Signalling Systems in Railways

ETCS Level 1

• Level 1 is a spot transmission system used as an overlay on an underlying signalling system.
• Trackside signals are required in Level 1 application.
• Track side equipment of Level 1 comprises of:
  • Balises
  • Line side electronic unit (LEU)
  • Communication link (data cable) between the LEU & the balise
• On-board equipment of Level 1 comprises of:
  • On-board Vital Computer (OBC)
  • Data logger for diagnostics
  • Driver Machine Interface (DMI)
  • Balise Transmission Module (BTM)
  • Balise antenna fixed to the under frame
  • Speed Sensors (e.g. Pulse Generators, Accelerometers, Radar)
  • Train Interface Unit (TIU)
  • Interface to existing brake control system
  • Power supply arrangement
  • Isolation arrangement for isolating the system
• The Trackside equipment does not know the train to which it is sending information.
• Movement authorities are generated by Trackside equipment and are transmitted to the train via balises.

Balises

• Balises pick up signal aspects from the trackside signals via Line side Electronics Unit (LEU) and transmit them to the vehicle as a movement authority along with track description data.
• The fixing arrangement of the balise on the sleeper shall be such that it does not require any drilling to the sleeper.
• Additional balises ("infill balises") can be placed in rear of signal to transmit infill information, so that the train will receive new information before reaching the signal.

Brake Commands

• Level 1 shall have two levels of brake commands:
  • Service brake command
  • Emergency brake command

Release Speed

• A release speed shall be calculated onboard to allow the train to approach the target (i.e. stop signal at ON) with such speed so as to ensure that the train stops before reaching the danger point up-to which train movement is considered safe (i.e., overlap distance beyond the stop signal at ON), based on data received.

TMS Functionalities

• Live Indications: Visual display wall, displaying track layouts of stations, auto sections, IBS and interlocked LC Gates of section monitored by TMS, indicating real-time status of track circuited lines, signal aspects, points, LC Gate etc.
• Live Indication to Train controller terminals: displaying complete information of yards covered by TMS with details of track circuits, signals, Points, LC gates etc.
• Train Describer System (TDS): associates a train with an alpha-numeric mark called a train describer tag, tracking the train in sections controlled by TDS.
• Decision Support System (DSS): identifies operational conflicts (like precedence, crossing etc.) in advance and suggests optimized control options to the controller.

ETCS Levels

• ETCS has Four Levels:
  • Level 0: A level of ATP defined to cover instances when the ATP on-board equipment is operating in an area where the trackside is not fitted with operational ATP equipment.
  • Level 1: A level of ATP overlaid onto conventional track side signalling that uses balises/loop/Radio Infill to pass movement authorities to the train whilst relying on conventional means to determine train position and integrity.
  • Level 2: A level of ATP that uses radio to pass movement authorities to the train whilst relying on trackside conventional means to determine train position and integrity.
  • Level 3: A level of ATP that uses radio to pass movement authorities to the train.Level 3 uses train reported position and integrity to determine if it is safe to issue the movement authority.

Event Log and Alarm Management System

• All important events (commands, indications, errors, system information) are logged in a database for later printing and analysis
• The replay function shows an history of events, displaying dynamic status for infrastructure, train number, and alarm list
• Traffic-related alarms include:
  • Train not described
  • Unscheduled train stoppage
  • Routes not released after passage of train
  • Failure of signalling gear
• Network-related alarms include:
  • Failure of network communication
  • Inability to access nodes
  • Defective terminals
  • Hardware and software failures

Decision Support System (DSS)

• Based on constraints and logic provided by railways, the system gives optimized decisions to admit or dispatch trains at entry/exit points
• In case of disruption, the system suggests the effect of disruption on train service and provides solutions for running, diversion, cancellation, or regulation of train services
• The system can show schedule time and actual time in the same graph with different colors
• The system can show mainline trains, suburban trains, goods trains, and special trains in different colors
• On clicking/selecting a particular train graph, it gives complete information about train details, including train number, crew information, and rake details
• Advance charting: the system can prepare a train graph showing predictive movements of available trains in a particular section in different colors
• It is possible to edit the timetable graphically from the train graph display by drag and drop operations
• The timetable software automatically performs reforecasting of future train trips when modifications are made by the operator or due to traffic perturbations
• The train distance graph highlights traffic conflicts and assists the regulator in identifying and implementing solutions to resolve conflict situations

Simulation Studies on Simulation Terminal

• A separate terminal is provided for simulation studies and training purposes
• The replay of log, time table editing, and editing of train graph are provided on this terminal

Time Table Builder and Editing

• Time table builder, an offline software, prepares a time table based on infrastructure data, such as signal distances, permitted train speeds, signal interlocking, and track circuit lengths
• The time table can be modified/edited offline and loaded on the TDS system

Block Working Operation

• Block operation for EI stations is done through the CTC controller from OCC
• Suitable failsafe provision of inbuilt block operation system in EI is needed for this
• For PI/RRI stations, operation of block instruments/block panel may be required to be done by SM at the station

Management Information System (MIS)

• MIS reports include:
  • Various train control charts
  • Punctuality reports
  • Actual rake link report
  • Rake composition report
  • Rake maintenance/overhauling reports
  • Analytical reports of unusual occurrences, such as signal failures, OHE breakdown, rake failure, etc.
• Train graph is available on specified terminals, showing historical train graph for analysis
• System detects conflicts like:
  • Usage of the same platform
  • Usage of the same routes
  • Usage of incompatible routes
  • Usage of the same section and same directions
  • Usage of the same section and opposite directions
• In case of conflicts, TMS displays a specific icon on the train graph and generates a solution for rescheduling involved activities

TCAS (Train Collision Avoidance System)

• Three levels of brake commands in TCAS: Normal brake command, Service brake command, and Emergency brake command
• Simulated Braking Distance Calculations for service and emergency brakes are provided in Annexure: 13-A1

Driver Machine Interface (DMI) of TCAS

• A typical overall view of DMI is shown, with features such as:
  • Real-time display of the aspect of approaching signal
  • Assistance to Loco Pilots by means of real-time display

Traffic Management System (TMS)

• TMS carries out the following functions:
  • Centralized Operation of Signalling Systems
  • Centralized Real-time Monitoring of Train Traffic
  • Interfacing and real-time data sharing with COA, Crew management system, PA system at station, ATP, etc.
  • Automatic route setting (ARS), Long route setting, and Route stacking command
  • Generation of various MIS reports, train graphs, and detection and management of alarms and logs

TCAS Features

• Based on inputs received from Signalling interlocking, the Stationary unit of TCAS generates Movement Authority which is transmitted to the train via radio
• TCAS provides bi-directional track-train communication
• Train movements are supervised continually by the Stationary unit in its territory
• The Stationary unit knows each TCAS controlled train individually by the identity of its leading TCAS on-board equipment
• Movement authority is transmitted to the vehicle continuously via UHF/GSMR/LTE radio together with speed information and track description data

Safety Concerns

• Two major areas of safety concern are:
  • LC gate Accidents
  • Signal Passing at Danger (SPAD)
• TCAS is intended to provide train protection by addressing:
  • Prevention of collisions
  • Control of speed at tracks having speed restrictions

ATP (Automatic Train Protection) Features of IRATP

• Detection and Prevention of SPAD
• Cab signalling with Display of movement authority, target distance, speed, and signal aspect
• Continuous train control
• Protection for speed restriction
• Detection of roll back
• Blowing horn while approaching Level Crossing Gate

Train Collision Avoidance Features

• Head-On Collision prevention
• Rear End Collision prevention
• Side Collision prevention

Track-side Equipment of IRATP

• RFID Tag
• Stationary unit
• Radio

On-board Equipment of IRATP

• On-Board Computer (OBC)
• RFID readers
• Driver Machine Interface (DMI)
• Loco Radio Unit
• Pulse Generators (Speed Sensors)
• Train Interface Unit (TIU)
• Interface to existing brake control system
• Power supply arrangement
• Isolation arrangement

This quiz covers the technical aspects of railway signalling systems, including trackside signals, Line Side Electronics Units, and movement authority transmission. It also touches on the integration of signalling systems with other rail systems.