle of passenger compartment . China Standard EMU (Datong–Xi’an) CRH-0207 300 74 65 CRH-0503 300 72 64 CRH-0207 300 72.2 65.4 350 75.8 67 China standard EMU 400 78.4 69.2 (Zhengzhou–Xuzhou) 300 71.9 62.5 CRH-0503 350 75.5 66.5 400 77.1 68.3 CRH-380A (Beijing–Shanghai) 300 77 68 Limit 350 78 68 Open in new tab Table 13 Vehicle noise level under different testing speeds Testing vehicle . Speed (km/h) . Driver’s cabin . Middle of passenger compartment . End of passenger compartment . (Zhengzhou–Xuzhou passenger line CRH-0207) 300 73 63 66 350 76 67 69 380 77 68 71 400 78 69 72 420 79 70 73 (Zhengzhou–Xuzhou passenger line CRH-0503) 300 71 62 67 350 75 66 70 380 76 67 71 400 77 68 72 420 79 69 73 (Beijing–Shanghai high speed line CRH-380A-6041L) 300 76 66 69–70 350 79 68 69–72 380 81 70 72–74 400 − 70 72 420 − 71 73 Testing vehicle . Speed (km/h) . Driver’s cabin . Middle of passenger compartment . End of passenger compartment . (Zhengzhou–Xuzhou passenger line CRH-0207) 300 73 63 66 350 76 67 69 380 77 68 71 400 78 69 72 420 79 70 73 (Zhengzhou–Xuzhou passenger line CRH-0503) 300 71 62 67 350 75 66 70 380 76 67 71 400 77 68 72 420 79 69 73 (Beijing–Shanghai high speed line CRH-380A-6041L) 300 76 66 69–70 350 79 68 69–72 380 81 70 72–74 400 − 70 72 420 − 71 73 Open in new tab Table 13 Vehicle noise level under different testing speeds Testing vehicle . Speed (km/h) . Driver’s cabin . Middle of passenger compartment . End of passenger compartment . (Zhengzhou–Xuzhou passenger line CRH-0207) 300 73 63 66 350 76 67 69 380 77 68 71 400 78 69 72 420 79 70 73 (Zhengzhou–Xuzhou passenger line CRH-0503) 300 71 62 67 350 75 66 70 380 76 67 71 400 77 68 72 420 79 69 73 (Beijing–Shanghai high speed line CRH-380A-6041L) 300 76 66 69–70 350 79 68 69–72 380 81 70 72–74 400 − 70 72 420 − 71 73 Testing vehicle . Speed (km/h) . Driver’s cabin . Middle of passenger compartment . End of passenger compartment . (Zhengzhou–Xuzhou passenger line CRH-0207) 300 73 63 66 350 76 67 69 380 77 68 71 400 78 69 72 420 79 70 73 (Zhengzhou–Xuzhou passenger line CRH-0503) 300 71 62 67 350 75 66 70 380 76 67 71 400 77 68 72 420 79 69 73 (Beijing–Shanghai high speed line CRH-380A-6041L) 300 76 66 69–70 350 79 68 69–72 380 81 70 72–74 400 − 70 72 420 − 71 73 Open in new tab The experimental results show that Fuxing EMUs operating at 300 km/h and 350 km/h satisfy the noise limit set by the Chinese national standard, as presented in Table 12. The noise limit for trains operating at 400 km/h is not specified in the standard. The vehicle noise level of the CRH-380A operating at a speed of 300 km/h satisfies the limit set by the Chinese standard. The Fuxing EMU has a significantly lower noise level than that of the CRH-380A. Table 13 lists the noise data recorded for three different vehicle types in the driver’s cabin, the middle of the passenger compartment and the end of the passenger compartment. (v) Brake-induced impulse motion When a brake operation is applied on an EMU, an impulse motion will be induced along the vehicle’s direction of travel. According to the Interim Technical Conditions for China Railway the impulse-motion limit for trains under normal or emergency brake conditions is ≤0.75 m/s3. The longitudinal impact rates of the common brake and the emergency brake measured during the CRC tests satisfy this requirement. In the designs of both air and air–electric composite EMU braking systems in China, the braking force is controlled by a time constant. Taking the CRH-380BL as an example, the maximum emergency braking deceleration of this EMU is no more than 1.4 m/s2, and the vehicle thus meets passenger comfort requirements when braking, as shown in Fig. 13. Fig. 13 Open in new tabDownload slide Emergency braking deceleration for the CRH-380 EMU (vi) Curve centrifugal force To avoid passenger discomfort when passing a curve, it is necessary to raise the outer side of the curve appropriately, that is, superelevation of the outer rail is required. However, the superelevation must not be too great, because when the train stops on a curve with a superelevation of 200 mm and above, the passengers will feel unstable when standing and will experience difficulty walking and feelings of dizziness and discomfort. For this reason, Chinese high-speed railway design regulations specify that the maximum superelevation value allowable is 175 mm. As a result, the superelevation of the outer rail will be inadequate. When the train passes the curve, passenger comfort is closely related to the superelevation. Based on a number of studies, China Railway has specified the permissible value of the superelevation, as listed in Tables 14 and 15. Table 14 Relationship between comfort and inadequate superelevation Parameter . Comfort level 1 . Comfort level 2 . Comfort level 3 . Physical sensation No feeling Slight feeling Obvious feeling Corresponding comfort index 0.5 1.0 1.5 Corresponding unbalanced acceleration (g) 0.03 0.054 0.077 Corresponding inadequate superelevation (mm) 45 81 115 Parameter . Comfort level 1 . Comfort level 2 . Comfort level 3 . Physical sensation No feeling Slight feeling Obvious feeling Corresponding comfort index 0.5 1.0 1.5 Corresponding unbalanced acceleration (g) 0.03 0.054 0.077 Corresponding inadequate superelevation (mm) 45 81 115 Open in new tab Table 14 Relationship between comfort and inadequate superelevation Parameter . Comfort level 1 . Comfort level 2 . Comfort level 3 . Physical sensation No feeling Slight feeling Obvious feeling Corresponding comfort index 0.5 1.0 1.5 Corresponding unbalanced acceleration (g) 0.03 0.054 0.077 Corresponding inadequate superelevation (mm) 45 81 115 Parameter . Comfort level 1 . Comfort level 2 . Comfort level 3 . Physical sensation No feeling Slight feeling Obvious feeling Corresponding comfort index 0.5 1.0 1.5 Corresponding unbalanced acceleration (g) 0.03 0.054 0.077 Corresponding inadequate superelevation (mm) 45 81 115 Open in new tab Table 15 Inadequate superelevation allowable values specified in the High-Speed Railway Design Code Comfort condition . Permissible value of inadequate superelevation (mm) . Excellent 40 Good 60 General 90 Comfort condition . Permissible value of inadequate superelevation (mm) . Excellent 40 Good 60 General 90 Open in new tab Table 15 Inadequate superelevation allowable values specified in the High-Speed Railway Design Code Comfort condition . Permissible value of inadequate superelevation (mm) . Excellent 40 Good 60 General 90 Comfort condition . Permissible value of inadequate superelevation (mm) . Excellent 40 Good 60 General 90 Open in new tab The braking and longitudinal impulse and curve centrifugal force indices were not tested during the Zhengzhou–Xuzhou test, but the longitudinal impact did not change because the braking force of the EMU was fixed. However, the curve centrifugal force index deteriorates because the superelevation curve is not changed, and the curve centrifugal force increases after the speed increases. For example, at a radius of 7000 m, the superelevation is 175 mm, and when the speed is 350 km/h, the inadequate superelevation is 31.5 mm, and passenger comfort falls within the excellent level. When the speed is 420 km/h, the inadequate superelevation is 122.4 mm, and the human body feels uncomfortable. 2.3. Intelligence High-speed railway intelligence is based on a comprehensive understanding of the various elements (including people, vehicles, lines, environment and information) in the high-speed rail transportation system based on next-generation information technologies, such as the Internet of Things, big data and cloud computing, and the way in which these systems work together efficiently [11]. The intelligent high-speed railway has a foundation with considerable development potential, and the indicator system is continuously updated. The current indicator system is qualitative, quantitative, realistic and future-oriented. The main elements of this system are as follows: (i) Facial-recognition system allowing access to the station in less than 2 s; (ii) Intelligent card system; (iii) Automatic driving system; (iv) Full Wi-Fi coverage; (v) Impenetrable security; (vi) Big data sharing platform for passenger transportation, with 50% of passenger transportation data merged with the national big data platform; (vii) Full coverage of mobile passenger information terminals; (viii) Fully applied building information management (BIM) technology, with online monitoring applications for 100% of bridges, tunnels, roads and vehicles; (ix) Dynamic operation chart programming, allowing for driving on demand; (x) Itinerary planning and information services; and (xi) Station environment surveillance (illegal intrusion identification, crowd gathering and diffusion identification, etc.). 2.4. Environmental protection (i) Vibration noise The train’s vibration noise can be judged by the radiated noise of the vehicle and environmental vibration parameters. Among these parameters, environmental vibration is an environmental ground motion with a small amplitude (only a few micrometres) caused by traffic interference or mechanical vibration generated by the train. Standards commonly used to determine the dynamic characteristics of the site and the engineering structure are the train operation radiation noise evaluation criteria and environmental vibration evaluation criteria, listed in Tables 16 and 17. Table 16 Evaluation criteria for radiation noise of train operation (limit requirement) V . Radiated sound level when the train passes . TEL/dB (A) . 250 km/h 1 ≤ 90 2 ≤ 88 3 ≤ 86 300 km/h 1 ≤ 93 2 ≤ 91 3 ≤ 89 1 ≤ 94 350 km/h 2 ≤ 92 3 ≤ 90 V . Radiated sound level when the train passes . TEL/dB (A) . 250 km/h 1 ≤ 90 2 ≤ 88 3 ≤ 86 300 km/h 1 ≤ 93 2 ≤ 91 3 ≤ 89 1 ≤ 94 350 km/h 2 ≤ 92 3 ≤ 90 Open in new tab Table 16 Evaluation criteria for radiation noise of train operation (limit requirement) V . Radiated sound level when the train passes . TEL/dB (A) . 250 km/h 1 ≤ 90 2 ≤ 88 3 ≤ 86 300 km/h 1 ≤ 93 2 ≤ 91 3 ≤ 89 1 ≤ 94 350 km/h 2 ≤ 92 3 ≤ 90 V . Radiated sound level when the train passes . TEL/dB (A) . 250 km/h 1 ≤ 90 2 ≤ 88 3 ≤ 86 300 km/h 1 ≤ 93 2 ≤ 91 3 ≤ 89 1 ≤ 94 350 km/h 2 ≤ 92 3 ≤ 90 Open in new tab Table 17 Environmental vibration evaluation criteria Item . Test parameter . Judging limit requirement . Railway environmental vibration test Maximum Z vibration level when train passes VLZ, max ≤8 0 dB Item . Test parameter . Judging limit requirement . Railway environmental vibration test Maximum Z vibration level when train passes VLZ, max ≤8 0 dB Open in new tab Table 17 Environmental vibration evaluation criteria Item . Test parameter . Judging limit requirement . Railway environmental vibration test Maximum Z vibration level when train passes VLZ, max ≤8 0 dB Item . Test parameter . Judging limit requirement . Railway environmental vibration test Maximum Z vibration level when train passes VLZ, max ≤8 0 dB Open in new tab The noise time-domain curve for the CRH-0207 at different points (7.5 m, 15 m, 25 m, 60 m and 90 m from the centre line of outer rail, and 3.5 m above the rail surface) when passing over a typical bridge section at different speeds (300 km/h, 350 km/h, 400 km/h and 420 km/h) is shown in Fig. 14. Combined with the noise values at different speeds for the Zhengzhou–Xuzhou passenger-dedicated line and the Beijing–Shanghai pilot sections, when the speed is 400 km/h and 420 km/h, the noise at 25 m from the centre of the line is approximately 96 dB and 97 dB, respectively, which is higher than the standard of 94 dB for a speed of 350 km/h (Table 18). Table 18 Noise values at different speeds for the Zhengzhou–Xuzhou passenger-dedicated line and the Beijing–Shanghai pilot segments (dB) Speed (km/h) . Zhengzhou–Xuzhou passenger-dedicated line . Beijing–Shanghai pilot sections . CRH-0207 . CRH-0503 . CRH-380AL . CRH-380BL . 300 91.0 91.5 93.5 94.8 310 91.3 92.2 92.8 96.2 320 91.7 92.7 93.8 94.8 330 92.1 92.9 94.6 / 340 92.5 93.6 95.3 94.7 350 93.3 94.4 95.7 96.4 360 93.7 94.9 95.9 95.4 370 94.2 95.2 96.5 97.1 380 94.7 95.6 97.4 98.8 390 95.2 96.3 98.0 99.4 400 96.0 96.9 98.4 99.7 410 96.4 97.3 98.3 − 420 96.8 97.7 99.5 − Speed (km/h) . Zhengzhou–Xuzhou passenger-dedicated line . Beijing–Shanghai pilot sections . CRH-0207 . CRH-0503 . CRH-380AL . CRH-380BL . 300 91.0 91.5 93.5 94.8 310 91.3 92.2 92.8 96.2 320 91.7 92.7 93.8 94.8 330 92.1 92.9 94.6 / 340 92.5 93.6 95.3 94.7 350 93.3 94.4 95.7 96.4 360 93.7 94.9 95.9 95.4 370 94.2 95.2 96.5 97.1 380 94.7 95.6 97.4 98.8 390 95.2 96.3 98.0 99.4 400 96.0 96.9 98.4 99.7 410 96.4 97.3 98.3 − 420 96.8 97.7 99.5 − Open in new tab Table 18 Noise values at different speeds for the Zhengzhou–Xuzhou passenger-dedicated line and the Beijing–Shanghai pilot segments (dB) Speed (km/h) . Zhengzhou–Xuzhou passenger-dedicated line . Beijing–Shanghai pilot sections . CRH-0207 . CRH-0503 . CRH-380AL . CRH-380BL . 300 91.0 91.5 93.5 94.8 310 91.3 92.2 92.8 96.2 320 91.7 92.7 93.8 94.8 330 92.1 92.9 94.6 / 340 92.5 93.6 95.3 94.7 350 93.3 94.4 95.7 96.4 360 93.7 94.9 95.9 95.4 370 94.2 95.2 96.5 97.1 380 94.7 95.6 97.4 98.8 390 95.2 96.3 98.0 99.4 400 96.0 96.9 98.4 99.7 410 96.4 97.3 98.3 − 420 96.8 97.7 99.5 − Speed (km/h) . Zhengzhou–Xuzhou passenger-dedicated line . Beijing–Shanghai pilot sections . CRH-0207 . CRH-0503 . CRH-380AL . CRH-380BL . 300 91.0 91.5 93.5 94.8 310 91.3 92.2 92.8 96.2 320 91.7 92.7 93.8 94.8 330 92.1 92.9 94.6 / 340 92.5 93.6 95.3 94.7 350 93.3 94.4 95.7 96.4 360 93.7 94.9 95.9 95.4 370 94.2 95.2 96.5 97.1 380 94.7 95.6 97.4 98.8 390 95.2 96.3 98.0 99.4 400 96.0 96.9 98.4 99.7 410 96.4 97.3 98.3 − 420 96.8 97.7 99.5 − Open in new tab Fig. 14 Open in new tabDownload slide Noise time-domain curve at various distances for the CRH-0207 EMU: (a) speed of 300 km/h; (b) speed of 350 km/h; (c) speed of 400 km/h; (d): speed of 420 km/h (ii) Energy consumption Energy consumption is also an important indicator of a train’s green status. The per capita energy consumption results for the CRH-0207 and CRH-0503 on a flat road are shown in Figs 15 and 16. As can be seen from the figures, for the CRH-0207, the per capita energy consumption over 100 km (5.11 kWh) at 420 km/h is 44% higher than the energy consumption (3.55 kWh) at a speed of 350 km/h. The CRH-0503 has a value of 5.603 kWh of per capita energy consumption at 420 km/h, which is 43.5% higher than the energy consumption (3.905 kWh) at 350 km/h. Fig. 15 Open in new tabDownload slide CRH-0207 per capita consumption over 100 km on a flat road Fig. 16 Open in new tabDownload slide CRH-0503 per capita consumption over 100 km on a flat road (iii) Emissions In order to protect the environment along the railway line, high-speed trains use advanced trash collection and sewage-collection devices. Trains can also be equipped with a refuse-collection system, using compression technology to compact a large amount of refuse. When the train arrives at a station, it carries out suction and refuse-collection operations as required. High-speed trains can thus achieve zero discharge along the line and facilitate centralized treatment of waste. (iv) Land saving Land is a non-renewable resource. The construction of high-speed railways must implement the principle of land saving, and adopt measures such as bridges, roads, and double-story and multi-storey buildings. Comparing the Beijing–Shanghai high-speed railway and the older Beijing–Shanghai line, the latter uses 14 969 hectares of land while the former uses 4081 hectares, saving 72.7% of land. However, the land-saving potential of the high-speed railway needs to be developed further. (v) Material saving The focus of material saving is on improving structural durability. The mandatory design life of the main structure, comprising subgrades, bridges, tunnels and ballastless tracks, is 100 years. It is estimated that the high-speed railway currently in operation is capable of meeting these design requirements for its structural service life. Structural durability involves considering not only the safety and life-cycle costs of the high-speed railway network, but also materials, energy consumption and construction waste disposal. The longer the service life, the greater the material, water and energy savings. The development of weather-resistant steel and durable polymer materials for the production of concrete with a life cycle of 150 years and above is urgently needed. (vi) Greenification The China railway has requested that the railway network be developed as a green space. The high-speed railway lines and ordinary lines have been greenified and beautified according to this principle, although greenification technology for desert and rocky areas remains underdeveloped. 3. Conclusions and implications The following conclusions can be drawn from this analysis of the various indicators for evaluating the improvements in the speed of the current high-speed railway network from 350 km/h to 400–420 km/h (see Fig. 17): Fig. 17 Open in new tabDownload slide Analysis of key test techniques and indicators for increasing the speed of the high-speed railway network (i) The majority of safety indicators are in an excellent condition, with only the wheel load shedding rate exceeding the standard, without affecting safety. The system is therefore reliable. The four key technologies also fall within the excellent level of the safety indicators, that is, in the case of existing technical facilities, speed increases to 400–420 km/h can ensure safety. (ii) Comfort levels deteriorate as speed increases. Although there is no indoor noise standard for speeds of 400–420 km/h, the study indicates that the current indoor noise standard for 300–350 km/h is adequate for human comfort. If the noise increases beyond this level, passengers are likely to feel uncomfortable, especially on long-distance trips, and the indoor noise level would therefore be considered unacceptable. The microbarometric wave change and electromagnetic radiation values meet the standard, while vehicle stability is close to the limit, but acceptable. (iii) The realization of intelligent systems is a gradual process. At present, online ticketing, the facial-recognition system, comprehensive Wi-Fi coverage and the card system in operation on certain lines have achieved a high degree of awareness and a high level of satisfaction from passengers. These intelligent components will remain usable if speeds are improved. Other indicators cannot be realized immediately; however, these do not affect the speed-improvement efforts. (iv) Regarding environmental protection, or green indicators, the impact of noise on the environment is too high and is unacceptable. Energy consumption is proportional to the square of the speed; at 420 km/h, for example, consumption is 44% higher than at 350 km/h, which is unacceptable [12]. CO2 emissions from the high-speed railway network is reflected in power plant emissions, and is directly proportional to energy consumption. The land-saving and greenification indicators and measures meet current requirements. Improvement in the durability index is a gradual process, but this does not affect the speed-improvement efforts. As far as the current level of infrastructure and equipment technology is concerned, the main obstacles to increasing high-speed railway speeds to 400 km/h and above are energy consumption and noise. To solve these problems, three areas need to be addressed: (i) development of a new track-based foundation to increase elasticity and reduce vibration noise; (ii) research on the structure and arrangement of new sound barriers, able to absorb and block part of the running noise of trains from the outside in order to reduce the impact on the surrounding environment; and (iii) development of a new EMU, focused on reducing running air resistance and thus saving energy and reducing noise. These three areas have sufficient research foundation, and further technical research is needed to refine the key technologies involved in increasing high-speed railway speeds. It is clear that technical standards for high-speed railway networks with speeds of 400 km/h and above are the basis for further speed improvements and should be developed. Conflict of interest statement. None declared. References [1] Transportation Division of the National Development and Reform Commission . 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Innovation and practice for engineering quality management of high speed railway in China . China Railway Science 2015 ; 36 : 1 – 10 . Google Scholar OpenURL Placeholder Text WorldCat [7] C L . China High Speed Railway Dynamic Acceptance. In: Beijing: China Railway Publishing House , 2014 . [8] Wang K . Study on performance matching of wheel-rail dynamic interaction on curved track of speed-raised and high-speed railways . Ph.D. Thesis. Southwest Jiaotong University 2013 . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC [9] K W , W Z. Study on performance matching of wheel-rail dynamic interaction on curved track of speed-raised and high-speed railways . China Railway Science 2014 ; 35 : 142 – 144 . Google Scholar OpenURL Placeholder Text WorldCat [10] C L . Research on the management innovation and practice of construction for Beijing-Shanghai high speed railway . Journal of Railway Engineering Society 2014 ; 9 : 1 – 7 . Google Scholar OpenURL Placeholder Text WorldCat [11] Liu B. Review and revelation of railway signal and railway speed-up development . Railway Operation Technology 2014 ; 20 : 4 – 7 . [12] C L . High-Speed Railway Construction Project Engineering Quality Management. In: Beijing: China Railway Publishing House , 2016 . © The Author(s) 2019. Published by Oxford University Press on behalf of Central South University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. © The Author(s) 2019. Published by Oxford University Press on behalf of Central South University Press.
TI - A discussion on technologies for improving the operational speed of high-speed railway networks
JF - Transport Safety and Environment
DO - 10.1093/tse/tdz003
DA - 2019-07-01
UR - https://www.deepdyve.com/lp/oxford-university-press/a-discussion-on-technologies-for-improving-the-operational-speed-of-MKN3UfGdjn
SP - 22
EP - 36
VL - 1
IS - 1
DP - DeepDyve
ER -