Chapter 20: Automatic Block Signalling PDF

Chapter 20: Automatic Block Signalling Section 1: Automatic Signalling - General 20.1.1 Automatic Block System on Double Line/Single Line: General (a) Automatic Block is a system in which the movement of trains is controlled by Stop Signals which are op...

Chapter 20: Automatic Block Signalling Section 1: Automatic Signalling - General 20.1.1 Automatic Block System on Double Line/Single Line: General (a) Automatic Block is a system in which the movement of trains is controlled by Stop Signals which are operated automatically by the passage of trains past the Signals. (b) The automatic Stop Signal which governs entry of Train into an Automatic Signalling section is a multiple aspect colour light signal which is not dependent upon manual operation but is controlled automatically by the passage of a train into, through and out of the Automatic Signalling section which the Signal governs. (c) The line between two adjacent crossing stations shall be divided into a series of Signalling sections and entry into each signalling section shall be controlled by a Manual Stop Signal or an Automatic Stop Signal or a Semi- Automatic Stop Signal which must assume 'ON' position on entry of a train into the section and be maintained in that position until the train has passed clear of the next Automatic Stop Signal in advance and also for an adequate distance beyond it. (d) No automatic signal shall assume 'OFF' position unless the Line is clear not only up to the next Stop Signal in advance but also for an adequate distance beyond it. Except under approved special instructions, this adequate distance shall not be less than; (i) 120 metres, if next Stop signal in advance is an automatic signal. (ii) 180 metres, if *next Stop signal in advance is a Manual stop signal or Semi-automatic signal. (*Note: if such signal is a Home signal or LC gate signal) (e) Signals shall be so spaced as to meet the operational requirements of the section. At the same time the distance between signals shall not be so high as to cause serious repercussions during failures or so small as to provide inadequate braking distance. If the distance between the Caution and Stop Aspects in the case of three aspect signalling or Attention and Stop Aspects in the case of four aspect signalling, is less than the Emergency braking distance of a train, the speed of that train shall be so regulated as to bring the Emergency braking distance within the above mentioned signal spacing. (f) The Signal that governs entry into the Block section shall be Manual or Semi-Automatic Stop Signal, which are explained below. 20.1.2 Manual Stop Signals and Semi-Automatic Stop Signals (a) Manual Stop Signals: Fixed Signals which require manual control each time they are taken 'OFF' are called Manual Stop Signals. Manual stop signals shall be manually operated multiple aspect colour light signals which shall assume ‘ON’ position automatically on the occupation of the section ahead but shall assume ‘OFF’ position only when on clearance of the relevant section and they are operated manually. Chapter 20: Automatic Block Signalling Page 420 of 530  (b) Semi-Automatic Stop Signals: A fixed signal having both manual and track circuit controls and which is capable of being operated either as an Automatic Stop Signal or a Manual Stop Signal, is called a Semi-Automatic Stop Signal i.e they are capable of being operated either as Automatic Stop Signals or as Manual Stop Signals as per need. (i) The Semi-Automatic Stop Signal when working as an Automatic Stop Signal shall conform to an Automatic Stop Signal in all matters relegating to its functioning including its normal aspect. (ii) Similarly, a Semi-Automatic Stop Signal when working as a Manual Stop Signal shall conform to Manual Stop Signals in all matters including its normal aspect. A control may be provided to make a Semi-Automatic Stop Signal to work either as an Automatic Stop Signal or as a Manual Stop Signal as required. 20.1.3 Special Requirements of Automatic Block System on Single Line: In case of single line , Line clear shall be obtained and Direction of Traffic shall be established as per GR 9.03 (Extract given below) GR 9.03. Essentials of the Automatic Block System on single line.–– (1) Where trains on a single line are worked on the Automatic Block System,--- (a) The line shall be provided with continuous track circuiting or axle counters, (b) The direction of traffic shall be established only after Line Clear has been obtained from the block station in advance, (c) A train shall be started from one block station to another only after the direction of traffic has been established, (d) It shall not be possible to obtain Line Clear unless the line is clear, at the block station from which Line Clear is obtained, not only up to the first Stop signal but also for an adequate distance beyond it, (e) The line between two adjacent block stations may, where required, be divided into two or more automatic block signaling sections by provision of Stop signals, (f) After the direction of traffic has been established, movement of trains into, through and out of each automatic block signaling section shall be controlled by the concerned Automatic Stop signal and the said Automatic Stop signal shall not assume ‘off’ position unless the line is clear up to the next Automatic Stop signal: Provided further that where the next Stop signal is a Manual Stop signal, the line is clear for an adequate distance beyond it, and (g) All Stop signals against the direction of traffic shall be at ‘on’. (2) Unless otherwise directed by approved special instructions, the adequate distance referred to in clauses (d) and (f) of sub-rule (1) shall not be less than 180 metres. Chapter 20: Automatic Block Signalling Page 421 of 530 20.1.4 Establishing Direction of Traffic for Automatic Stop Signals on Single Line (a) A Control shall be provided to establish direction of traffic and to ensure that conflicting signals cannot be taken off and a suitable indicator provided to indicate the direction established. It shall not be possible to change the direction unless the entire line between two crossing stations and the overlap in the direction to be established are Clear. The mechanism of the control shall, in addition, be suitably approach locked. (b) Automatic Stop Signals shall operate in the direction of traffic established. Those Automatic Stop Signals which are against the direction of traffic must exhibit 'ON' position. 20.1.5 Train Detection (Track Circuits/Axle Counter) for Automatic Signalling (a) The line shall be provided with track circuits or Axle Counters over its entire length and may be divided into a series of Automatic Signalling Track Sections. The Track Circuit for the overlap must be separated from the Track Circuits for the remaining portion of each signalling section. In case of Axle Counters, track section may be extended from foot of the next signal in advance up to an adequate distance beyond it. (b) DC Track circuits are not to be provided in block section, in future working due to maintenance issues. (c) Track circuits/Axle Counter shall also be provided on all passenger running lines as well as other reception lines between passenger lines including their connections to the main lines at all stations on the Automatic Section including stations at either end of the section. There shall be no dead section between the Track Circuits/Track sections of the station and the Track Circuits/Track sections of the Automatic Section. (d) The design of the Axle Counters between two adjacent stations, shall be such that, individual track sections in each direction shall have resetting facility from dispatching end station master in case of failure of equipment, with co- operation of receiving end station master for verification of last vehicle. (e) Redundancy may be provided in Track circuits/Axle Counters in the Automatic Section to improve availability. (f) Media diversity shall preferably be provided for Axle Counters. (g) Track indicator for Automatic Signalling on Single Line: An indicator shall be provided at each station to indicate whether the block section is occupied or clear. 20.1.6 Markers (a) Each Automatic Stop Signal shall be identified by its number and provided with a Marker consisting of a white disc with letter ‘A’ in black. (b) A Semi-Automatic Stop Signal shall be provided with a Marker which shall show a white illuminated letter ‘A’ against a black background when the signal works as an Automatic Stop Signal. Chapter 20: Automatic Block Signalling Page 422 of 530  (c) Such a Signal interlocked with a level-crossing shall be provided with a yellow disc with letters ‘G’ in black and an ‘A’ marker light. The ‘A’ marker shall be lit only when the gates are closed and locked against road traffic. (d) A Semi-Automatic Stop Signal shall be provided with a Marker which shall show a white illuminated letter 'A' against a black background when the signal works as an Automatic Stop Signal. (i) Such a Signal interlocked with a level-crossing shall be provided with an enamelled yellow disc with letters 'G' in black and an 'A' marker light. The 'A' marker shall be lit only when the gates are closed and locked against road traffic. (ii) When a Semi-Automatic Stop signal is required to protect a level crossing gate as also points, the signal may be provided with an illuminated 'AG' marker in addition to the illuminated 'A' marker. (e) The illuminated markers of a Semi-Automatic Stop Signal shall preferably be repeated at the place of operation of the Signal along with the aspects of the Signal. 20.1.7 Restrictions in Graded Sections (a) Automatic Signalling shall not be provided on sections with heavy and continuous falling gradients steeper than 1 in 80 unless the brake power of trains on the section is adequate to enable the trains being stopped at each of the Automatic Stop Signal. (b) The suitability of Automatic Signalling on heavy and continuous rising gradients shall be decided in consultation with the concerned Departments duly taking into account the ability of a train to start after it has been stopped at an Automatic Stop Signal. (c) Points and Crossings in Automatic Block Sections: Emergency Crossovers and Siding Points shall be secured and approach locked and detected by Signals reading over the Points. Section 2: Installation of Automatic Signalling 20.2.1 The installation and wiring shall be carried out as per approved plan and Circuit Diagrams. The circuits and equipment shall be so installed as to cause minimum failures while ensuring maximum safety. 20.2.2 Circuit Features for Auto Signals (a) The aspects of an automatic signal shall be controlled by the main signal in advance through lamp proving relays/object controller, in addition to the controlling relays. (b) All fail-safe circuits shall work on continuously energized principle such that any open circuit in wiring, relay contacts, etc. or loss of power supplies shall not cause an unsafe condition. Chapter 20: Automatic Block Signalling Page 423 of 530  (c) An automatic signal on a double line/single line shall require all tracks to be clear up to the next signal and an adequate distance beyond, before it can display 'OFF' position as per Para 20.1.1 (d). In case of Single Line, Direction of traffic, shall also be established. (d) LED signals of approved type by RDSO shall be used. (e) All external circuits shall be provided with double cutting arrangements. (f) The circuits shall be so designed that, if the lamp of the aspect displayed fails, the signal shall immediately assume the next restrictive aspect. Also if a signal which must display red aspect does not do so for any reason whatsoever, the signal in rear shall display a red aspect. (g) The circuit for illuminated 'A' marker of a Semi Automatic Signal shall be such that the 'A' marker lights up only when the signal is working as an automatic signal. (h) The circuit for illuminated 'AG' marker where provided shall be such that the 'AG' marker lights up only when the conditions for 'A' Marker to light up are satisfied except for the level crossing gate which may either be open to road traffic or may have failed. (i) The illumination of the 'A' marker shall prove the correct setting and locking of the points as required and ensures the back-locking of the route. Level crossing gates, if any, on the route shall be proved closed and locked to the road traffic. (j) The relevant information of Automatic Signalling gears in section should be available/visible at station like Signals Aspects, track status information, Axle Counter reset information and gate information. 20.2.3 Level Crossings in Auto Section: Please refer to Chapter 14, section 1 of SEM for working of LC gates, approach locking and audible warning to LC gate man. 20.2.4 Installations - Misc (a) Track circuits: Provisions contained in Chapter 17 of SEM shall be adhered to. (b) Power Supply: Provisions contained in Chapter 16 of SEM shall be adhered to. (c) Installation in 25 KV AC electrified areas: Provisions contained in Chapter 22 of SEM shall be adhered to. (d) Installation of Cables: Provisions contained in Chapter 15 of SEM shall be adhered to. (e) Extant guidelines on Installation, Testing & Commissioning shall be adhered to. Note: An example of Automatic signalling scheme using optical fibre cable(OFC), Multi Section Digital Axle Counter (MSDAC) and Object Controllers (of Electronic Interlocking) is given at Annexure: 20-A1 for information. Chapter 20: Automatic Block Signalling Page 424 of 530  Section 3: Maintenance of Automatic Signalling Section 20.3.1 LED signal lamps shall be replaced in case of failure/after completion of codal life. 20.3.2 Marker light shall be replaced on age cum condition basis. 20.3.3 The following shall be tested by the SSE/JE (Signal) at least once in a year: (a) Track Circuit control on signal and aspect control by signals in advance; (b) Automatic Cutting-in of the next restrictive aspect when the LED aspect of the main signal fails; (c) Interlocking equipments and circuits for level crossings and points; (d) The circuits that establish the direction of traffic in Single Line and prevent clearing of conflicting signals on sections provided with Automatic block Signalling on Single Line; (e) Axle Counter resetting circuits, if provided. 20.3.4 All failures reported by the Loco Pilots/Motor man shall be promptly attended. 20.3.5 Track Circuits/Axle Counter Maintenance (a) Adequate precautions should be taken after every track renewal work to ensure proper working of track circuits/Axle counters. (b) Provisions contained in Chapter 17 of SEM shall be adhered to. 20.3.6 Power Supply: Provisions contained in Chapter 16 of SEM shall be adhered to. 20.3.7 Cables: Provisions contained in Chapter 15 of SEM shall be adhered to. Section 4: Modified Semi-Automatic Signalling Working 20.4.1 (a) Under special instructions, one of the automatic stop signals between two stations in the automatic block signalling territory on Double Line may be made as modified semi-automatic stop signal in each direction. During abnormal conditions like fog, bad weather impairing visibility, Modified Semi- Automatic Signal may be worked by extinguishing ‘A’ marker in the manner prescribed under special instructions and this section shall also ensure that the ‘A’ Marker of the Advanced Starter Signal of the station in rear and Home signal of the station in advance shall also be extinguished. (Provisions as per para 9.01 of GR shall be ensured.) (b) Interlocking will be such that during mid-section Modified automatic signal working with ‘A’ marker extinguished, not more than two trains, one on either side of this modified stop signal, will be ensured by the signalling system between two stations in any given direction at any given point of time. The mid-section modified semi-automatic stop signal shall when ‘OFF’ depict the aspect (Green or Double Yellow etc.) based on the aspects and number of Automatic signals (including any other signal) between this signal and the Home signal of the receiving station. Chapter 20: Automatic Block Signalling Page 425 of 530  (c) Such Gate signal, which has been converted as mid-section modified Semi- Automatic Signal, is provided with ‘A’ & ‘AG’ markers. During modified Automatic Signalling working, these markers will be extinguished. (d) During normal conditions, mid-section modified semi-automatic stop signal shall work as normal automatic stop signal. (e) The mid-section Modified automatic signal shall be painted with alternate blue and white strips in between. (f) The relevant indications whether the signal is in normal automatic mode or modified semi-automatic mode shall be available to the station masters at both the ends. Note: This chapter has under mentioned Annexure S.No. Annexure No. Description 1 20-A1 Automatic Signalling Scheme with OFC, MSDAC & OC Note: This chapter has under mentioned Drawings in Appendix II S.No. Drawing No. Description 1 20-D1 Automatic Signalling Scheme with OFC, MSDAC & OC (Sheets-3) Chapter 20: Automatic Block Signalling Page 426 of 530 Para No. 17.6.2 (b), 20.2.4 Annexure: 20-A1 Automatic Signalling Scheme with OFC, MSDAC & OC Brief context The automatic signaling is implemented usually with DC track circuit, AFTC, Universal Axle Counter (UAC), Single Section Digital Axle Counter (SSDAC). Any Failure of auto signals will have cascading effect on Trains. In order to have much better availability, Optical Fibre Cables (OFC) along with Electronic Interlocking/Object Controllers and Multi Section Digital Axle Counters (MSDACs), with dual detection may also be used for Automatic Block Signalling (ABS) I. Introduction The scheme is explained for a typical block section consisting of three Automatic Block sections. The scheme consists of two components. One is controlling of aspects of Automatic signals based on the clearance of tracks ahead and other is Train/track detection for block section. (a) Signal aspects are controlled using Object Controllers, placed at controlling Auto section Goomties. (b) Continuous Train/track detection is achieved through MSDAC (Dual detection). For Installing the above two equipment along with necessary power supply, Auto section Goomties are provided in the block section, with each Goomty catering for one UP & one DOWN Automatic Signal. II. Description of the Scheme A. Auto Goomties UP and DOWN Auto signals are planned in such a manner that, they are near to a Auto goomty to drive them. An Auto Goomty (AG) (Relay hut) , works as RBG room for controlling these UP and DOWN Auto signals as shown below. Fig 1. Auto Goomties for controlling One Up & One Dn signal Chapter 20: Automatic Block Signalling Page 427 of 530 B. Electronic Interlocking (EI) and OCs Both stations ‘A’ and ‘B’ on either end of the block section are provided with Electronic Interlocking System. The Automatic Signals of either direction are controlled by the EI of Sending station, through the OCs provided in the AGs. Two OCs are provided in each AG, for controlling either direction Automatic Signals. This arrangement will ensure that if any OC has failed, only one direction traffic will get affected. OC for DOWN direction is connected to EI of station A, similarly OC for UP direction is connected to EI of station B. The communication media between AG and Station is through OFC and not through any copper cable. Two numbers of 24 fibre OFCs are provided on UP and DOWN directions for path diversity. Fig 2. Interconnection between OCs and EIs over OFC The communication arrangement between OCs and Central Interlocking Units (CIUs) in Station A – Station B Automatic section is given below. 1. The DOWN direction Automatic Signals from Station A – Station B are controlled by CIU of Station A with OC placed at Goomties at each location of signal. 2. Thus a, total 4 OCs are connected to Station A CIU corresponding to G-3, 4, 5 and one OC is placed at Station B to gather the information of Station B`s Down Home signal , in order to control the aspect of it`s rear automatic signal. (HYR, HHYR, DYR). 3. Channel A of OC No 24 at Station B is connected to Station A CIU over 4 fibers on UP direction 24 core fiber (Fiber 9, 10, 11 & 12). These fibers are patched in each and every location of goomties to have continuity of communication. 4. The architecture of EI provides for 8 number of ports and each port can be connected with 4 OCs except in case of VDUs where only one VDU can be connected to one port. The configuration of connection of these 4 OCs to CIU is given in Drawings. 5. The channel-A of 4 OCs is connected to M-0 port of CIU using 4 conductors of fiber, where primary of one OC is connected to secondary of another OC in cascading way. Similarly Channel-B of 4 OCs is connected to Channel B of M-0 Port using 4 fiber conductors. 6. Using this connection configuration, the Down direction OCs of 4 & 5 are cascaded and their Channel-A is connected to channel A of M-5 port on Up direction 24 fiber using its 5, 6, 7 & 8 conductors. Similarly Channel-B is connected to channel B of M- 5 port on DN direction 24 fiber using its 5, 6, 7 & 8 conductors. Hence the path redundancy is achieved by connecting channel-A on UP direction 24 fiber and Channel-B on DN direction 24 fiber. This arrangement is preferred keeping in view on the limitation of fibers. 7. In brief, the OC at G - 3 is connected to M-4 port, OCs at G – 4 & 5 are connected to M-5 port and OC at Station B is connected to M-6 ports of CIU at Station A. Chapter 20: Automatic Block Signalling Page 428 of 530  8. Bidirectional RS 485 to OFC converter is used as interface between dark fiber and CIU as shown below. Each OFC converter has one primary (Tx, Rx) and one secondary (Tx, Rx). Two converters are required to connect one OC (Ch-A and Ch-B) to one port at CIU end. Similarly two more converters are required at OC end. 9. Similarly, the allocation of fibers in Station B – Station A Up direction may be seen in drawings. C. MSDACs with Dual Detection The necessary requirement of Automatic block section is continuous track detection between adjacent block stations. MSDACs with dual detection (M&R), with one Detection Point (DP) on each rails of track are used for redundancy and auto resetting facility. However, both DPs will function simultaneously in Hot-standby mode, so that failure of any one of the DPs will not affect the track vacancy detection. In order to minimize the number of track sections, no separate track section has been made for overlap portion of auto-sections. A single track section includes route as well as overlap of a signal. Supervisory track sections have been formed using the DPs of track sections for automatically resetting the track sections. Each supervisory track section covers two (02) track sections. Supervisory track sections have overlapping boundaries. Fig 3. Track Sections and Supervisory track sections Chapter 20: Automatic Block Signalling Page 429 of 530 Two evaluators (EVs) (M&R) are provided in each AG as well as adjacent stations. The main DPS of UP and DOWN direction are connected to EV(M) and redundant(R) DPs of UP and DOWN direction are connected to EV(R). The MSDACs used in the present scheme have one dedicated COM-AdC board with ethernet port to communicate with adjacent EVs. The evaluated information from COM-AdC is transferred through it’s ethernet port to dedicated OFC, via an unmanaged ethernet switch as shown in Fig.4. The COM-AdCs of both M & R EVs are hot linked and any failure of one of the board does not hamper the track detection. Fig 4. Interconnection of EV with OFC via COM The ethernet switch used in Fig.4 is as shown below Chapter 20: Automatic Block Signalling Page 430 of 530  The MSDAC information through ethernet interface (Main & Redundant) is connected to the ethernet switch which transfers the same onto dark fiber. Two such switches are used at each location one each for UP and DOWN direction firbers. The Vital Relays (ACPRs) of each track section are picked up at the sending end of track section (either in AG or station). The status of vital relays is read by the OCs, and transmitted to Central Interlocking Unit for logic processing, and the status of aspects is again sent to corresponding OCs for driving the Automatic Signals. D. Reset features of MSDAC The reset arrangement is proposed at three levels using Track Sections and Supervisory Track Sections, two of which are automatic reset arrangements and one is manual reset. (i) L -I : Automatic reset with redundant track section: Once the train has cleared both the track sections, and any one of the track sections is in failure state, the track section, which is in clear condition will reset the one in fail condition. The track section, which is under reset is kept in preparatory mode and the clear track section information is used to clear the signal. (ii) L-II : Automatic reset with Supervisory track section: When a supervisory track section is clear, all the track sections falling completely within the jurisdiction of that supervisory track section can be assumed to be clear. If any track section fails and it’s corresponding supervisory track section is clear, it will automatically reset the failed track section. In case of automatic resetting with supervisory track section, the reset track sections will be kept under preparatory mode, and the corresponding signal will continue to be in ‘ON’ aspect, until a train with low speed enters and exits the track section with equal count at the boundaries of track section. (iii) L -III : Manual Reset with Line verification: In case of failure of Level -1 and Level -2 reset, manual resetting has to be carried out, which resets all the track sections in the section under consideration. One reset box at train sending station along with its corresponding Line verification (LV) box at other station is used to manually reset all the track sections between both the stations of a particular direction of movement. This reset can be done only when Station Masters of both the stations have ascertained that all the track sections between the stations are clear of trains in that particular direction.This will reset and set all the DPs in preparatory mode. The clearance of train in each section with balancing of count will make the track section clear and bring to its normal mode of working. E. Power Supply Arrangement Each AG is provided with a Mini IPS, for which the input supply of 230 V AC is from UP AT and DN AT at each location. The necessary power supplies for EI OCs and MSDAC are derived from the Mini IPS. MSDAC works on a voltage range of 19-72 V DC. Hence 24 V DC supply with suitable current capacity from Mini IPS serves the purpose. In stations, the necessary power supplies are derived from the Major IPS. Chapter 20: Automatic Block Signalling Page 431 of 530  F. Cable requirement Signaling Cable: In the stations, Home & Advance starter signals are directly fed from the EI/Relay room with standard signaling cable, with aspect repeating relays at signal locations. Automatic Signals at AG are directly fed using a 12 x 1.5 Sq.mm signaling cable from AG, without any repeater relay at site, as the distance is not more than 200 meter. Quad Cable: MSDAC evaluator to each DP requires 1 quad of 4 conductor. A separate 6 quad cable is used for each DP of dual detection (main + Stand-by) from the nearest Half location box provided for Signal cable termination at signal location. From AG to Half location box one 6 quad each is used for UP & DN directions. Disclaimer: (1) The scheme given above, was adopted in 2018 for Automatic Signalling work in Vijayawada – Gunadala – Mustabada section of Vijayawada division of SCRly, is only for Technical information of signal Engineers and does not indicate endorsement of any particular make of MSDAC or EI/OC. (2) Scheme will have to be suitably modified as per Technical requirements/Facilities in particular make of MSDAC & other equipments being used. Refer to Drawings 20-D1 in Appendix II Chapter 20: Automatic Block Signalling Page 432 of 530