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[Objective] To enable the through train operation between Suzhou Rail Transit Line 11 and Line 3, a customized signaling system upgrade solution is required based on the unique characteristics and operational demands of the lines, aiming to achieve the technical goals of one line, one plan [Method] The key technical points in upgrading the urban rail transit signaling system to driverless operation mode are analyzed. The signaling system upgrade plan for Suzhou Rail Transit Line 11 and Line 3 through train operation is examined, with a focus on the technical challenges and innovations in station renovation, control center integration, and network compatibility. [Result & Conclusion] Suzhou Rail Transit Line 3 is the first in China to upgrade from GOA2 (semi-automated train operation) to GOA4 (fully automated train operation). After the signaling system upgrade is completed, Line 3 operates more safely, efficiently, and intelligently, while ensuring full compatibility and seamless integration between the signaling systems of Line 11 and Line 3. [ABSTRACT FROM AUTHOR]

[Objective] When urban rail transit signaling systems reach their lifespan end, the aging signaling equipment must be upgrade and renovated. The PSD (platform screen door) interface is a crucial part in signaling system upgrade. Since the renovation cycles of PSD and signaling system are not synchronized, it is essential to develop a PSD interface solution during the signaling system upgrade to ensure compatibility between the new signaling system and the existing PSD, while maintaining the interface functionality between them during the transition process of signaling system upgrade. [Method] The adaptation of the new signaling system to existing PSD interface and the PSD reverse connection scheme between new and old signaling systems are key challenges in the signaling system renovation process. Based on the PSD interface solution of a specific signaling system upgrade project in China, the interface functions between the signaling system and PSD are explained, the interface time sequence of signaling system control commands using pulse and continuous signal methods separately is analyzed. Considering the characteristics of existing PSD interface circuit and new signaling system, a modification method for existing PSD interface circuit renovation is proposed, allowing the new signaling system to be compatible with the existing PSD interface. A reverse connection scheme for PSD interface is also designed to ensure a smooth transition between the new and old signaling systems. [Result & Conclusion] The proposed PSD interface solution in the signaling system upgrade and renovation ensures seamless transitions between the old/new signaling systems and PSD interfaces, while also improving the reliability of the PSD interface to some extent. [ABSTRACT FROM AUTHOR]

[Objective] Compared to the CBTC (communication-based train control) system, CTCS2+ ATO (Chinese train control system level 2 + automatic train operation) system requires longer usable track lengths due to its built-in protection zones, leading to increased construction investment for some underground turnout stations. Since city railways tend to have more underground stations, using the CTCS2 + ATO system can significantly raise civil engineering costs. To improve the economic efficiency of such projects, it is necessary to study a solution is needed to reduce the track usable length requirements for city railway turnout stations using the CTCS2 + ATO system. [Method] While maintaining the same safety protection distance, it is proposed to use virtual ground data to ensure accurate stopping positions and setting up continuation routes to shorten the effective track length at turnout stations. Key considerations for this solution, such as unlocking methods for continuation routes, signal placement, principles for configuring virtual data, safety guarantees during fault scenarios, and the setup of safety lines, are thoroughly analyzed. [Result & Conclusion] For unlocking continuation routes, a 'stop and unlock' method is recommended. At turnout stations with side tracks, it is suggested to install safety lines in the track forward direction instead of the reverse direction to improve the operational efficiency. For city railway turnout stations, the proposed continuation route solution can reduce the distance between the platform end and the basic track joint in front of the turnout from 70 m to 25 m. This can significantly reduce the scale of underground stations, lower civil engineering costs, and improve the project overall economic efficiency. [ABSTRACT FROM AUTHOR]

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

［Objective］When urban rail transit signaling systems reach their lifespan end, the aging signaling equipment must be upgrade and renovated. The PSD (platform screen door) interface is a crucial part in signaling system upgrade. Since the renovation cycles of PSD and signaling system are not synchronized, it is essential to develop a PSD interface solution during the signaling system upgrade to ensure compatibility between the new signaling system and the existing PSD, while maintaining the interface functionality between them during the transition process of signaling system upgrade. ［Method］The adaptation of the new signaling system to existing PSD interface and the PSD reverse connection scheme between new and old signaling systems are key challenges in the signaling system renovation process. Based on the PSD interface solution of a specific signaling system upgrade project in China, the interface functions between the signaling system and PSD are explained, the interface time sequence of signaling system control commands using pulse and continuous signal methods separately is analyzed. Considering the characteristics of existing PSD interface circuit and new signaling system, a modification method for existing PSD interface circuit renovation is proposed, allowing the new signaling system to be compatible with the existing PSD interface. A reverse connection scheme for PSD interface is also designed to ensure a smooth transition between the new and old signaling systems. ［Result & Conclusion］The proposed PSD interface solution in the signaling system upgrade and renovation ensures seamless transitions between the old/new signaling systems and PSD interfaces, while also improving the reliability of the PSD interface to some extent.

［Objective］To enable the through train operation between Suzhou Rail Transit Line 11 and Line 3, a customized signaling system upgrade solution is required based on the unique characteristics and operational demands of the lines, aiming to achieve the technical goals of 'one line, one plan'. ［Method］The key technical points in upgrading the urban rail transit signaling system to driverless operation mode are analyzed. The signaling system upgrade plan for Suzhou Rail Transit Line 11 and Line 3 through train operation is examined, with a focus on the technical challenges and innovations in station renovation, control center integration, and network compatibility. ［Result & Conclusion］Suzhou Rail Transit Line 3 is the first in China to upgrade from GOA2 (semi-automated train operation) to GOA4 (fully automated train operation). After the signaling system upgrade is completed, Line 3 operates more safely, efficiently, and intelligently, while ensuring full compatibility and seamless integration between the signaling systems of Line 11 and Line 3.

［Objective］Compared to the CBTC (communication-based train control) system, CTCS2+ATO (Chinese train control system level 2 + automatic train operation) system requires longer usable track lengths due to its built-in protection zones, leading to increased construction investment for some underground turnout stations. Since city railways tend to have more underground stations, using the CTCS2+ATO system can significantly raise civil engineering costs. To improve the economic efficiency of such projects, it is necessary to study a solution is needed to reduce the track usable length requirements for city railway turnout stations using the CTCS2+ATO system. ［Method］While maintaining the same safety protection distance, it is proposed to use virtual ground data to ensure accurate stopping positions and setting up continuation routes to shorten the effective track length at turnout stations. Key considerations for this solution, such as unlocking methods for continuation routes, signal placement, principles for configuring virtual data, safety guarantees during fault scenarios, and the setup of safety lines, are thoroughly analyzed. ［Result & Conclusion］For unlocking continuation routes, a ′stop and unlock′ method is recommended. At turnout stations with side tracks, it is suggested to install safety lines in the track forward direction instead of the reverse direction to improve the operational efficiency. For city railway turnout stations, the proposed continuation route solution can reduce the distance between the platform end and the basic track joint in front of the turnout from 70 m to 25 m. This can significantly reduce the scale of underground stations, lower civil engineering costs, and improve the project overall economic efficiency.

Objective After the upgrade of Shanghai Rail Transit Lines 3 and 4 signaling systems, their functions are highly concentrated in the on-board train controller. In the event of on-board train controller failure leading to train degraded status, the operational capacity of the line will decrease significantly, requiring a safe and efficient withdrawal of degraded trains from service. Method The structural characteristics of TACS （train autonomous circumambulate system） equipment for Shanghai Rail Transit Lines 3 and 4 are presented, the operational scenarios for train degradation are analyzed, and the operation control methods applicable after train degradation based on equipment role are elaborated. Result & Conclusion After a train enters the degraded state, the wayside train controller will take over the resource management from trackside resource controller. Based on the operational tasks assigned by train scheduling, a back-up localization system is utilized to replace the on-board train manager for resource interaction with the trackside resource managers and other trains，with signal lights serving to direct train operation. This method maintains the tracking logic for train-to-train communication, and is suitable for line upgrades by avoiding to add equipment on trackside and reducing construction and maintenance costs.

Objective With the increase in data traffic and diversification of data types in urban rail transit signaling systems, higher demands are placed on reliability, real-time performance, and security. It is necessary to thoroughly investigate QoS (quality of service) strategies for wired communication networks in signaling system. Method Based on the actual data from signaling systems and the architecture of wired communication networks, an analysis is conducted on the service requirements of ATP (automatic train protection) and ATS (automatic train supervision) subsystem backbone networks in the signaling system, from perspectives of network bandwidth, bandwidth requirements of each service, and involved data terminals. Considering the transmission capacity, data processing efficiency, and fault tolerance of wired communication networks, an optimized QoS implementation strategy for the signaling system is proposed and tested to validate its effectiveness. Result & Conclusion The QoS strategy employs RSVP (resource reservation protocol) to reserve resources before establishing communication sessions, and configures appropriate DSCP (differentiated services code point) parameters to ensure controllable bandwidth usage for each service terminal. Priority processing of services on the backbone network switches is based on the IEEE 802.1p protocol. Simulation test results show that the QoS strategy effectively limits the traffic of individual terminals under extreme traffic conditions, preventing application unavailability caused by single terminal failure. This significantly improves the quality and performance of the signaling system, ensuring the safe and efficient operation of urban rail transit signaling systems.

Objective The control of PSD (platform screen doors) by signaling system is crucial for ensuring urban rail transit stable operation. The interface between the signaling system and the PSD system is equally important for the stable and efficient control of PSD. Therefore, it is necessary to conduct an in-depth analysis of this interface, comparing traditional relay interfaces with the new type of PSDC (platform screen door control) system interface, and to analyze the scheme of PSD direct control using PSDC interface. Method A detailed analysis of the system architecture using relay interfaces versus PSDC interface is provided. These interfaces are compared from equipment structure, information exchange, equipment maintenance, and operation-maintenance support perspectives. Based on the interface structures, the scheme of PSD direct control using PSDC interface is discussed. Result & Conclusion Compared to the relay interface, PSDC interface features faster communication speed, better security, and shorter information exchange process, presenting a comprehensive and intuitive display of equipment status and parameter changes with obvious advantages. The above-mentioned scheme reduces the need for intermediate devices to transmit the command and non-command information, facilitating centralized monitoring and management, and thereby enhancing operational efficiency.

Objective The signaling system of Shanghai Rail Transit Line 3 and Line 4 can no longer meet the requirements of high-density and high-reliability networked operation, necessitating an upgrade to TACS (train autonomous circumambulate system). Therefore, based on the working principle of TACS, it is essential to study a fully redundant on-board architecture for the signaling system. Method According to the working principle of TACS, the design scheme of fully redundant on-board architecture is elaborated. TACS hardware and communication network architecture based on fully redundant on-board architecture scheme is described, the fault handling mechanism is analyzed, and the results of dynamic and static functional tests as well as tests under different operation scenarios are examined. Relevant suggestions are proposed with analyzing the advantages and disadvantages of fully redundant on-board architecture. Result & Conclusion The fully redundant on-board architecture employs designs such as dual-machine hot standby, dual-channel redundancy, and dual-power redundancy, effectively enhancing the safety and stability of the signaling system, improving train intelligence level, thereby increasing line capacity, operation safety and flexibility.

Objective With the rapid development of urban rail transit, the operational volume of trains has significantly increased. The existing CBTC (communication-based train control) system can no longer meet the signaling system needs of high-density operations, necessitating the research into urban rail transit signaling system evolution scheme. Method An evolution scheme for urban rail transit signaling system is proposed, with transitioning from an up-down backup degradation operation mode to a left-right mutual backup redundancy mode in the event of single-point failures in signaling system. First, the ZC (zone controller) and CI (computer interlocking) systems are merged to decrease signaling system framework levels. Then, the ATS (automatic train supervision) system is improved to a hot standby redundancy structure for Ethernet heartbeat information exchange. Additionally, a highly redundant DCS (data communication system) architecture is designed to achieve physical isolation between core signal operations. Finally, the on-board signaling system is modified to a head-tail redundancy structure, enabling seamless switching between primary and backup modes. Result & Conclusion The proposed method significantly enhances the reliability and availability of the signaling system, ensuring seamless operations during failures, maintaining system stability and continuity under high-density operations.

Objective In the alternate day depot return operation mode, trains either stay overnight on the mainline or run continuously day and night. The relevant functions of existing urban rail transit signaling system can no longer meet the requirements, therefore needing an optimization. Method Starting with an analysis of the functional optimization needs of signaling system, the optimization scenarios and contents for the on-board ATC (automatic train control) subsystem, the trackside ATC subsystem, the ATS (automatic train supervision) subsystem, and the signaling equipment self-inspection/monitoring are elaborated in detail. Result & Conclusion For the alternate day depot return operation mode, the on-board ATC subsystem is enhanced with train position memory function, allowing overnight trains on the mainline to start directly upon powered on in the controlled mode of signaling system. By adjusting buffer zone settings, the convergence protection envelope is optimized for non-communication trains staying overnight on the mainline, to avoid impacting the operation of other mainline trains. The optimized ATS subsystem supports both the automatic schedule matching after online timetable changes and the cross-day operation schedules. The functional optimization of signaling equipment self-inspection work enables the extension of signaling system equipment self-inspection or reboot cycle, meeting the requirements for long-term continuous operation. The series of signaling system functional optimizations enhance the availability of signaling systems and improve the service levels.

Objective To improve the real-time, accuracy, and efficiency of information services, and enhance the operational service efficiency and quality of Shanghai rail transit, it is essential to optimize the interface content between the audio video unified information service system and the signaling system. Method Starting from the architecture and deficiencies of the interface content between the existing audio video unified information service and the signaling system of Shanghai Rail Transit, the requirements for interface content optimization and the architecture of the optimized interface content are sorted out. By incorporating typical operational scenarios, the optimized primary functions of interface content are discussed. Result & Conclusion By adopting a primary-backup redundant dual-link transmission architecture, the optimized interface content enhances both redundancy and security of the interface. When partial adjustments are needed during operations, using unified interface content to define terminal stations could eliminate the risk of broadcast errors. For FAO (fully automatic operation) scenarios, a first and last train marker function added in the interface content reduces the workload for manual updates, allowing the signaling and the audio video unified information service systems to adapt to adjustments in operation diagram automatically.

Objective Urban rail transit CBTC (communication-based train control) systems face complex and diverse cybersecurity challenges. Existing cybersecurity tools feature high false alarm rates and poor adaptation to CBTC systems, lacking in-depth analysis of business data and integration across multiple systems, thus uncapable to proactively detect cybersecurity threats. To enhance the cybersecurity operations of CBTC systems and ensure the continuity of CBTC system business operations, it is necessary to develop a cybersecurity situational awareness system applicable for urban rail transit CBTC systems. Method Based on general technical requirements outlined in relevant standards, a cybersecurity situational awareness system architecture tailored to urban rail transit CBTC systems is proposed. The data content from front-end data sources and the specific functions of core components in the system architecture is expounded. Key technologies, including log normalization techniques, security threat analysis methods, and situational visualization techniques for CBTC systems are introduced. Result & Conclusion The cybersecurity situational awareness system architecture applicable for urban rail transit CBTC system is highly compatible with CBTC system architecture, and its functions are deeply integrated with CBTC operational scenarios. The implementation of this system enables efficient business coordination, reduces the false alarm rates of existing cybersecurity equipment, enhances the cybersecurity levels of CBTC systems, effectively ensuring the continuity of CBTC system business operations.

Objective The maintenance and management of urban rail transit signaling systems encompass various tasks such as equipment monitoring, production organization, and information management, each task involving one or more business systems. These systems vary in construction ages and often have overlapping or redundant functions on the same railway line. Therefore, there is a need to develop a big data IOM (intelligent operation and maintenance) platform for signaling systems that integrates data and enables analytical functions. Method Based on the current state of signaling system maintenance operations and the characteristics of signaling system data, a signaling system big data IOM platform is constructed using a layered data approach to meet practical application needs. The overall architecture of the platform is introduced, the design scheme of its three sub-platforms: data sharing, data analysis, and data application, is expounded. Result & Conclusion The signaling system big data IOM platform is piloted on Zhengzhou Metro network, which achieves the aggregation and unified storage of data from various business systems, including the centralized signal monitoring system, construction management system, and material management system. It enables the correlation analysis of business data such as production plans, maintenance records, inspection issues, fault records, monitoring alarms, electrical characteristics, and equipment ledgers. Additionally, the platform regulates standardized data interfaces and multi-dimensional data applications, such as quantitative scoring of key signal equipment quality and key maintenance tasks. The application of this platform reduces data redundancy within the signaling system, simplifies the complexity of maintaining signal equipment information, enhances resource utilization, and improves the convenience for maintenance personnel in data reviewing.

Objective To facilitate the integration of passenger flow between Suzhou and Shanghai, Suzhou Rail Transit Line 3 and Line 11 are connected at Weiting Station, where passengers currently transfer via the concourse within the fare-paid zone, resulting in a restriction of the operational capacity for both Line 3 and Line 11. To meet the urgent need for capacity enhancement, a renovation plan of the signaling system for Line 3 and Line 11 through train operation is required. Method The existing conditions and technical differences between the signaling systems of Line 3 and Line 11 are analyzed. Based on different wireless communication standards, a signaling system renovation plan is proposed to meet the requirements of the through train operation between two lines. The implementation plan for the signaling system renovation is designed according to the project preparation schedule for Line 3 and Line 11 signaling system upgrade, focusing on modifications of the on-board signaling subsystem, ATS (automatic train supervision) subsystem, mainline station signaling subsystem, and depot signaling subsystem. Result & Conclusion Through adaptive modifications to the signaling systems of Line 3 and Line 11, train cross-line driverless operation is achieved, the compatibility and interchangeability of on-board ATC (automatic train control) equipment, ATS servers, and workstation hardware are implemented, allowing for uninterrupted automatic switching of vehicle-wayside wireless communication. Trains can operate seamlessly across Line 3 and Line 11 in FAO (fully automatic operation) mode, enhancing the operational efficiency of urban rail transit and improving the passenger travel experience.

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Signalling & Communication Engineering is the property of Railway Signalling & Communication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective Shanghai Metro Line 16 adopts a flexible marshalling operation mode, but it takes a long time for the train to complete the coupling and decoupling process, leading to great difficulty in train operation organization. In order to further improve the operation efficiency and simplify the train operation organization, an in-station coupling and decoupling scheme is put forward. Method Based on Shanghai Metro Line 16, the problems that need be solved for train in-station coupling and decoupling are analyzed. In view of the above problems, a concrete implementation scheme for the train in-station coupling and decoupling is put forward. Several tests are carried out on Shanghai Metro Line 16 to verify the effectiveness of the scheme. The main rules about operation safety specified in "Specification on train coupling and decoupling in Longyang Road Station of Shanghai Metro Line 16" are introduced. Result & Conclusion Longyang Road Station, a terminal turnaround station with minimal impact on the line operation, is selected for the coupling and decoupling site. The function of coupling and decoupling operation in the station is realized through modifying the ATS software chain logic and defining a special parking area in the station for coupling and decoupling operation. The test results verify the safety and feasibility of the scheme.

Objective City (suburban) railways are a weak link in the four-network integrated development of rail transit system in China. There is currently no unified understanding regarding their functional positioning and passenger flow demands. This lack of consensus leads to difficulties and issues in selecting formats for city (suburban) railway signaling system, calling for in-depth research. Method By elucidating the integration and operation requirements of city (suburban) railways in a multi-level rail transit system, the problems existing in operation management and equipment type selection are analyzed. Using the Wuxi-Yixing Intercity Rail Transit project as a study case, the characteristics of China Railway CTCS-2 (China Train Control System level 2)+ATO (automatic train operation) system and the urban rail CBTC (communication-based train control) system are compared. The adaptability of these systems in city (suburban) railways is analyzed. Based on the demand for cross-line operation with Suzhou-Wuxi-Changzhou intercity railways, the signaling system design scheme for Wuxi-Yixing Intercity Rail Transit is investigated. Result & Conclusion The signaling system scheme based on CBTC system, with compatibility for CTCS-2+ATO system is suitable for the case line. This scheme ensures the city (suburban) railways capabilities for mass-transit type operation and a high level of automation, but also meeting the compatibility requirements for the signaling system when trains operating across lines to national railways.

[Objective] The current calculation of safety distance in the moving block signaling system does not consider adverse working conditions such as faults and low adhesion coefficients, resulting in poor authenticity and low precision in safety distance calculations. It is necessary to study the impact of the aforementioned adverse conditions on the safety distance of train signaling systems. [Method] A safety distance model for the signaling system is established to analyze the main factors affecting train safety distance. Considering train braking systems, longitudinal dynamics, and wheel-rail adhesion conditions, MATLAB/Simulink software is used to build a simulation platform encompassing stages such as on-board ATP (automatic train protection) trigger emergency braking, traction cut-off, coasting, emergency braking establishment, and emergency braking. Combining actual train parameters and relevant standards, simulation studies on the safety distance of signaling systems under conditions of ultra-low adhesion, partial loss of braking force in some vehicles, and different train operating speeds are conducted. [Result & Conclusion] Emergency stopping distance is the key factor affecting the safety distance of signaling system and is related to wheel-rail adhesion conditions, the line maximum allowable operating speed, and potential fault types. Under normal conditions with an adhesion coefficient of 0.03 and a train speed of 120 km/h, the safe distance is 1 520.7 m. In the most unfavorable condition (a faulty heavy-loaded vehicle with other vehicles unloaded, 2 bogies removed), the corresponding safety distance is 2 196.7 m. In practical applications, speed measurement errors and positional uncertainties should be taken into account to leave a certain margin for signaling system safe distance and ensuring train operation safety.

[Objective] With the theme of promoting urban rail transit information, developing intelligent system, and building 'smart urban rail' for a highly integrated urban rail transit cloud platform is the direction of technological development in the new era. The integration of signaling system and cloud platform is an important development trend of signaling systems. In-depth research is needed on how to build an efficient, reliable, and cost-effective signaling system based on cloud architecture. [Method] Combining the needs of Changzhou Metro new round of urban rail transit construction scheme, based on the technological characteristics of existing cloud platform and current situation of signaling system, the feasibility and construction scheme of signaling system cloudification are analyzed and verified. The research of contents such as line network unified ATS (automatic train supervision) construction scheme, signaling system cloudification scope, cloud platform architecture selection, and signaling system ATS interoperability scheme after cloudification are emphasized. [Result & Conclusion] The definition of signaling system cloudification is clarified, discussing the feasibility of signaling system ATS cloudification. According to the estimation whether the signaling system can pass SIL2 (safety, integrity level 2) after cloudification, a list of specific equipment for ATS cloudification is determined. The new-generation signaling system construction scheme based on cloud architecture is proposed, and the urban rail transit cloud platform architecture carrying ATS is suggested to transit from mode 1 to mode 3 gradually, possessing the ability to update and iterate. Signaling system equipment can level up the processing capacity of the signaling system and reduce hardware device amount after integration into cloud platform, contributing to realizing line network resource/information exchange and promoting modulating the development of intelligent scheduling.

[Objective] During the system commissioning, train debugging and trial operation on Chengdu Metro Line 18, the axle counting equipment exhibits AIO (abnormal interference and occupation) due to various disturbances in different scenarios, significantly affecting metro operation safety. Therefore, it is necessary to analyze and conduct tests and experiments on various abnormal disturbance scenarios to select appropriate improvement schemes for resolving the issue of AIO in axle counting equipment. [Method] The AIO situations in the axle counting sections of the vehicle depot, in the axle counting section when train passes through phase division zones, and in the axle counting section during catenary power-off are introduced. Various scenarios of AIO in the axle counting equipment are analyzed, and relevant investigations, tests, and verifications are performed. Finally, solution schemes for different disturbance scenarios are proposed. [Result & Conclusion] For the AIO scenario in the axle counting section of the vehicle depot , the scheme of adding equalizing lines on the inner side of the front garage, and on track A and track B sides in the depot, along with the use of a new amplification board, can solve the problem. For the scenario of AIO in the axle counting section when train passes through phase division zones, the schemes of isolating interference, eliminating or weakening interference intensity can be implemented for the problem. For the scenario of AIO in the axle counting section during catenary power-off, the scheme of optimizing system grounding can solve the problem, where the weak flat steel is disconnected from the traction return path (rail), and then connected to station grounding grid, along with adaptive optimization of the parameters for the axle counting channel lightning protection module.

[Objective] Time synchronization is the foundation for ensuring the coordinated linkage of sub-systems within the signaling system, which directly affects the punctuality and operational safety of trains, serving as the basis for achieving train FAO (fully automatic operation). Therefore, it is necessary to study the train FAO signaling system synchronization scheme. [Method] The role of time synchronization devices in the signaling system is introduced. A time synchronization scheme is proposed and explanation is provided for the scheme. [Result & Conclusion] The proposed time synchronization scheme is as follows: the communication front-end processer of the signaling system obtains a unified time source from the clock system through the network, and time services are provided only by the host of the communication front-end processer. The application server as the host of client synchronizing with the communication front-end processer, and only the application server host is used as the server to provide time services to the lower-level devices. The gateway server and various terminal devices synchronize with the time of the application server host, with the gateway server host serving as the clock source to provide time services to the lower-level devices. The ATC (automatic train control) on-board devices and DCS (data communication sub-system) devices serve as clients to synchronize the gateway server host time. The proposed scheme utilizes different synchronization methods for the internal and external environments of the signaling system, avoiding internal signaling system jumps caused by external clock jumps, ensuring the time synchronization accuracy of the equipment. The time synchronization accuracy can reach millisecond level, thereby guaranteeing the requirements for train FAO.

Purpose – In the continuous development of high-speed railways, ensuring the safety of the operation control system is crucial. Electromagnetic interference (EMI) faults in signaling equipment may cause transportation interruptions, delays and even threaten the safety of train operations. Exploring the impact of disturbances on signaling equipment and establishing evaluation methods for the correlation between EMI and safety is urgently needed. Design/methodology/approach – This paper elaborates on the necessity and significance of studying the impact of EMI as an unavoidable and widespread risk factor in the external environment of high-speed railway operations and continuous development. The current status of research methods and achievements from the perspectives of standard systems, reliability analysis and safety assessment are examined layer by layer. Additionally, it provides prospects for innovative ideas for exploring the quantitative correlation between EMI and signaling safety. Findings – Despite certain innovative achievements in both domestic and international standard systems and related research for ensuring and evaluating railway signaling safety, there’s a lack of quantitative and strategic research on the degradation of safety performance in signaling equipment due to EMI. A quantitative correlation between EMI and safety has yet to be established. On this basis, this paper proposes considerations for research methods pertaining to the correlation between EMI and safety. Originality/value – This paper overviews a series of methods and outcomes derived from domestic and international studies regarding railway signaling safety, encompassing standard systems, reliability analysis and safety assessment. Recognizing the necessity for quantitatively describing and predicting the impact of EMI on high-speed railway signaling safety, an innovative approach using risk assessment techniques as a bridge to establish the correlation between EMI and signaling safety is proposed.

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Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Considering the line characteristics and actual situation of Lijiang Rail Transit Line 1, this paper studies and analyzes the control schemes of signaling systems at level crossings of modern trams. The structure, functions and interfaces of the level crossing control system and the level crossing signal equipment layout design of Line 1 are described in detail, and the whole process of trams passing through level crossings is deeply analyzed. By focusing on different types of level crossings, and through the equipment layout and interaction between tram level-crossing control system and municipal traffic control system, trams are able to pass through the level crossings safely and efficiently. This paper puts forward a solution for the scenario where there are several types of level crossings on the same tram line and explains the different processing logic for trams passing through different types of level crossings to fully guarantee the safety and operation efficiency of trams. [ABSTRACT FROM AUTHOR]

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Urban Mass Transit is the property of Urban Mass Transit Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

According to the network and public transportation characteristics of the metropolitan area rails, the technical goal of integration of signaling systems is proposed, which is, the integration of existing C2/C2+ATO and CBTC systems and the integration of signaling systems using new interconnection technology. Based on the analysis of differences in technical level, working mechanism and system function between the ground and vehicle equipment of the existing mainstream CTCS and CBTC systems, the interconnection schemes of "ground-to-vehicle compatibility" and "vehicle-to-ground compatibility" are proposed. Combined with the current researches of relevant manufacturers, the new interconnection technology route of suburban railway is analyzed. [ABSTRACT FROM AUTHOR]

This paper studies the specific schemes and steps of adding three grades of protection to LTE system carrying signal services based on Xi'an Metro Line 14. Two feasible access schemes of grading protection are proposed according to the characteristics of Line 14, and the optimal grading protection access scheme is selected through network architecture and performance evaluation and comparison to ensure the security and stability of network transmission. At the same time, through the description of the relevant interface configuration and precautions of the grading protection system, the important steps in the process of adding grading protection to LTE system involving the safety of train operation are elaborated to ensure network security, provide important guarantee for traffic control of rail transit signaling system, and provide reference value for subsequent rail transit grading protection access. [ABSTRACT FROM AUTHOR]

In this paper, the necessity of reservation for extension in urban rail transit construction is analyzed. Based on the key factors of reservation design for extension in urban rail transit signaling system, the reservation design scheme for extension in urban rail transit signaling system is elaborated from the points of trackside equipment, cabinet board, system design, data production, backbone network, temporary operational control center, etc. to improve the convenience and safety in connecting the extended line signaling system with the first phase signaling system. [ABSTRACT FROM AUTHOR]

Hangzhou Metro Line 1 is a Y-shaped line, it's Linping branch line is planned to be splitted off and placed under the control of metro line 9. In order to ensure the splitting and transformation of Linping branch line signaling system safely and efficiently, this paper studies and analyzes the splitting and transformation objectives, switching schemes and key technologies, and creatively puts forward the old and new systems switching scheme with the switching cabinet and the junction box, which provides ideas for the subsequent planned splitting and transformation of rail transit lines, and has certain reference value. [ABSTRACT FROM AUTHOR]

As the urban rail transit signaling systems of some subway lines have been in service for nearly 15 years, there is an urgent need to retrofit such signaling systems. The traditional retrofitting solution has such problems as huge construction difficulties, long construction period, large amount of involved equipment. Thanks to technical development, it is possible to reduce the retrofitting costs of signaling systems. The paper provides a phased retrofitting solution, which can not only reduce the costs and increase the efficiency, but also eliminate as soon as the negative impacts of the failure rate of existing onboard equipment on subway operation. [ABSTRACT FROM AUTHOR]