Analysis and Examination in wayside equipment failures of High speed line Train control system Yong-Kyu KIM 1, Jong-Hyun BAEK 1, Yong-Ki YOON 1, and Ducko SHIN 1 1 Train Control Research Team, Signaling & Electrical Engineering Department, Korea Railroad Research Institute, Uiwang city, Gyounggi do, Korea Abstract Ever since Kyung Bu High Speed Railway was open in 2004, delay error has been occurred often due to problems found in turnout or HBD on Track side. Those errors arouse the necessity to perform overall review on equipment's reliability and its own functionality. In this paper, therefore, we measure the vibration generated at the very moment of train passing on track-side equipments to find out an error cause. We also analyze and review the measuring results in order to find out the methods that ensure the accurate function and operation of the track-side equipment. 1. Introduction As high speed train begins running with 300km/h in Korea, there have been various track-side equipment related problems occurred in the form of an early stage of system stabilization. Indeed, there were several errors occurred on the turnout installed at Chil-Gok IEC(Interlocking Equipment Center), 170km south of Seoul, in 2005 and those occurred repetitively in spite of several replace activities[1,2]. To make the matter worse is similar errors were found on HBD(Hot Box Detector) installed near signal room area[3], so it became unavoidable to review not only equipment's reliability but also functional problems related to track-side equipment. In this paper, therefore, we investigate, analyze and review the causing factors of track-side equipment related errors in terms of high speed operation and maintenance. The main objective of these activities is to suggest acceptable plans for which implement reliable operation and maintenance for high speed track-side equipments. In order to determine track-side equipment related problems precisely, we performed material test for error found equipments. Also, we carried out field research to identify error occurred environment. Finally, we analyzed abnormal symptoms of before and after error occurrence via some reports documented in CTC(Centralized Traffic Control) CAMS(Computer Aided Maintenance Sub-System), installed at Gwang-Myung Station for high speed line monitoring to figure out actual problems caused when high speed train passing. From these activities above, we concluded that major cause of track-side equipment related error is originated from track-side environment. Especially, we paid attention to the fact that the error, repetitively occurred on turnout when KTX is passing, has been stopped after track configuration maintenance and so has the HBD. We also confirmed that the error tends to occur at the very moment of KTX passing. In this paper, therefore, we examine the vibration related regulations on track-side equipment, measure the vibration generated on error occurred equipments and analyze all results[4]. 2. Basic Test The basic test is aimed for turnout and HBD which are track-side equipments that frequent errors are found. In the case of crank frame, a component of turnout controlling train's direction, it has been broken repeatedly in spite of several replacements. Since the cause of failure has not been clarified, we assumed the possible factors as follows, in order to prevent the error from reoccurring; - Manufacturing defect - Impact on crank frame generated by obstruction passing
- Poor track installation: leading to destructive vibration when a train is passing First, we decided to examine the material related problems. Generally, turnout is made of rolled steel for general structure, SS 400(Fy=2.4t/ cm2 ), one of the most representative steel used for bridge construction, industrial machinery, construction site and offshore structure. Especially, the material is known for its ability to withstand against modification since it has high homogeneity and great strength/toughness; in addition, it is suitable for compression and tensile. The strength level of rolled steel for general structure can be classified into several groups. General strength of SS 400 is 60 kgf/ mm2 and other characteristics are given in Table 1[1]. a) Installation Location b) Example of Broken Bell Crank Figure 1: Error Occurred Turnout Type Use C Mn P S SS400 Steel Plates, Flats, Bars, 0.050 0.050 - - SS490 Shapes and Straps Max Max Table 1: Type of SS400 and Material Characteristics As for material test, we disassembled crank support into Body-A and Neck-B as shown in Figure 2, then examined related components. National standards KS D 3503:1998(SS400) and KS D 1652:2001 are applied as for test standards, and Spark Emission Spectrophtometer (Higher Analytical) is used as a test tool. a) Test simple b) Body-A c) Neck-B Figure 2: Configuration of Bell Crank support Element P S Fe C Si Mn Cr Standard 0.050 Max 0.050 Max - - - - - Body-A 0.004 0.014 93.0 5.39 1.03 0.26 0.01 Neck-B 0.006 0.017 94.2 3.87 1.39 0.30 0.02 Table 2: Reference Standards and Material Testing Results We checked that Body-A and Neck-B satisfied the component standards of bell crank support. Material characteristics and measuring results are given in Table 2. From the results above, we
confirmed that material is not the one to cause bell crank support breaking on turnout at Chil- Gok IEC. Consequently, we assumed other factors, such as vibration, may produce bell crank support breaking. Following assumptions were made based on turnout related error records in CTC maintenance system and expert's judgment. General problems due to obstruction were checked via obstruction detector. What is noteworthy, however, is that there was remarkable increasing in the number of error occurrence on detector for a month, from June 2005 to July 2005. On July 17 2005, the day crank support was broken, particularly, more failures were detected whenever KTX was passing. We also performed visual field inspection on HBD equipped near Chil-GoK signal room area, but no abnormal signs on installation environment were found. Accordingly, we reviewed the effect of vibration on HBD and HBD installation method in order to analyze the cause of error occurrence. As for HBD installation method review, we analyzed how to install HBD sensor into special sleeper made of cement based on manufacturer provided data. HBD infrared sensor, used to measure wheel axle temperature on Kyung Bu high speed railroad (Seoul - DaeGu), is equipped as shown in Figure 3 by using special structure. This installation method ensures continuous contact between the wheel and rail and keeps calibration stability acceptable at static sate. If there is horizontal acceleration, however, HBD weight(15kg) and support can not provide enough relative flexibility so that detection sensor can not detect wheel axle temperature properly or failures can be occurred. We also confirmed that it is necessary to disassemble the error occurred equipment thoroughly and then perform adjustment when performing track maintenance with tools. Figure 3: Example of Hot Box Detector Installation 2. Regulation on vibration While researching various data to identify vibration standards for track-side equipments, we found out that there exists no vibration related standards at all. Yet there is no exact reference on vibration standards in ERTMS/ETCS Environmental Requirements, proceeded in Europe, even though Cenelec Standard EN 50125, EN 50155 and ORE research paper A 118 report No 4 are applied, instead, only vibration test criteria and aseismicity are regulated. As for alternative vibration standards of track-side equipment, following standards, which are against random vibration having power spectral density, are given as Figure 4. These values represent vibration durability on track-side equipments; however, we also confirmed that these values are not exact enough to be used as vibration standards[1]. Installed on Rail Installed on Sleeper Installed on Ballast Installed on track-side Vertical 28.0g 13.0g 1.0g 0.23g Traversal 14.0g 5.0g 1.0g 0.23g Longitudinal 5.0g 2.0g 1.0g 0.23g Table 4: Vibration Limit according to Installation Location
a) Installed on Rail b) Installed on Sleeper c) Installed on Ballast d) Installed on track-side Figure 4: ERTMS/ETCS Regulations on Vibration for Signal Equipment 3. Vibration measurement In order to measure the vibration on track on which turnout and HBD installed, we performed some preliminary activities, such as adjusting measuring point and checking the soundness of measured values at measuring point, at night when few trains are running. Then, we performed vibration measurement as follows during day times when frequent train running is guaranteed. - Date: 9th May, 2006. AM 10:00 ~ PM 13:00 - Location: Chil Gok IEC - Measuring Equipment: DAQ: DEWE - 3010 (Dewetron, Austria) a) Sensor Installation b) Acceleration Sensor Installation Figure 5; Sensor Installation on Turnout Figure 6: Sensor Installation on HBD We mounted acceleration sensor on turnout as shown in Figure 5 so as to compare vibration acceleration on each sensor[2]. The location of each sensor is as follows; the end of " ㄱ shaped bell crank (1), on support (2), and on fixed point to sleeper (3). Then, we measured vibration acceleration vertical direction (Z direction). As for HBD, we mounted the acceleration sensor as illustrated in Figure 6, the upper side of HBD, both right and left, then we set train
direction as X, horizontal direction as Y and vertical direction as Z[3]. Acceptable measurement range of each mounted sensor is given as 2g for "X" direction, 2g for "Y" direction and 10g for "Z" direction. 4. Measuring results Figure 7: Data Acquisition Device Checking We have performed vibration measurement 4 times for turnout and HBD respectively. As for resulting values of turnout, the fixed point (3) has the lowest value, and the farther from the fixed point the greater the value; in addition, relating frequency analysis results show that the maximum frequency is approximately 45.7~49.7 Hz. The maximum, minimum values and relating maximum frequency of 4th time measurement are given in Table 5[4]. a) Vibration Acceleration Results b) Frequency Analysis Results Figure 8: Vibration Measurement on Turnout Number of Times 1st 2nd 3rd 4th Time 12:03:15 12:16:00 12:19:47 12:44:21 Location g(max) g(min) f(max) g(max) g(min) g(max) g(min) g(max) g(min) 1 9.515g -7.827g 49.7Hz 10.827g -10.067g 9.735g -7.832g 8.802g -7.944g 2 5.481g -7.963g 45.7Hz 10.110g -8.205g 6.133g -7.197g 5.803g -7.369g 3 5.573g -8.426g 45.7Hz 4.797g -6.165g 3.704g -5.261g 5.546g -5.603g Table 5: Vibration Acceleration on Turnout Figure 9 shows the resulting vibration acceleration of three directions (X, Y and Z) on HBD, both right side(r) and left side(l). It represents that greater vibration is measured on right side rather than left side. Especially, vibration of Z-direction has the greatest value while that of X-direction has the smallest. In addition, maximum vibration acceleration is measured on the right side in Z
direction (V_z_r). Given frequency components also represent the maximum value on the right side, at 21.0Hz for the right side and 25.0~29.2Hz for the left side specifically. a) Vibration Acceleration Testing Results b) Frequency Analysis Results Figure 9: Vibration Measurement on HBD No. of times 1st 2nd 3rd 4th Time 10:21:51 10:55:09 11:13:30 11:22:43 Location g(max) g(min) f(max) g(max) g(min) g(max) g(min) g(max) g(min) x 0.356g -0.279g 21.0Hz 0.337g -0.281g 0.331g -0.255g 0.291g -0.285g Right y 0.918g -0.973g 21.0Hz 0.876g -0.890g 0.912g -0.834g 0.889g -0.889g z 3.238g -2.241g 21.0Hz 2.524g -2.198g 2.954g -2.059g 3.122g -2.651g x 0.098g -0.128g 29.2Hz 0.106g -0.105g 0.132g -0.136g 0.157g -0.150g Left y 0.440g -0.419g 25.0Hz 0.545g -0.419g 0.488g -0.373g 0.426g -0.377g z 1.347g -1.120g 29.2Hz 1.015g -1.038g 1.365g -1.428g 2.261g -1.962g 5. Results Analysis and Suggestion Table 6: HBD Vibration Acceleration Throughout the process, it is proved that there is a close relation between vibration and failure. Generally, the vibration on the failure occurred point is abnormally high. Since there exists no standards on vibration, however, there have always been lots of controversy among the teams in charge of facilities on the responsibility for vibration related failure; in addition, existing vibration measurement is done on a train using track inspection car, rather than on track-side where frequent failures are occurred. Consequently, following activities should be done as preventive maintenance[5]; - Perform periodic vibration measurement where vibration-related failures are predicted to occur and predict vibration limits for related facilities by calibrating vibration before/after failures. - Establish the standards for preventive maintenance by analyzing measurement results. By doing so we may prevent a failure via asking facility management team to check the facilities when vibration measurements exceed the standards. - Compare the vibration measured on track-side with the one measured on inspection car by facility management team and analyze the results so as to set up the vibration standards for track-side. For this activity, it is necessary to collect measurement data obtained from both on track-side and on a train and analyze those data. When it comes to HBD which is highly sensitive to vibration, France Railroad tries to prevent vibration-related failures by fixing support to the upper side of PC sleeper in a way of support
installation to the lower side of existing rail. Therefore, it is recommended to mount HBD sensor to special sleeper, if possible, based on the fact that; - A sleeper should be less sensitive to a vertical movement so as to prevent adjustment error. - HBD including protective plate makes it easy to disassemble and perform track activities by using only two special sleepers, instead of 5 sleepers, when mounting HBD actually. - Simple readjustment and passing detector(d50) arrangement should be ensured after track maintenance. Conclusion In this paper, we tried to examine the failure cause of track-side equipments via field research, CAMZ (Computer Aided Maintenance Sus-System) and vibration calibration. From all these activities, we concluded that vibration is the main factor to cause failures. However, we found that vibration-related failures always trigger the controversy on its failure cause among facility management teams since there is no vibration standards that allow vibration measurements on track-side to be compared. In addition, we noticed that vibration measurement is usually done on a train using inspection car, rather than on track-side where frequent failures are found; in other words, track-side vibration and its effect have not been reviewed directly. As a result, we concluded that various studies on following activities should be carried out as a preventive maintenance in order to operate HSR TCS safely. First, perform vibration measurement where vibration-related failures are predicted to occur as a periodic maintenance and predict vibration limits for related facilities by analyzing vibration measurements before/after failures. By doing these, it is expected to make it possible to establish the preventive maintenance standards on track-side equipments. In addition, we may prevent any failures by asking facility management teams to check the facilities having failure potentials when measured vibration goes beyond the standards. Secondly, perform an investigation and analysis on correlation between the vibration measured on a train using inspection car and track-side vibration so as to predict rolling stock vibration standards towards track-side equipments. For these activities, it is necessary to collect measurement data obtained from both on track-side and on a train and analyze those data. References [1] Research Report on Performance and Safety Investigation for HSR TCS Stabilization, KRRI, 2005 [2] Y,K,KIM, J,H,BAEK, and J,K,KIM, Analysis On Causes of Faults in Damaged Bell Crank of High Speed Line Turnout, Korean Institute of Electrical Engineers, Summer Conference, May 2007 [3] Y,K,KIM, J,H,BAEK, and J,K,KIM, Analysis on causes of Faults in Hot Box Detector, Korean Institute of Electrical Engineers, Summer Conference, July, 2007 [4] Research Report on HSR Signal Stabilization and Performance Improvement, KRRI, 2006 [5] Research Report on Maintenance Plan for HSR Signal System Stabilization, KRRI, 2007