Basics of Indian Railway Signalling PDF

S1 BASICS OF INDIAN RAILWAY SIGNALLING इ ररसेट IRISET S1 BASICS OF INDIAN RAILWAY SIGNALLING INDIAN RAILWAYS INSTITUTE OF SIGNAL ENGINEERING & TELECOMMUNICATIONS SECUNDERABAD - 500 017 Issued in July 2022 MISSION : To deliver knowledge to make the workforce competent and confident in their field of Working VISION : To make IRISET a technical institute of global repute VALUES : Discipline, Devotion to duty, Integrity, Competence, Team Working and Safe Working The Material Presented in this IRISET Notes is for guidance only. It does not over rule or alter any of the Provisions contained in Manuals or Railway Board’s directives Revision History Notes No. Version Revision details Issued on S1 A1 ----- ------- A2 November 2009 A3 July 2022 Drafted By G.V. Rao, ITD2 K. Uma Maheswara Rao, APS Checked By A. Kalyan Kumar, PS1 Approved By Y. Ramesh Babu, SPS DTP & Drawings by P.V. Surya Narayana, JE (D) No. of Pages 117 Date of Issue July 2022 Version No A3 In case of any suggestions please write to APS/PS1 or mail to APS/PS1 at email address [email protected]/ [email protected] © IRISET “This is the Intellectual property for exclusive use of Indian Railways. No part of this publication may be stored in a retrieval system, transmitted or reproduced in any way, including but not limited to photo copy, photograph, magnetic, optical or other record without the prior agreement and written permission of IRISET, Secunderabad, India” http://www.iriset.indianrailways.gov.in CONTENTS CHAPTER 1: INTRODUCTION TO RAILWAY SIGNALLING.................................................... 1 1.1 INTRODUCTION............................................................................................................ 1 1.1.1 Need for Signalling in Railways:...................................................................................... 1 1.1.2 Railway signaling versus Road signaling:........................................................................ 1 1.1.3 Railway Signalling conveys the following:....................................................................... 1 1.1.4 Evolution of Rail Transport.............................................................................................. 2 1.1.5 Evolution of Signalling..................................................................................................... 3 1.1.6 Signalling in Indian Railways........................................................................................... 4 1.1.7 CONTROL OVER MOVEMENT OF TRAINS.................................................................. 4 1.1.8 TIME INTERVAL METHOD............................................................................................. 5 1.1.9 SPACE INTERVAL METHOD......................................................................................... 5 1.2 SIGNALS........................................................................................................................ 6 1.2.1 BLOCK WORKING......................................................................................................... 6 CHAPTER 2: INTRODUCTION TO RULES, MANUALS AND SPECIFICATIONS.................... 7 2.0 INTRODUCTION:................................................................................................................. 7 2.1 General and Subsidiary Rules (G&SR)................................................................................. 7 2.1. 3 Signal Engineering Manual (IRSEM)............................................................................... 7 2.1.4 Telecom Manual:............................................................................................................ 7 2.1.5 A.C Traction Manual:...................................................................................................... 7 2.1.6 Permanent way Manual:................................................................................................. 8 2.1.7 Schedule of Dimensions (SOD):..................................................................................... 8 2.1.8 Block Manual.................................................................................................................. 8 2.1.9 Accident Manual:............................................................................................................ 8 2.2 Specifications:................................................................................................................. 8 2.2.1 Indian Railway Standard Specifications (IRSEM Ch 8.3.1).............................................. 8 2.2.2 Other Specifications (IRSEM Ch.8.3.1 (b))...................................................................... 8 CHAPTER 3: DEFINITIONS (GR 1.02)...................................................................................... 9 3.1 ACT................................................................................................................................ 9 3.2 ADEQUATE DISTANCE................................................................................................. 9 3.3 APPROACH LIGHTING.................................................................................................. 9 3.4 APPROVED SPECIAL INSTRUCTIONS......................................................................... 9 3.5 AUTHORISED OFFICER................................................................................................ 9 3.6 AUTHORITY TO PROCEED........................................................................................... 9 3.7 AXLE COUNTER............................................................................................................ 9 3.8 BLOCK BACK................................................................................................................. 9 3.9 BLOCK FORWARD........................................................................................................ 9 3.10 BLOCK SECTION........................................................................................................... 9 3.11 CENTRALISED TRAFFIC CONTROL............................................................................. 9 3.12 COMMISSIONER OF RAILWAY SAFETY...................................................................... 9 3.13 COMPETENT RAILWAY SERVANT............................................................................... 9 3.14 CONNECTIONS............................................................................................................. 9 3.15 CONTROLLER............................................................................................................. 10 3.16 DAY.............................................................................................................................. 10 3.17 DIRECTION OF TRAFFIC means................................................................................. 10 3.18 ELECTRICAL COMMUNICATION INSTRUMENT........................................................ 10 3.19 FACING AND TRAILING POINTS................................................................................ 10 3.20 FIXED SIGNAL............................................................................................................. 10 3.21 FOULING MARK........................................................................................................... 10 3.22 GANGMAN................................................................................................................... 10 3.23 GATEMAN.................................................................................................................... 10 3.24 GANGMATE................................................................................................................. 10 3.25 GOODS TRAIN............................................................................................................. 10 3.26 GUARD......................................................................................................................... 10 3.27 INSPECTOR OF WAY OR WORKS............................................................................. 10 3.28 INTERLOCKING........................................................................................................... 10 3.29 INTERMEDIATE BLOCK POST.................................................................................... 11 3.30 INTERMEDIATE BLOCK SIGNALLING........................................................................ 11 ( Ref : STS.E.IBS in Single Line dated 22/02/2018)................................................................. 11 3.31 ISOLATION................................................................................................................... 11 3.32 LAST STOP SIGNAL.................................................................................................... 11 3.33 LEVEL CROSSING....................................................................................................... 11 3.34. LEVEL CROSSING GATE............................................................................................ 11 3.35 LINE CLEAR................................................................................................................. 11 3.36 LOCO PILOT................................................................................................................ 11 3.37 MAIN LINE.................................................................................................................... 11 3.38 MATERIAL TRAIN........................................................................................................ 11 3.39 MIXED TRAIN............................................................................................................... 11 3.40 MULTIPLE ASPECT SIGNALLING............................................................................... 11 3.41 NIGHT.......................................................................................................................... 11 3.42 OBSTRUCTION............................................................................................................ 11 3.43 OVERHEAD EQUIPMENT............................................................................................ 11 3.44 PASSENGER TRAIN.................................................................................................... 11 3.45 POINT AND TRAP INDICATORS................................................................................. 12 3.46 RUNNING LINE............................................................................................................ 12 3.47 RUNNING TRAIN......................................................................................................... 12 3.48 SHUNTING................................................................................................................... 12 3.49 SPECIAL INSTRUCTIONS........................................................................................... 12 3.50 STATION...................................................................................................................... 12 3.51 STATION LIMITS.......................................................................................................... 12 3.52 STATION MASTER...................................................................................................... 12 3.53 STATION SECTION...................................................................................................... 12 3.54 SUBSIDIARY RULE...................................................................................................... 12 3.55 SYSTEM OF WORKING............................................................................................... 12 3.56 TRACK CIRCUIT.......................................................................................................... 12 3.57 TRAIN EXAMINER....................................................................................................... 12 3.58 CLASSIFICATION OF STATIONS................................................................................ 12 3.59 COLOUR LIGHT SIGNAL............................................................................................. 13 3.60 EMERGENCY BRAKING DISTANCE........................................................................... 13 3.61 IN REAR OF A SIGNAL................................................................................................ 13 3.62 IN ADVANCE OF A SIGNAL......................................................................................... 13 3.63 LINE CAPACITY........................................................................................................... 13 3.64 OVERLAP..................................................................................................................... 13 3.65 ‘ON' ASPECT................................................................................................................ 13 3.66 ‘OFF' ASPECT.............................................................................................................. 13 3.67 POSITION LIGHT SIGNAL........................................................................................... 13 3.68 SERVICE BRAKING DISTANCE.................................................................................. 13 CHAPTER 4: FIXED SIGNALS, ASPECTS & INDICATIONS.................................................. 14 4.3 MULTIPLE ASPECT COLOUR LIGHT SIGNALS......................................................... 14 4.4 Distant Signal Aspects (SEM 7.1.12 ( a ) ).................................................................... 16 CHAPTER 5: DESIGNATION OF SIGNALS............................................................................ 18 (IRSEM CHAPTER -7)............................................................................................................. 18 5.1 INTRODUCTION.......................................................................................................... 18 5.2 SIGNALS FOR RECEPTION........................................................................................ 18 5.3 SIGNALS FOR DEPARTURE OF TRAINS................................................................... 18 5.5 ASPECT SEQUENCE CHART OF STOP SIGNALS USED FOR DEPARTURE OF TRAINS......................................................................................................................... 19 CHAPTER 6: SUBSIDIARY SIGNALS, INDICATORS & MARKERS...................................... 21 6.1 INTRODUCTION.......................................................................................................... 21 6.2 SUBSIDIARY SIGNALS................................................................................................ 21 6.3 SHUNT SIGNALS (GR 3.14)......................................................................................... 21 6.4 POSITION LIGHT SHUNT SIGNAL (SEM 7.1.19)........................................................ 22 6.5 SHUNTING MOVEMENTS AND SHUNT SIGNALS IN GENERAL............................... 23 6.6 CALLING ON SIGNALS (GR 3.13, SEM 7.1.18)........................................................... 24 6.8 INDICATORS................................................................................................................ 27 6.9 TARGET TYPE POINT AND TRAP INDICATORS (SEM 7.4.5 ( a, b ))......................... 27 6.10 ROUTE INDICATORS AND JUNCTION TYPE INDICATORS...................................... 27 6.11 BOARDS....................................................................................................................... 28 CHAPTER 7: OVERLAPS (SEM 7.1.8 & 7.1.9)....................................................................... 33 CHAPTER 8: BRAKING DISTANCE....................................................................................... 36 8.1 INTRODUCTION.......................................................................................................... 36 8.2 SERVICE BRAKING DISTANCE.................................................................................. 36 8.3 EMERGENCY BRAKING DISTANCE........................................................................... 36 8.4 TRAIN BRAKING DISTANCE....................................................................................... 36 CHAPTER 9: SIGHTING DISTANCE & VISIBILITY OF SIGNALS.......................................... 38 9.1 INTRODUCTION.......................................................................................................... 38 9.2 MINIMUM SIGHTING DISTANCE (SEM 7.7)................................................................ 38 9.3 AUTOMATIC BLOCK SIGNALS................................................................................... 38 CHAPTER 10: ISOLATION (SEM 7.4.9).................................................................................. 40 10.1 INTRODUCTION:......................................................................................................... 40 10.2 THE PROVISION OF ISOLATION DOES NOT APPLY TO........................................... 40 10.3 MEANS OF ISOLATION (SEM 7.4.10)......................................................................... 41 CHAPTER 11: SIMULTANEOUS RECEPTION AND DESPATCH OF TRAINS...................... 45 11.1 INTRODUCTION.......................................................................................................... 45 11.3 Simultaneous Reception............................................................................................... 45 11.4 Simultaneous reception and dispatching....................................................................... 47 CHAPTER 12: SYSTEMS OF WORKING (GR 7.01)............................................................... 48 12.3 SYSTEMS OF TRAIN WORKING................................................................................. 48 12.4 ABSOLUTE BLOCK SYSTEM (GR 8.01)...................................................................... 48 12.5 AUTOMATIC BLOCK SYSTEM.................................................................................... 50 12.5.1 Automatic Block System on Double Line (GR 9.01)...................................................... 50 12.5.2 Procedure for passing an automatic stop signal displaying the red aspect (on Double line)............................................................................................................................... 53 12.5.3 Gate Signals................................................................................................................. 54 12.5.4 Automatic Block System on Single Line (GR 9.03)........................................................ 54 12.5.5 Essentials of Automatic Block System on Single Line (GR 9.03)................................... 54 12.5.6 Minimum equipment of fixed signals in Automatic Block Territory on single line............ 55 12.5.7 Additional fixed signals in Automatic Block territory on single line................................. 55 12.5.8 Illuminated AG marker with illuminated `A' marker........................................................ 55 12.5.9 Modified Semi-Automatic Signalling Working................................................................ 55 12.6 Restrictions in Graded Sections.................................................................................... 57 CHAPTER 13: CLASSIFICATION OF STATIONS - A, B & C................................................. 59 13.1 CLASSIFICATION OF STATIONS (GR 1.03)................... Error! Bookmark not defined. INTRODUCTION:..................................................................................................................... 59 13.4 COMPARISION OF CLASS A, B AND C STATIONS.................................................... 60 13.4.1 Class A & B Stations..................................................................................................... 60 13.5 COMPARISON OF CLASS `A' AND CLASS `B'............................................................ 61 13.6 CLASS `C’ STATIONS.................................................................................................. 61 13.7 MULTIPLE ASPECT SIGNALLING (M A S).................................................................. 61 CHAPTER 14: STANDARDS OF INTERLOCKING................................................................. 64 14.1 INTRODUCTION.......................................................................................................... 64 14.3 STANDARD OF INTERLOCKING AS PER IRSEM...................................................... 64 CHAPTER 15: OPERATION OF POINTS OVER INDIAN RAILWAYS.................................... 67 15.1 INTRODUCTION.......................................................................................................... 67 15.2 OPERATION OF POINTS............................................................................................. 67 15.3 LOCATION OF POINT AND RANGE OF OPERATION................................................ 67 15.4 PARAMETER FOR SETTING OF SWITCHES............................................................. 68 15.5 SPEED OF TRAIN OVER POINT STANDARD WISE................................................... 68 CHAPTER 16: INTER CABIN CONTROL................................................................................ 69 16.1 PRINCIPLES OF SLOTTING........................................................................................ 69 16.1.1 The purpose of slotting is two fold................................................................................. 69 CHAPTER 17: LOCATION OF SIGNALS................................................................................ 70 17.1 INTRODUCTION:......................................................................................................... 70 17.3 LOCATION OF SIGNALS IN MACL SIGNALLING........................................................ 70 17.4 LOCATION OF SIGNALS IN COLOUR LIGHT SIGNALLING....................................... 71 CHAPTER 18: LEVEL CROSSING GATES............................................................................ 77 18.1 INTRODUCTION (Chapter 7 and Chapter 20 of IRSEM).............................................. 77 18.2 CLASSIFICATION OF GATES...................................................................................... 77 18.3 LOCATION OF LC GATE............................................................................................. 82 18.5 WARNING ARRANGEMENTS...................................................................................... 82 18.6 PROTECTION OF L.C.GATE INSIDE THE STATION LIMITS...................................... 82 18.7 LEVEL CROSSING LOCATED WITHIN STATION LIMITS IN MAS SIGNALLING........ 83 CHAPTER 19: SECTION CAPACITY...................................................................................... 89 19.1 INTRODUCTION.............................................................................................................. 89 19.2 Scott’s FORMULA............................................................................................................ 89 CHAPTER 20: PRINCIPLES OF SIGNAL ENGINEERING...................................................... 91 20.1 INTRODUCTION.............................................................................................................. 91 20.2 PRINCIPLES OF SIGNAL ENGINEERING................................................................... 91 ANNEXURE 1: FIXED SIGNALS, ASPECTS & INDICATIONS............................................... 97 A1.6 Two aspect Lower Quadrant Signalling......................................................................... 98 A1.12 Multiple Aspect Upper Quadrant Signalling................................................................. 101 FIG. A1.4 (a) MAUQ - STOP SIGNAL.................................................................................... 102 A1.13 LOCATION OF SIGNALS............................................................................................ 103 A1.14 LOCATION OF SIGNALS IN 2-ASPECT L.Q.SIGNALLING........................................ 103 A1.15 LOCATION OF SIGNALS IN MAUQ SIGNALLING..................................................... 106 A1.16 LOCATION OF SIGNALS IN (MLQ) MODIFIED LOWER QUADRANT SIGNALLING. 108 A1.17 LOCATION OF SIGNALS IN COLOUR LIGHT SIGNALLING..................................... 108 ANNEXURE 2: SUBSIDIARY SIGNALS, REPEATERS, INDICATORS,............................... 110 MARKERS & BACK LIGHTS................................................................................................ 110 A2.2 SUBSIDIARY SIGNALS.............................................................................................. 110 A2.3 SHUNT SIGNALS (GR 3.14)....................................................................................... 110 A2.4 DISC TYPE SHUNT SIGNAL...................................................................................... 111 A2.5 POSITION LIGHT SHUNT SIGNAL............................................................................ 112 A2.6 MINIATURE SEMAPHORE ARM TYPE SHUNT SIGNAL........................................... 113 A2.7 SHUNTING MOVEMENTS AND SHUNT SIGNALS IN GENERAL............................. 113 A2.8 CALLING ON SIGNALS.............................................................................................. 114 A2.11 OTHER MISCELLANEOUS SIGNALS........................................................................ 115 CHAPTER 1: INTRODUCTION TO RAILWAY SIGNALLING 1.1 INTRODUCTION Railway signaling is a system used to direct railway traffic and keep trains clear of each other at all times. Trains move on fixed rails, making them uniquely susceptible to collision. This susceptibility is further increased by the enormous weight and inertia of a train, which makes it difficult to quickly stop when encountering an obstacle. 1.1.1 Need for Signalling in Railways: Signalling in railways has evolved for the following: (a) Running trains safely by securing it`s intended path. (b) Handle more trains effectively. (c) Unambiguous & Timely Communication to Loco Pilot for regulating speed of train The Train Loco Pilot is very much dependent on the aspect of the signal for controlling the speed of train. Various Equipments or Systems are used for achieving above objectives. These equipments are getting modernized over time with added benefits. We are aware that at Railway Stations, there are more lines (tracks) in the stations. These stations are designed to receive, stop &dispatch trains in accordance with a schedule / program by prioritizing movement of some trains over other trains. This is enabled by signalling system which ensures safety at stations as well as between stations. 1.1.2 Railway signaling versus Road signaling: (a) Movement on Fixed Track: Trains are confined to move on Railway Tracks only. (b) Diversion from one track to another: Since many trains have to be handled at station (Place where more than one train is dealt at any time), and to prioritize sending one train over another, Trains have to be admitted in different lines by suitably diverting them from one track to another. But Train has no steering for taking diversion from one track to another. Then how does a train take a turn? Wheel Flanges have a rim which is guided along the track by a Track mechanism called Point assembly, whose setting decides whether train goes straight or diverted to other line. Train needs to slow down while taking diversions. For safe running of a train, correct setting of Points and holding them in the same position till complete passage of train is very vital. Advance intimation to bring the train to a halt / reduce speed: Due to its massive momentum and less friction on rails, a train requires considerable distance (about 300 mts to 1400 mts) to stop or even to slow down the speed after application of brakes. So whenever a Train has to be stopped either in normal course or out of course, Train Driver (now known as Loco Pilot) needs advance information for gradual application of brakes (as sudden application of brakes may lead to passenger discomfort or may even cause a derailment). The above features are not available in road signalling. 1.1.3 Railway Signalling conveys the following: (a) Timely information to Loco Pilot for regulating speed of his train. (i) Information is conveyed by a signal showing various aspects. IRISET Page 1 (S1) BASICS OF INDIAN RAILWAY SIGNALLING (ii) Many signals are interlinked for giving advance information. (b) A signal ensures (i) Physical clearance of intended path. (ii) Securing various points in the path. (iii) Closure of Level crossing gates. (iv) No other train is moving in this path. (c) As the demand for Train Traffic (both for Passengers & Goods) continue to increase over a period of time, Signalling system has also been developed to handle increasing Train traffic. Thus Signals play a very vital role in safe Train Operations. 1.1.4 Evolution of Rail Transport With Industrial Revolution in Europe and development of Steam Engine, Transport of Carriages on Steel Rails came in to use. The Stockton & Darlington Railway in north-east England is credited as the first Steam hauled passenger train, which was opened on 27 September 1825, as Britain's first passenger train. Around the same period, the rail transport was developed all over the Europe with different gauges (gauge is the distance between the inner sides of the heads of the two rails of the track). Type of Gauge Sn. Country gauge in mm 1 Broad 1676 India , Pakistan, Srilanka, Brazil England, USA, Canada, & China, Delhi Metro 2 Standard 1435 Rail Corporation 3 Meter 1000 India, France, Switzerland & Argentina Table 1.1 Different Gauges Lord Dalhousie, the Governor General of India introduced railways in Undivided India. The first train was inaugurated in India on 16th April, 1853 at 15:35 hours from Bori Bunder (suburban of Mumbai) to Thane with the locomotives named Sindh, Sultan, and Sahib hauling 14 railway carriages and 400 guests with a 21-gun salute covering a distance of 21 miles (34 km) in one hour and fifteen minutes, formally heralding the Birth of railways in India. Since then Indian railways has undergone transformation and became one of the leading rail transport systems in the world. Majority of track over Indian railway is broad gauge, with few Meter & Narrow gauge lines in use at some places. IRISET Page 2 (S1) BASICS OF INDIAN RAILWAY SIGNALLING 1.1.5 Evolution of Signalling In the beginning of Railway, the trains were run on messages, candle light signals. The trains were being run on Train Order System i.e. fixed crossings as per predetermined schedule. There was hardly any connection between signal and points / switches. The correlation between correct setting of point / switches for a route, taking ‘OFF’ signal for that route and maintaining point in locked conditio condition n during passage of train was at the judgment of operator of signal, thus prone to human errors. Signalling evolved over a period of time i.e. beginning with a man on horseback for guiding a train, free disk and crossbar signals. Lower quadrant Semaphore signals, upper quadrant Semaphore signals, colour light signals and to present day Communication based cab signalling. EVOLUTION OF SIGNALLING Sn. Description On Aspect OFF Aspect 1 A man used to ride on horseback moving in front of a Locomotive 2 Red Boards or flags were used in 1829 to control train traffic 3 Red Boards with candle 4 Semaphore Signals without Spectacle IRISET Page 3 (S1) BASICS OF INDIAN RAILWAY SIGNALLING EVOLUTION OF SIGNALLING Sn. Description On Aspect OFF Aspect 5 Lower Quadrant Semaphore with Spectacle 6 Upper Quadr Quadrant Semaphore with Spectacle 7 Colour Light Signal Table 1.2 Evolution of Signalling ( Ref : Art & Science of Railway Signalling by R.C.Sharma) 1.1.6 Signalling in Indian Railways In 1889, East Indian n Railway appointed, the first Signal Engineer in India Mr. S T Dutton. The List system of interlocking (named after British engineer Mr. G H List) for signalling was introduced in 1892 at six single single-line line crossing stations between Lahore and Ghaziabad of the t then North Western Railway , using a detector and locking system for protecting facing points. The system was enhanced by A Morse and came to be known as List & Morse interlocking. The earliest full cabin interlocking arrangements were installed at Bombay-Delhi Delhi route in 1893 with equipment from Saxby and Farmer of the UK. The List & Morse system was employed at 29 single-line line crossing stations between Lahore and Ghaziabad in 1894. 1.1.7 CONTROL OVER MOVEMENT OF TRAINS Running of flanged wheels of vehicl vehicles es on the steel track has its own inherent problems unlike the road transport, where the movement is not confined to a particular path. Since the vehicles are constrained to move in a fixed Railway track, they cannot be steered away as in the case of other means of transport. They are required to follow one another in the same direction on the length of track, as otherwise for every vehicle separate paths are to be provided. This is not practicable. If vehicles are expected from the opposite direction ano another set of diversion track is required to be provided either for overtaking vehicles moving in the same direction or for crossing the vehicles coming from the opposite direction. Railway locomotion, therefore, though more efficient, brings in problems of "Control over movement of Trains". IRISET Page 4 (S1) BASICS OF INDIAN INDIA RAILWAY SIGNALLING Basically, two types of controls could be catered for. If two separate tracks are provided for trains running in opposite directions, then one set of control can be provided to space the movement of trains running in the same direction so that adequate "interval" is available between two consecutive trains. On the other hand, if a single track is used for movement of trains in both directions, then another set of control is required to prevent a train in the opposite directions coming from on the same track when a train is already occupying it. 1.1.8 TIME INTERVAL METHOD Let us take the first case of spacing of trains in the same direction. The spacing should be such that if a train stops, then, the following train Loco Pilot should be able to notice it and apply brakes to his train so that it stops short of the preceding train. The most important aspect is bringing to a stop from the speed at which the train is running. Where the speed and load are low, it is not difficult for a following train to stop short of the train ahead, which has stopped. This is how tramways operate even today, as the speed and load are low and a tram can be stopped from its running speed without colliding with a tram in front. With higher speed and heavier load, as in the case of Railway train, the distance required to stop a train is longer, and at this longer distance, the Loco Pilot cannot definitely decide whether a train in front has actually stopped or not. This is the case when trains follow one another in quick succession. In actual practice, where interval between trains is longer, a following train does not see the earlier train, and the Loco Pilot has to continuously guess as to where the earlier train will be. If all trains run at the same speed and are required to stop at the same place for the same duration, a certain amount of control can be exercised by having a definite time lag between the trains from one stopping place to another. This time lag should be such that the train, which has a stop, is able to reach the next stop within this time. Thus by having a time interval between trains, a certain amount of control can be achieved. But, in the case of Railway, this is not practicable, as (a) Different types of trains are operated like Rajadhani / Shatabdi, Superfast, Mail / Express, passenger and high/ low speed freight trains etc. (b) Speed of trains varies. (c) Terrain is not same throughout the country. (d) Hauling capacity, Load of train and Brake power is not same for all trains; and (e) Stopping places of all trains are not the same. Hence, it is not possible to control the movement of trains under the "Time interval method". A better method of control called the "Space Interval Method" is adopted. 1.1.9 SPACE INTERVAL METHOD In this method of "Control over movement", the length of track is divided into sections called "Blocks". The entry of a train into the ‘block’ is controlled in such a way that only when it is free, a train can be allowed to enter in it. This means that between two consecutive trains, there is a definite space interval. This space interval or block is controlled at the entry. This controlling point should know whether the train, which had entered in this space, vacated it so that another following train can be sent. Since the length of a block is beyond the normal visual range, another controlling point is set at the end of the block. This controlling point can know whether the train has arrived and advise the controlling point at the entry. So, with the two controlling points and intercommunication, it is possible to control the entry of a train into a block only when it is vacant. IRISET Page 5 (S1) BASICS OF INDIAN RAILWAY SIGNALLING The information about the condition of this block is given by the exit point to the entry point, and the entry point transmits this information to the Loco Pilot of a train. The Loco Pilot of the approaching train must be able to know whether the next block is clear or not. He should stop the train and wait if the block section ahead is not clear. Here the role of "Signal" comes in to picture. 1.2 SIGNALS A "Signal", therefore, is a means to convey a particular pre-determined meaning in non- verbal form. Various methods are used to convey the meaning by "Signals" in a non-verbal form as are used by Scouts, Policemen, road signs, Navy and Air Traffic Control, etc., which convey a definite information. The chart below gives the various forms that are being adopted. Fig 1.1 Types of Signals 1.2.1 BLOCK WORKING As explained earlier, the space interval system uses the block working wherein the entry of train into the “block section” is jointly controlled by the entry and exit points of the block section. The Loco Pilot is authorised to proceed into the block section by the signal controlling the entry to the block section. This working could be a manual block system or automatic block system. In both types, before the train could be allowed to enter a section "PERMISSION" is required to be obtained from the Exit end to the effect that the section is "CLEAR" of trains and the train could be permitted. Different systems of working for getting this “PERMISSION TO ENTER” into the block section have been evolved on Indian Railways and are classified as "Systems of Working". The details of systems of working are explained in Chapter 12. Thus it can be concluded from the above, that the main purpose of Railway Signalling System is to maintain a safe distance between trains on the same track. IRISET Page 6 (S1) BASICS OF INDIAN RAILWAY SIGNALLING CHAPTER 2: INTRODUCTION TO RULES, MANUALS AND SPECIFICATIONS 2.0 INTRODUCTION: This chapter gives brief idea about General Rules, Subsidary Rules, various manuals related to Signal and Telecommunications department and their purpose. A brief about schedule of dimensions and Specifications is also given. 2.1 General and Subsidiary Rules (G&SR) The General Rules for Open Lines of the Railways 1976 have been framed under Section 198 of the Railways Act 1989 by the Government of India. General Rules for Indian Railways (Open Lines) 1976 administered by the Government and for the time being used for the public carriage of passengers, animals or goods.GR deals with the Rules applicable to Railway servants in general. 2.1.1 The Subsidiary Rules and the Special Instructions of the Zonal Railways are issued by the Principle Chief Operations Manager, the Authorized Officer, on the authority of GR 1.02 (5). 2.1.2 Whenever necessary, the General Rules are amended by the Government of India, whereas, the Subsidiary Rules and Special Instructions are amended by the Authorized Officer. The General Rules are printed in bold letters, while the Subsidiary Rules are printed in smaller letters, below the General Rules, with the same numbers of the General Rules which they refer. Subsidiary Rules and special instructions shall be read in conjunction with the General Rules. Every Railway Servant is bound under Section 175 of the Railways Act 1989 by the General Rules, the Subsidiary Rules and special instructions. 2.1. 3 Signal Engineering Manual (IRSEM) Signal Engineering Manual deals with items of general nature, organization of Signal and Telecommunication department, duties and responsibilities of Officers and staff at various levels and general requirements for installation of signaling equipments etc. Annexure –A & B deals with specific instructions regarding installation and maintenance schedules of various signaling systems, sub-systems and equipments. This manual is issued by Railway Board, 2.1.4 Telecom Manual: This manual provides detailed guidelines for setting up and maintaining the telecommunication systems. This manual also gives an overview about Organization of t he Signal and Telecommunication Department both at Headquarters and at Division. This manual is issued by Railway Board, 2.1.5 A.C Traction Manual: The "A. C. Traction Manual" contains installation, maintenance and operation of 25 kV/AC 50 Hz single phase traction installations, electric locomotives and electrical multiple units and other connected matters including railway electrification. The manual includes essential technical data for the use of operating and maintenance personnel. This manual is issued by Railway Board. IRISET Page 7 (S1) BASICS OF INDIAN RAILWAY SIGNALLING 2.1.6 Permanent way Manual: The manual contains uniform procedures and practices to be followed on Indian Railways by Engineering department. This manual includes duties of permanent way officials/men, maintenance of permanent way, working of motor trollies, lorries, track machines and material trains. The manual includes essential technical data for the use of operating and maintenance personnel. This manual is issued by Railway Board. 2.1.7 Schedule of Dimensions (SOD): The Schedule of Dimensions is meant to safeguard the interests of both the rail users as well as the railways and must be rigidly followed by the railways. This specifies various parameters of railway gears to be maintained for existing works and various parameters to be followed for new works. (For more details refer IRISET notes S8) This manual is issued by Railway Board. 2.1.8 Block Manual This manual contains instructions in detail regarding block working pertaining to that railway. It contains description of various block instruments, methods of working block instruments, use of special signals, and procedures in emergencies, testing of various block instruments and methods of sending a train from one block station to another. This manual is issued by Principle Chief Operations Manager. 2.1.9 Accident Manual: This manual contains all the rules regarding the class and description of accidents, accident Enquiries and procedures for reporting accidents. (For more details refer IRISET notes S27) This manual is issued by Principle Chief Operations Manager 2.2 Specifications: 2.2.1 Indian Railway Standard Specifications (IRSEM Ch 8.3.1) Specifications for materials used for signalling purposes have been drawn out by the Director General, Research, Designs and Standards Organisation (DG/RDSO), Ministry of Railways, Lucknow and are titled as "Indian Railway Standard Specifications”. These specifications are issued under a fixed serial number e g. S-12-54, the letter " S " denoting " Signals " the number " 12 " representing the serial number of the specifications and the final number " 54 " indicating the year of original adoption as standard, or in the case of revision, the year of last revision. 2.2.2 Other Specifications (IRSEM Ch.8.3.1 (b)) Specifications issued by the British Standards Institution, the Indian Standards Institution and the British Railway have also been adopted for items of equipment used for signalling purposes for which no IRS specifications exist. IRISET Page 8 (S1) BASICS OF INDIAN RAILWAY SIGNALLING CHAPTER 3: DEFINITIONS (GR 1.02) In order that interpretation of various terms remain clear and unambiguous, it is necessary to indicate their meanings precisely. This has been done in respect of common terms used in Railway signalling in chapter 1 of “General Rule”. Some of the important definitions are mentioned below. 3.1 ACT means the Indian Railways Act, 1989. 3.2 ADEQUATE DISTANCE means the distance sufficient to ensure safety. 3.3 APPROACH LIGHTING means an arrangement in which the lighting of signals is controlled automatically by the approach of a train. 3.4 APPROVED SPECIAL INSTRUCTIONS means special instructions approved of or prescribed by the Commissioner of Railway Safety. 3.5 AUTHORISED OFFICER means the person who is duly empowered by general or special order of the Railway Administration, either by name or by virtue of his office, to issue instructions or to do any other thing. 3.6 AUTHORITY TO PROCEED means the authority given to the Loco Pilot of a train, under the system of working, to enter the block section with his train; 3.7 AXLE COUNTER means an electrical device which, when provided at two given points on the track, proves by counting axles in and counting axles out, whether the section of the track between the said two points is vacant or occupied; 3.8 BLOCK BACK means to dispatch a message from a Block station intimating to the Block station immediately in rear on a double line or to the next Block station on either side on a single line, that the block section is obstructed or is to be obstructed; 3.9 BLOCK FORWARD means to dispatch a message from a Block station on a double line intimating to the Block station immediately in advance the fact that the block section in advance is obstructed or is to be obstructed. 3.10 BLOCK SECTION means that portion of the running line between two Block stations on to which no running train may enter until Line Clear has been received from the Block station at the other end of the block section. 3.11 CENTRALISED TRAFFIC CONTROL means a system by which the working of trains over a route, to which the system applies, is governed by fixed signals remotely controlled from a designated place. 3.12 COMMISSIONER OF RAILWAY SAFETY means an official appointed to exercise any function under the Act, and includes Chief Commissioner of Railway Safety; 3.13 COMPETENT RAILWAY SERVANT means a railway servant duly qualified to undertake and perform the duties entrusted to him. 3.14 CONNECTIONS When used with reference to a running line, means the points and crossings, or other appliances used to connect such line with other lines or to cross it. IRISET Page 9 (S1) BASICS OF INDIAN RAILWAY SIGNALLING 3.15 CONTROLLER means a railway servant on duty who may for the time being be responsible for regulating the working of traffic on a section of a railway provided with the system of speech communication. 3.16 DAY means from sunrise to sunset. 3.17 DIRECTION OF TRAFFIC means (a) On a double line, the direction for which the line is signaled. (b) On a single line, the direction for the time being established, under the system of working, to allow trains to move in that direction. 3.18 ELECTRICAL COMMUNICATION INSTRUMENT means either a telephone or a Morse Telegraph instrument. 3.19 FACING AND TRAILING POINTS Points are facing or trailing in accordance with the direction of a train or vehicle moves over them. Points are said to be facing points when by their operation a train approaching them can be directly diverted from the line upon which it is running. 3.20 FIXED SIGNAL means a signal of fixed location indicating a condition affecting the movement of a train and includes a semaphore arm or disc or fixed light for use by day and fixed light for use by night. 3.21 FOULING MARK means the mark at which the infringement of fixed Standard Dimensions occurs, where two lines cross or join one another. 3.22 GANGMAN means a railway servant employed on permanent way or works connected therewith; 3.23 GATEMAN means a competent railway servant posted at a Level crossing for working the gates. 3.24 GANGMATE means the person in charge of a gang of workmen employed on permanent way or works connected therewith. 3.25 GOODS TRAIN means a train (other than material train) intended solely or mainly for the carriage of animals or goods. 3.26 GUARD means the railway servant in charge of a train and includes a brakes man or any other railway servant who may for the time being be performing the duties of a Guard. 3.27 INSPECTOR OF WAY OR WORKS means any Inspector or Assistant Inspector responsible for the construction or maintenance of permanent way, points and crossings, bridges or other works connected therewith. (now re-designated as Senior Section Engineer/Junior Engineer). 3.28 INTERLOCKING means an arrangement of signals, points and other appliances, operated from a panel or lever frame, so interconnected by mechanical locking or electrical locking or both that their operation must take place in proper sequence to ensure safety. IRISET Page 10 (S1) BASICS OF INDIAN RAILWAY SIGNALLING 3.29 INTERMEDIATE BLOCK POST means a class `C' station on a double line, remotely controlled from the Block station in rear. 3.30 INTERMEDIATE BLOCK SIGNALLING means an arrangement of Signalling on double line / Single line in which a long block section is split into two portions each constituting a separate block section by providing an Intermediate Block Post. ( Ref : STS.E.IBS in Single Line dated 22/02/2018) 3.31 ISOLATION means an arrangement, secured by the setting of points or other approved means, to protect the line so isolated from the danger of obstruction from other connected line or lines. 3.32 LAST STOP SIGNAL means the fixed Stop Signal of a station controlling the entry of trains into the next block section. 3.33 LEVEL CROSSING means the intersection of road with railway track at the same level 3.34. LEVEL CROSSING GATE means any form of movable barrier, including a chain, capable of being closed across the road at the Level crossing but does not include a wicket or a turnstile for the use of pedestrians. 3.35 LINE CLEAR means the permission given from a Block station to a Block station in rear for a train to leave the latter and approach the former; or the permission obtained by a Block station from a Block station in advance for a train to leave the former and proceed towards the latter. 3.36 LOCO PILOT means the Loco Pilot or any other competent railway servant for the time being in charge of driving a train. 3.37 MAIN LINE means the line ordinarily used for running trains through and between stations. 3.38 MATERIAL TRAIN means a departmental train intended solely or mainly for carriage of railway material when picked up or put down or for execution of works, either between stations or within station limits. 3.39 MIXED TRAIN means a train intended for the carriage of passengers and goods, or of passengers, animals and goods. 3.40 MULTIPLE ASPECT SIGNALLING means a Signalling arrangement in which signals display at any one time any one of the three or more aspects and in which the aspect of every signal is pre-warned by the aspect of the previous signal or signals. 3.41 NIGHT means from sunset to sunrise. 3.42 OBSTRUCTION and its cognate expressions include a train, vehicle or obstacle on or fouling a line, or any condition which is dangerous to trains. 3.43 OVERHEAD EQUIPMENT means the electrical conductors over the tracks together with their associated fittings, insulators and other attachments by means of which they are suspended and registered in position for the purpose of electric traction. 3.44 PASSENGER TRAIN means a train intended solely or mainly for the carriage of passengers and other coaching traffic, and includes a troop train. IRISET Page 11 (S1) BASICS OF INDIAN RAILWAY SIGNALLING 3.45 POINT AND TRAP INDICATORS are not signals, but are appliances fitted to and working with points to indicate by day or by night the position in which the points are set. 3.46 RUNNING LINE means the line governed by one or more signals and includes connections, if any, used by a train when entering or leaving a station or when passing through a station or between stations. 3.47 RUNNING TRAIN means a train, which has started under an authority to proceed and has not completed its journey. 3.48 SHUNTING means the movement of a vehicle or vehicles with or without an engine or of any engine or any other self-propelled vehicle for the purpose of attaching, detaching or transfer or for any other purpose. 3.49 SPECIAL INSTRUCTIONS means instructions issued from time to time by the authorized officer in respect to particular cases or special circumstances. 3.50 STATION means any place on a line of Railway at which traffic is dealt with, or at which an authority to proceed is given under the system of working. 3.51 STATION LIMITS means the portion of a railway, which is under the control of a Station Master and is situated between the outermost signals of the station or as may be specified by special instructions. 3.52 STATION MASTER means the person on duty who is for the time being responsible for the working of the traffic within station limits, and includes any person who is for the time being in independent charge of the working of any signals and responsible for the working of trains under the system of working in force. 3.53 STATION SECTION Please see Chapter No - 13. 3.54 SUBSIDIARY RULE means a special instruction, which is subservient to the General Rule to which it relates and shall not be at variance with any General Rule. 3.55 SYSTEM OF WORKING means the system adopted for the time being for the working of trains on any portion of a railway. 3.56 TRACK CIRCUIT means an electrical circuit provided to detect the presence of a vehicle on a portion of track, the rails of the track forming part of the circuit. 3.57 TRAIN EXAMINER means a railway servant duly qualified to examine trains and certify their fitness for safe running and includes and their railway servant who may for the time being be performing the duties of Train Examiner.. 3.58 CLASSIFICATION OF STATIONS (a) Stations, shall for the purpose of these rules, be divided into two categories - Block stations and non-Block stations. (b) Block stations are those at which the Loco Pilot must obtain an authority to proceed under the system of working to enter the block section with his train; and under the Absolute Block System consist of three classes viz. `A', `B', `C', etc (see Chapter 13). IRISET Page 12 (S1) BASICS OF INDIAN RAILWAY SIGNALLING 3.59 COLOUR LIGHT SIGNALA fixed signal in which the indications are given by the colour of a light only. 3.60 EMERGENCY BRAKING DISTANCE is the distance travelled by train before coming to a stop by sudden application of brake at one stretch. 3.61 IN REAR OF A SIGNAL means the territory over which an approaching train has to pass before reaching the signal location. 3.62 IN ADVANCE OF A SIGNAL means the territory beyond a signal as seen from the approaching train. 3.63 LINE CAPACITY means the maximum number of trains that can be run on any given section during a calendar day of 24 hours. 3.64 OVERLAP means the length of track in advance of a stop signal, which must be kept clear, either for clearing the stop signal next in rear or for the purpose of granting permission to approach. 3.65 ‘ON' ASPECT means the most restrictive aspect of the signal. 3.66 ‘OFF' ASPECT means any aspect other than the `ON' aspect of a signal. 3.67 POSITION LIGHT SIGNALA fixed signal in which the indications are given by the position of two or more lights. 3.68 SERVICE BRAKING DISTANCE is the distance required to stop the train running at the maximum permissible speed of the line, at such a rate of deceleration that the passengers do not suffer discomfort or alarm. IRISET Page 13 (S1) BASICS OF INDIAN RAILWAY SIGNALLING CHAPTER 4: FIXED SIGNALS, ASPECTS & INDICATIONS (GR 3.05 -3.08) 4.1 INTRODUCTION: In earlier chapters a mention was made about the use of different types of visual and audible signals, for controlling the movement of trains in all cases. Different types of signals used for train operation are as under: (a) Fixed Signals (b) Hand Signals (c) Detonating Signals (d) Flare Signals 4.2 The definition of "Fixed Signals" as given in the General Rules is "a signal of fixed location indicating a condition affecting the movement of a train and includes fixed light for use by day and a fixed light for use by night”. 4.3 MULTIPLE ASPECT COLOUR LIGHT SIGNALS Colour Light signals which indicate one of three colours irrespective of day / Night, such signals are called Colour Light Signals. These are earlier used in busy suburban sections and main trunk routes, as these require electric power to operate them. Use of colour light signals is essential in the Electrified sections. Now a day’s most of the Signals provided are Colour Light Signals. Some of the advantages of Colour Light Signals over the semaphore signals are: (a) The day and night aspects are the same, therefore no confusion to the Loco Pilot. (b) The visibility can be obtained for longer range and the natural background adds to improve the visibility, especially they are excellent in the night. (c) The signals are placed at Loco Pilot's eye level. (d) The drooping of signal arm due to snow or external force is completely eliminated. (e) A combination of 4 aspects can be obtained. (f) No mechanical transmission, no moving parts, so no wear and tear, and long range of operation is feasible. (g) No kerosene is required and no necessity to depend on Operating Staff for lighting lamps. Further details may be seen in S-10 of IRISET notes on Colour Light Signalling The details of the aspects and indications of a Multiple Aspect Colour Light Stop Signal are as shown in Fig 4.1 (a) & (b). IRISET Page 14 (S1) BASICS OF INDIAN RAILWAY SIGNALLING ASPECT AND INDICATION OF MACL STOP SIGNAL (3 ASPECT) ASPECT Stop Caution Proceed Proceed & be prepared to stop at the next INDICATION Stop dead Proceed Stop Signal Fig 4.1 (a) MACLS – 3 Aspect Stop Signal ASPECT AND INDICATION OF MACL STOP SIGNAL (4 ASPECT) ASPECT Stop Caution Attention Proceed Proceed & be Proceed & be Stop prepared to INDICATION prepared to stop at Proceed dead pass next Stop next Stop Signal Signal Fig 4.1 (b) MACLS – 4 Aspect Stop Signal IRISET Page 15 (S1) BASICS OF INDIAN RAILWAY SIGNALLING 4.4 Distant Signal Aspects (SEM 7.1.12 ( a ) ) ASPECT AND INDICATION OF MACL DISTANT SIGNAL ASPECT Caution Attention Proceed Proceed & Proceed & be prepared to pass be prepared next Stop Signal at such speed INDICATION to stop at Proceed as prescribed by special next Stop instruction Signal Fig 4.1 (c) MACLS – Distant Signal Note: Where "Distant" and "Inner Distant" signals are provided the Distant shall display only "attention" or "proceed" aspect. (Ref. 3.07.1 SR -SCR) (a) In case of multiple aspects signalling, the Loco Pilot is not given any precise information about run through at the approach of a station. The distant signal at Green (OFF) indicates that he can proceed and expect the next stop signal to be OFF and further Stop Signals ahead of this may or may not be ‘OFF’ (as per revised aspects by Railway Board, Distant signal GREEN aspect indicate run through on main line). (b) 4-Aspect Colour Light Stop Signal at `OFF' with green light, indicates the Loco Pilot to proceed, next stop signal is also `OFF. Yellow aspect indicates caution and tells the Loco Pilot to proceed with caution and be prepared to stop at the next stop signal. In addition to the above aspects, a 4-Aspect Stop Signal has an attention aspect by showing of two yellow lights one above the other informs Loco Pilot to proceed and be prepared to pass the next stop signal at restricted speed. This may be on account of either the train has to negotiate a turn-out ahead or next signal at caution and the signal in advance to it is at Red, so that he can control the speed of the train. IRISET Page 16 (S1) BASICS OF INDIAN RAILWAY SIGNALLING 4.5 So far we have seen that a minimum of one stop Signal and a Permissive Signal is necessary to provide the requisite space interval between the trains. Trains are normally dealt with at stations for different purposes such as stopping for passengers, for loading, for servicing etc., in which case the stop signals are required to be located at different locations to cater to the needs. Stop signals could be provided at the approach end of a station and/or at the departure end of the station and/or at converging or diverging junction points at a station. This involves the introduction of calling the stop signals by different names depending upon the location and hence we will be discussing the details of "DESIGNATION OF SIGNALS" in the next chapter. Summary - Different types of signals used for train operation are Fixed Signals, Hand Signals and Flare Signals. Now a day’s most of the Signals provided are Colour Light Signals. Some of the advantages of Colour Light Signals over the semaphore signals are: (a) The day and night aspects are the same, therefore no confusion to the Loco Pilot. (b) The visibility can be obtained for longer range and the natural background adds to improve the visibility, especially they are excellent in the night. (c) The signals are placed at Loco Pilot's eye level. Multi Aspect signalling indications and aspects explained above. In MACLS territory distant, home , starters and advance starter signals provided. Review Questions Subjective Questions 1. List out name of the aspects and their indications of MACL FSS signal. 2. Write short note on Stop signal in MACLS territory. 3. Write name of the aspects of Distant signal in MACLS territory 4. Write name of the aspects of inner distant signal in MACLS territory Objective Questions Multiple choices 1. If distant signal in single distant territory display proceed aspect then it indicates ( ) a) Run through on main line b) Run through on loop line c) Train is going to be received on Main line d) All a, b & c 2. Total aspects of distant signal in double Distant signal territory is/are ( ) a) Attention b) a & c c) Proceed d) Caution 3. Name of the ON aspect of Home signal is ____________ ( ) a) Green b) RED c) Yellow d) White 4. Name of the permissive signal in MACLS territory is _________ ( ) a) Home sig b) Distant sig c) Calling – ON d) shunt sig IRISET Page 17 (S1) BASICS OF INDIAN RAILWAY SIGNALLING CHAPTER 5: DESIGNATION OF SIGNALS (IRSEM CHAPTER -7) 5.1 INTRODUCTION At a station it is obligatory to provide certain number of signals for controlling the movement of trains. There we require some signals to deal with the trains approaching the station and some to deal with departure of trains from the station. When more than one stop signals are used, it is difficult to identify them from each other. Hence it is necessary to give some name to these signals. 5.2 SIGNALS FOR RECEPTION Signals, which are governing the approach and entry of trains into a station, are, In Multiple Aspect Signalling a "DISTANT" signal is provided to indicate the Loco Pilot about the condition of the stop signal ahead. If the sectional speed is 120 kmph or above, two "DISTANT" signals may be provided. In such cases, these signals are called ‘DISTANT’ and ‘INNER DISTANT SIGNALS’ respectively. (a) STOP SIGNALS: Minimum one permissive and one stop signal are sufficient for trains approaching a station. When stop signal is taken 'OFF' it permits the train to enter the station, this is called "HOME" signal of the station. In some cases where the distance between the Home signal and the Reception lines of the station is far away, one more stop signal may be provided, as One Home signal will not be sufficient to facilitate the reception. So a stop signal provided between Home and the Reception lines shall be called as "ROUTING HOME". 5.3 SIGNALS FOR DEPARTURE OF TRAINS At the departure end of the station, the stop signals controlling the movement of trains leaving the station are : (a) STARTER SIGNAL ( SEM 7.1.14 ( C ) :Where the departure of trains is controlled by only one stop signal, it is called Starter Signal and is the Last Stop Signal of the station. If two or more converging lines are there, the Starter shall be placed outside all connections on the line to which it refers. Where advanced starter is also provided, the starter referring to any line is placed so as to protect the facing point or fouling mark and shall not be less than 400 mts in advance of the Home signal. (b) ADVANCED STARTER ( SEM 7.1.14 ( E ) :Where departure of trains is controlled by more than one Stop Signal, the Outer most starter signal shall be the Last Stop Signal of the station and is called "Advanced Starter". Unless approved under special instructions an "Advanced Starter" shall be placed outside all connections on the line to which it applies. It shall be placed at not less than 120 mts in multiple aspect signalling from the outermost point on single line and outside all point connections. This distance shall be reckoned from the starter on double line. On special nominated sections where frequent shunting involving main line takes place the "Advanced Starter" signal may be placed at a distance of full train length beyond the trailing point and the track between trailing point and the Advanced starter shall be track circuited. Where an advanced starter is provided, the starter referring to any line shall be placed so as to protect the first facing point or fouling mark; and shall not be less than 400 mts in advance of Home Signal. IRISET Page 18 (S1) BASICS OF INDIAN RAILWAY SIGNALLING (c) INTERMEDIATE / ROUTING STARTER: Intermediate Starter is provided between starter & advanced starter where necessary, and is placed in rear of the point, which it protects. 5.4 We have seen the aspects and indications of an individual signal. The following aspect sequence charts give us the various combinations of signals, their aspect and indications conveyed to the Loco Pilot of an approaching train. Approaching signals used in MACLS Distant HOME Indication Y R Train is required to stop at Home signal Y with YY Reception on Loop Line. Stop at Starter Route YY Y Reception on main line Stop at starters G G Run through on main line Table 5.1 Aspects Sequence Chart of Approaching Signals used in MACL Using two Distant Signals in approach (MACLS). ( SEM 7.1.12 ( b ) Distant Inner Distant Home Indication YY Y R Stop at Home Signal Enter on Loop Line. Stop at Starter if at YY YY Y with Route 'ON’ G YY Y Enter on Main Line. Stop at Starter G G G Run through via main line Table 5.2 Aspects Sequence Chart of Using two Distant Signals in approach (MACLS) 5.5 ASPECT SEQUENCE CHART OF STOP SIGNALS USED FOR DEPARTURE OF TRAINS Departure signals in MACLS Starter Advanced Starter Indication R R Stand in rear of starter signal Y R Shunt up to adv. Starter signal G G Proceed into Block section, line is clear Table 5.3 Aspects Sequence Chart of Departure signals in MACLS 5.6 To control the through movement of trains to and from a station, it is sufficient to have reception and despatch signals as explained above. But in some major yards, other special type of signals and indicators are provided, (a) to control shunt movements within the yard; and (b) to convey certain information to the Loco Pilot IRISET Page 19 (S1) BASICS OF INDIAN RAILWAY SIGNALLING Summary:- To control the movement of trains to and from a station, it is sufficient to have reception and despatch signals. Signals for reception of train are Distant, Inner Distant and Home signal and Signals for Dispatching of trains are Starter, Intermediate starter and Advance starter signals provided in each station.Aspect sequence chart also discussed for various combinations of signals Review Questions Subjective questions: 1. List out name of the reception signals used in MACL signalling 2. Describe distant signal aspects and indications 3. Write short note on starter signal in MACLS 4 Write down aspect control chart of distant signal in Double Distant territory. 5. Explain advantages of Double Distant signalling Objective Questions: 1. The Signals, which are governing the approach and entry of trains into a station section are __________ ( ) a) Signals for Reception b) Signals for Dispatching b) c)Detonating signal d) Miscellaneous signals 2. In Multiple Aspect Signalling a __________ signal is provided to indicate the Loco Pilot about the condition of the stop signal ahead ( ) a) Warner b) Distant c) Shunt d) Flare signal 3. If the sectional speed is 120 kmph or above, two "DISTANT" signals shall be provided, these signals are called __________ and __________ respectively ( ) a) Home & Calling On b) Distant & inner Distant c) Starter & shunt d) Calling ON & Shunt 4. Where the distance between the Home signal and the Reception lines of the station is far away, one more stop signal may be provided, as One Home signal will not be sufficient to facilitate the reception. So a stop signal provided between Home and the Reception lines shall be called a __________ ( ) a) Starter signal b) Routing Home signal c) Flare signal d)Distant signal 5. Where the departure of trains is controlled by only one stop signal, it is called __________ and is the Last Stop Signal of the station. ( ) a) Starter signal b) Shunt signal c) Intermediate starter sig d) Flare signal 6. The starter signal referring to any line is placed so as to protect the facing point or fouling mark and shall not be less than __________ meters in advance of the Home signal. ( ) a) 200 b) 600 c) 400 d) 1000 IRISET Page 20 (S1) BASICS OF INDIAN RAILWAY SIGNALLING CHAPTER 6: SUBSIDIARY SIGNALS, INDICATORS & MARKERS 6.1 INTRODUCTION In the previous chapters we have seen the signals authorising the Loco Pilots to enter the station from a block section by the use of Reception Signals; and enter into the block section from the station by the use of Departure Signals. These signals are used for “reception” and “despatch” of running trains. As per the definition a "Running train" is a train which has started under an authority to proceed and has not completed its journey whereas "a train" is an engine with or without vehicles attached or self propelled vehicle with or without a trailer which cannot be readily lifted off the track. The signals, which control the movement of trains within the station section, are to be differentiated and should convey different indication to the Loco Pilot. These signals are (a) Shunt signals and (b) Calling on Signals and are called as "SUBSIDIARY SIGNALS". 6.2 SUBSIDIARY SIGNALS In addition to the reception and despatch of train to and from a station some other movements of trains are also required such as transfer of vehicles from one line to another, attaching and detaching of vehicles to and from a train, so that vehicles meant for the same destination are always in one line etc. Such movements differ from regular train moves with the low speeds and these movements are confined to a small area and the line on which the movement is to be done may invariably be occupied by vehicles and as such the Loco Pilot has to exercise more caution called shunting movement of train. A running signal taken 'OFF' signifies that the line on which the movement is to takes place is clear of obstruction, where as a shunt signal taken 'OFF' authorise the Loco Pilot to pass the signal at slow speed irrespective of whether the line is vacant or not. These movements can be carried out by the use of "Hand Signals" exhibited by authorised persons to carry out the shunting. Where these movements are frequent and regular then the use of separate signals called "Shunt Signals" are to be fixed. Naturally the shunt signals are to be different from running signals as the information conveyed by them when 'OFF' is different. Moreover, as the movement is done in a smaller area, the visibility of the signal is not a criteria and low visibility is adequate. Also no pre-warning is necessary. Since visibility required is less, smaller types of signals can be used compared to running signals. 6.3 SHUNT SIGNALS (GR 3.14) (a) Shunt signals authorise movement only at such slow speeds as to be able to stop short of any obstruction and control shunting movements. (b) Shunt signals can be placed on a separate post by itself close to the ground or can be placed below a stop signal other than the first signal of a station. (c) More than one shunt signal may be placed on the same post in which case the top-most signal shall apply to the extreme left hand line and the second shunt signal from the top shall apply to the next line from the extreme left and so on. (d) Shunt signal when taken 'OFF' authorises the Loco Pilot to draw ahead with caution even though the stop signal, if any, above it is at 'ON' position (e) Shunt signal shall be either (i) Position Light Shunt Signal (f) When a Shunt Signal is placed below a Stop Signal, it shall show no light in the "ON" position. IRISET Page 21 (S1) BASICS OF INDIAN RAILWAY SIGNALLING 6.4 POSITION LIGHT SHUNT SIGNAL (SEM 7.1.19) A position light shunt signal provided generally in the Colour Light Signalling territory consists of a row of two white lights; one row for the 'ON' aspect and another row for the 'OFF' aspect. The position light shunt signal used in the multiple aspects Upper Quadrant is the same. Since this is also considered as a Colour Light Signal the day and night aspects are the same. The two lights of the position light shunt signals will be white. By day and by night, the lights of the position light shunt signal will be horizontal in the ‘ON’ position and 45º above horizontal in the 'OFF' Position. The aspects are shown in Fig 6.1 & 6.2. ‘ON’ POSITION ‘OFF’ POSITION ASPECT Stop Proceed Slow INDICATION Stop dead Proceed with Caution for Shunting Fig 6.1 Shunt signal below stop signal (Dependant Shunt Signal) Shunt signal on independent post Fig 6.2 Shunt Signals IRISET Page 22 (S1) BASICS OF INDIAN RAILWAY SIGNALLING 6.5 SHUNTING MOVEMENTS AND SHUNT SIGNALS IN GENERAL Shunt signals are additional signalling equipment provided at stations where shunting movements are very frequent and manual shunting is difficult to perform. Loco Pilot while busy in shunting movements should not refer to running signals. The conditions for taking 'OFF' a shunt signal in an interlocked station are the same as required for taking 'OFF' a running signal except, that it does not require signal overlap and isolation, berthing track clearance, released by another shunt signal, due to slow speeds. A shunt signal is generally not confined to one route/siding; it may read to any number of diverging lines ahead to which it is accessible. It conflicts with all running signals of the line to which the route of the shunt signal is set. Shunt signal is fixed on a post closer to ground, as it does not require long range visibility. On running lines where starters and advanced starter are provided, the starters of the station can be used for shunting. Where shunt signals are not provided, hand signals are used for shunting movements in such stations. ( A ) Shunting Permitted Indicator (SPI) – IRSEM 7.4.7 (a) Shunting Permitted indicator may be provided to permit uninterrupted to and fro movements towards shunting neck or other connected lines. Shunting Permitted Indicator may be of the Disc or Light type. (a) Indications of SPI: Day and night indications of the Shunting Permitted Indicator shall be as follows Shunting Permitted Indicator (SPI) Indication when shunting is Indication when shunting is not permitted in the direction to permitted in the direction to which which it refers it refers Type Night Day Indication Day Indication Night Indication Indication Disc Type Black disc with a Yellow cross Edge of disc No light yellow cross light painted on it Light Type Yellow cross Yellow cross No light No light light light (b) Operation of SPI: Shunting permitted Indicator may be operated by a ground lever/EKT which works in conjunction with a Stop Signal, so that either the shunting permitted indicator or the associated stop signal can be taken off at a time. IRISET Page 23 (S1) BASICS OF INDIAN RAILWAY SIGNALLING Fig 6.3 Shunting permitted indicator 6.6 CALLING ON SIGNALS (GR 3.13, SEM 7.1.18) A calling on signal is a subsidiary signal and has no independent existence. It is provided below a stop signal governing the approach of a train. "CALLING ‘ON' signal can be a colour light type in Multiple aspect territory. Typically these are located on Home & Starters signals (Not on LSS) and taken off after a time delay on occupation of its approach track. 6.7 Calling on signals are used only for the specific purpose of indicating to the Loco Pilot that he is required to draw ahead when Calling on signal is OFF and be prepared to stop short of any obstruction even though the stop signal above it, is at ON. Calling on signals are taken OFF only after the train has come to a stop. Calling on signals of the colour light type are provided with a ’C’ marker board. Under approved special instructions, a "calling on" signal may be provided below any stop signal except the Last Stop Signal (LSS). IRISET Page 24 (S1) BASICS OF INDIAN RAILWAY SIGNALLING Fig 6.4 4 (a) Distinguish Signs Provided on MACLS (b) MARKERS PROVIDED ON THE SIGNAL POST POST( GR 3.17 ) (i) Automatic stop signals are provided with ‘A’ Marker (letter ‘A’ in black on white circular disc) to distinguish the signal as a full automatic signal. (ii) Semi-automatic automatic stop signals are provided with ‘A’ lit marker (white illuminated letterr ‘A’ against black background) to distinguish the signal, when working as an automatic signal. Letter 'A' extinguishes when the signal is working as a manual signal. (iii) Colour light permissive signals on a post by itself are provided with ‘P’ Marker (letter 'P' in black on white circular disc) (iv) Gate stop signals are provided with ‘G’ Marker (letter 'G' in black on yellow circular disc.) (v) Intermediate block stop signals are provided with ‘IB’ Marker (letter 'IB' in black on white circular disc.) (vi) Colour light calling on signals are provided with ‘C’ Marker (letter 'C' in black on white circular disc.) (vii) Gate signals in Automatic Block territory are provided with a 'G' marker and a white illuminated minated letter 'A' against black background. Letter 'A' shall be lit when the gate is closed and locked against the road traffic. (viii) When a semisemi-automatic automatic signal is to protect a Level crossing gate and also points, the signal may be provided with illuminated 'AG' marker in addition to the illuminated 'A' marker, only one marker (either ‘A’ marker or ‘AG’ marker) marker can be lit at a time. When the points protected by the signal are correctly set and the gate is also closed, ‘‘A’A’ marker shall be lit. If the points are correctly set but the gate is defective, then ‘AG’ marker shall be lit. When both the markers are not lit, the signal shall be treated as manual stop signal. IRISET Page 25 (S1) BASICS OF INDIAN RAILWAY SIGNALLING APPEARANCE PROVIDED ON DISCRIPTION Letter ‘A’ in black on White Automatic Stop Signal. circular Disc. White illuminated letter ‘A’ against black background when Semi - Automatic Stop working as an automatic stop Signal. signal and letter ‘A’ extinguished when working as a manual stop signal. Colour light Distant or Warner Signal on a post Letter ‘P’ in black on White by itself in Two aspect circular Disc. CLS. APPEARANCE PROVIDED ON DISCRIPTION Intermediate Block stop Letter ‘IB’ in black on White signal circular Disc. Letter ‘C’ in black on White Calling ON Signal circular Disc. G Gate Stop Signal Letter ‘G’ in black on Yellow circular Disc. Letter ‘G’ in black on Yellow Gate stop signal in circular Disc and White automatic block territory. illuminated letter ‘A’ against black back ground. Gate stop signal in semi - automatic block White illuminated letters ‘A’ and territory, when ‘AG’ against black back ground. interlocked with points also. Fig 6.4 (b) Markers provided on Signal posts IRISET Page 26 (S1) BASICS OF INDIAN RAILWAY SIGNALLING 6.8 INDICATORS Certain appliances are provided on the un-interlocked points to indicate to the Loco Pilot and Points man, whether the points are set for the straight line or for the diverging line. These are called Point Indicators. Similarly, indicators are provided on the trap points to indicate whether they are open or closed. These are called trap indicators. Point indicators/trap indicators shall be provided at all points/traps on running lines, which are not interlocked with signals unless the position of points/trap points is otherwise provided. The indicators must display the same indication in both directions, whether the movement is in facing direction or in trailing direction over the points. Point indicators and trap indicators shall be of the target type. They are provided with Day and Night indications are shown below 6.9 TARGET TYPE POINT AND TRAP INDICATORS (SEM 7.4.5 (a, b )) All the Point indicators shall show a white target by day or a white light by night in both directions when the points are set for the straight and no target by day and a green light by night in both directions when the points are set for the turnout. SET FOR TURNOUT SET FOR STRAIGHT Fig 6.5 (a) Target type Point Indicators TRAP OPEN OR DERAIL ON TRAP CLOSED OR DERAIL OFF Fig 6.5 (b) Target type Trap Indicators 6.10 ROUTE INDICATORS AND JUNCTION TYPE INDICATORS We have already seen in the previous chapter that home signal of semaphore type can be provided one for each line either on a bracketed post or on a gantry. Similarly, for colour light signals, one signal can be provided for each line on a bracketed post or on a gantry. The number of colour light signals, one for each line can be replaced by one common signal with Route Indicators or Junction Indicator. Junction Indicator will be lit only for any diverted route along with common Main Signal, for straight line only the main signal will be lit in “OFF” position. IRISET Page 27 (S1) BASICS OF INDIAN RAILWAY SIGNALLING The Route Indicator can be a Stencil type or Multi-lamp type wherein the number of the line is made out for the Loco Pilot is exhibited either as a letter ‘M’ for Main Line, ‘B’ for Branch, etc. or as a numerical figure as Junction type Indicators are also provided which shows a row of lights one for each line or route as shown in Fig 6.6 Types of Route Indicators to be provided shall be as under: (a) Multiple aspect colour light signalling section :  For speed in excess of 15 kmph - Direction (Junction) type route Indicator - for three diversions on either side of main line  For speeds not exceeding 15 kmph - Any route Indicator of approved design. JUNCTION MULTI-LAMP TYPE STENCIL TYPE (DIRECTIONAL TYPE) Fig 6.6 Route Indicators (c) STARTER INDICATOR: At certain stations where colour light signalling is provided a Starter Indicator may be provided to repeat the aspect of the starter signal as an aid to the Guard to enable him to know the aspect of the starter signal. This indicator is fixed at a convenient place. It should show no light when starter signal is at 'ON' and show a yellow light when it is at 'OFF' 6.11 BOARDS (a) SHUNTING LIMIT BOARD (SEM 7.3.5): It is a board rectangular in shape with "Shunting Limit” painted in black at the bottom with a cross in black on a yellow background on the side facing the station. The board is fixed on a post, which is painted with black and white bands alternately as shown in Fig 6.11 (a). The shunting limit board is fitted with a lamp showing a white light on both directions to mark its position by night. This is provided on a single line class ‘B’ station where shunting in the face of an approaching train is permitted. The shunting limit board shall be placed at such a shunting distance from the outer most facing point as the local conditions may require, and shall not be less than 180 mts in Multiple Aspect Signalling. Shunting Limit Board demarcates the Station section and Block section. (b) BLOCK SECTION LIMIT BOARD (SEM 7.3.6): These boards are provided on Double line in multiple aspect signalling territory to distinguish the limit of the Block section. It shall be provided at a station where there are no facing points or the outer most point at the approaching end is trailing. It shall be placed at distance not less than 180 mts from the Home Signal and protects the fouling mark of the trailing point, if any. It is a board rectangular in shape with the words 'Block Section Limit Board' painted in a black at the bottom of the Board with a cross painted in black on yellow background on the side which faces the station. The board is fixed on a post, which is painted with black and White bands alternately. The block section limit board is fitted with a lamp showing a white light in both directions to mark its position by night. This is as shown in Fig 6.7 (a). IRISET Page 28 (S1) BASICS OF INDIAN RAILWAY SIGNALLING Fig 6.7 (a) Limiting boards (c) 'S' MARKER ( GR 3.35 ) : An intermediate siding taking off in the facing direction of running line outside station limits is provided with a 'S' marker to indicate to the Loco Pilot that a siding is being taken off from the main line. It is a circular board with letter 'S' painted in black on yellow background. The board is fixed on a post, which is painted with blac

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