The present invention relates to an Integrated Train Protection System used for Railway. Railways have been the engine of economic and technical growth and development in many countries. In India, Railways are the backbone of the country's economy and an integral part of the social fabric. It is one of the largest rail networks in the world. Unlike developed countries, Indian Railways operate under vastly challenging circumstances of over crowding, low cost of travel, longer trains etc. Whilst travel by rail is amongst the safest of all forms of transport, it is a regrettable fact that railway accidents do happen and when the loss of life and property is significant. But Railway Safety is not merely an area of national concern but also poses challenges to the engineering and research community of the country. Hence a lot of attention is given to methods by which modern technologies of monitoring, control, communications, design, electronics and materials for Railway Safety are harnessed, in order to avoid future loss of life and injury during rail travel.

In view of the above a lot of efforts have been made by our in house R&D to develop state-of-the-art safety systems to prevent accidents, by utilizing technologies defined by the needs of the Rail operation.

Prior Art

Anti Collision Device (ACD) of Indian Patent 198166 dated 24th Sep 1999 is a Collision Avoidance System that has been developed for Indian Railways. Reference is also made to US Patent No. 11982774 filed on 5th November2007 and US Patent No11111692 filed on 13th Jan 2003.The ACD works on the principle of track identification and application of brakes in case of two trains occupying the same track. ACD takes GPS input for track identification. In brief " it is an Anti- Collision Device System for trains and the like transportation systems comprising of a Network of Anti Collision Devices (ACD). Provided at locomotive (LOCO ACD), guard vans (GUARD ACD) stations (STATION ACD) and level crossing gates (GATE ACD) comprising of a microprocessor based Central Control Unit (CCU), Radio Transceiver, Global positioning System (GPS) receiver, Power Converter, Data entry key pad, Whip antenna for radio transceiver and hard mount antenna for GPS receiver, a Crew interface, Automatic Braking Unit (ABU) linked with the braking mechanism of locomotive to control the speed of train as per command received from the CCU (I) all units and system functionally interconnected to detect situations when collision or side collision of two moving ACDs may occur and take quick action to prevent the same or drastically reduce the seriousness of impact by cutting down speed, independent of all types of signaling and inter locking systems and human failure". The shortcomings of the above referred Anti Collision Device are as under: -

• ACD is reliant on GPS for track identification. The GPS readings for industrial applications have an accuracy of +/- 100 meters. Two tracks in a railway network are separated by about 5 meters. For exact track identification an accuracy of +/- 3 meters is required from the GPS reading. Due to the current inaccuracies in the GPS readings the track identification in ACD has been found to be erroneous. This is more evident in multi-track sections like in a station. This has resulted in spurious brake application leading to decrease in line capacities and disruption in train operations. ACD also does not meet the requisite Safety Integrity Levels desired of such systems.

A patent application for Anti Collision System of US Patent No. 12550459 filed on 31st August 2009 discloses an anti-collision system and method for railed vehicles. This system includes a camera module, a processor and a transceiver. The camera module is configured to record images of the environment around a first railed vehicle. The processor is configured to receive an image from the camera and extract a detected feature from the image. The detected feature is then compared to features stored in a database having an associated unique location on the rail system. Should the detected feature be found with the database, the unique location on the rail system is transmitted via a transmitter as the present location of the railed vehicle. Shortcomings in Anti Collision System for Railways are as under:-

• The Anti Collision System for Railways relies on comparing images taken by the on-board camera module with the image database to determine the location information. Hence any changes in terrain will lead to non identification of the location using the above method.

• Further image comparison is a highly process intensive activity. Image comparison consumes a lot of time to deduce the location identification.

This approach will not work reliably especially in the station sections, wherein the time available to detect an imminent collision is very minimal.

• Further the Anti Collision System for Railways does not prevent side collisions and rear end collsions as the camera module is mounted on the first vehicle of the railed vehicle.

• Further the Anti Collision System for Railways does not prevent Signal Passing At Danger.

Another prior art safety system followed is the Train Protection and Warning System (TPWS). This is based on the concept of European Train Control Systems (ETCS) Level I. TPWS concept works on prevention of Signal Passing at Danger (SPAD), i.e. preventing overshoot or disregard of RED aspect of a signal and preventing violation of prescribed speed limits for trains. TPWS works on the principle of providing "Movement Authority" information to the on-board systems on a locomotive. The "Movement Authority" constitutes:

1. Aspect information of the next signal
2. Permanent Speed restrictions to be adhered to by the locomotive
3. Temporary Speed restrictions to be adhered to by the locomotive

The "Movement Authority" information is passed on to the on-board systems by track-side equipments. The track side equipment comprise of Line side electronic Units and on track Balises. Shortcomings of these TPWS are as under:-

• TPWS is reliant on the signaling system for prevention of SPAD. In case of failure of the signaling system, TPWS would not be in a position to prevent collisions if two trains are found to be on the same track.

• TPWS also cannot work reliably in Automatic Block Sections of the Railway network. In an Automatic Block Section the locomotive pilot has an authority to proceed in a restricted speed even if the signal ahead indicates RED aspect. Any human error when exercising these discretionary powers vested in the locomotive pilot might lead to collisions.

Yet another prior art railway safety system is Railway Anti Collision Apparatus and Method is given in US Patent number 4864306 filed on 23rd June 1986. A Railway Anti Collision Apparatus and Method is disclosed in which machine readable trackside markers such as bar code markers are utilized along the track and are read by apparatus onboard the train to provide track number identification, milepost identification and train detection. Onboard the train is equipment to provide train identification and train speed. This information is transmitted through transponders between trains and to a central station and is processed by apparatus onboard the respective trains and central location to provide visual and audible signals indicative of a potential train collision. The shortcomings of these systems are as under:-

• While the Railway Anti Collision Apparatus provides means for train identification and visual and audible warnings in potential train collision scenarios the Apparatus does not provide automatic braking in cases of loco pilot negligence to heed to the warnings and apply brakes.

• Further the Apparatus does not provide prevention of Signal Passing At Danger.

Background
Hence a need is felt for a comprehensive solution that offers both Collision Avoidance and Train Protection features for using in Railways. Existing Solutions offer either Collision Avoidance or Train Protection, but not both. The technologies used by existing Collision Avoidance systems are not yielding reliable results. The existing Collision Avoidance systems do not meet the Safety Integrity Levels required for such systems.

Existing Train Protection Systems are Signaling dependent systems and do not prevent Collisions in case of failure of the Signaling system. The existing Train Protection systems are also un-reliable in Automatic Block sections in a Railway network.

The primary objective of this invention is to provide comprehensive collision prevention i.e prevention of head-on collisions, rear-end collisions and side on collisions.

Further objective of this invention is to provide Speed Control by automatic application of brakes in case the locomotive exceeds the allowable speed limit.

Further objective of this invention is to meet the highest Safety Integrity Level (SIL) of SIL4.

Another objective of this invention is to provide reliable track identification mechanism by usage of On-Track Beacons.

Yet another objective of this invention is to use signaling inputs for adding reliability to deduce track identity in the station section.

Another objective of this invention is to prevent Signal Passing at Danger.

Yet another objective of this invention is to provide scalability to Cab Signaling.

Still yet another objective of this invention is to integrate with Train Management Systems.

Further objective of this invention is to provide scalability for Centralized Train Management.

Summary of Invention
Integrated Train Protection System - ITPS is a comprehensive Collision Prevention and Train Protection System. ITPS uses On-Track beacons for track identification which would enable the system to detect presence of two trains on the same track and ensure application of brakes to prevent collision. Traditionally on-track equipment like Balises used for TPWS is mounted on the sleepers of railway track. This arrangement makes the equipment susceptible to theft. Also there are possibilities of un-desirable material getting deposited on to the on-track equipment degrading the functionality. To prevent theft and to ensure that the On-track Beacons are not exposed to undesirable elements, the On-Track Beacons in ITPS would be embedded in to the sleepers of the track. This would require specialized sleepers that are similar that of the same dimensions of the regular sleepers, but these specialized would have housing mechanism for embedding the On-track Beacons. The on-board system of ITPS would receive aspect and speed information from the Radio Control Center. When the aspect of the signal is "RED", the on-board system of ITPS would apply brakes, if the driver is not responding to the "RED" aspect of the signal. The on-board system also receives the permissible speed limits for the locomotive from the Radio Control Center. The on-board equipment compares this information with the actual speed of the locomotive and reduces the speed of the locomotive by application of brakes to bring the speed of the locomotive to permissible limits.

ITPS does not just combine functionalities of existing ACD and TPWS, but ensures safety and reliability needed for passenger transport and also ensures scalability to provide CAB signaling and Centralized Train Control that existing systems do not offer. Further ITPS is designed to integrate with Train Management Systems.

List of essential features under our invention can be summarized as under:-

• Collision Prevention (Head On, Rear-end, Side-on)
• Prevention of Signal Passing at Danger
• Train Integrity Check (Detection of Train Parting)
• EMERGENCY Alerts for unusual stoppage of trains
• Speed Control to prevent Over speeding of trains
• Use of On-track beacons for reliable track identification
• User Friendly Driver Machine Interface (DMI)
• Radio Control Center at Stations for communicating Signal and Permissible Speed information to the on-board systems

According to our invention an Integrated Train Protection System ( ITPS ) comprising a) On-Track beacons for track identification to enable the system to detect presence of two trains on the same track and to ensure application of brakes to prevent collision; b) On-board System consisting of a Micro-Processor based On-board Computer (OBC) with Power Supply module Micro-Processor based Driver Machine Interface (DMI) GPS module Micro Processor Radio Interface Unit Braking Interface Unit Beacon Reader and Speed Sensor Unit c) Radio Control Center consisting of a Micro-Controller based Signal Interface Unit with Power Supply module a Micro-Processor based Signal Processor Unit with Power Supply module, and a Micro-Processor based Radio Interface unit with Power Supply module; wherein the said on-board system is capable of receiving aspect location and speed information from the respective module/ unit and taking appropriate action for applying brakes, if the driver is not responding to the "RED" aspect of the signal and also capable of receiving and comparing the permissible speed limits for the locomotive from the Radio Control Center with the actual speed of the locomotive and reduces the speed of the locomotive by application of brakes to bring the speed of the locomotive to permissible limits.
Now the invention will be described in more detail with reference to the accompanying drawings bringing out a preferred embodiment of the arrangement according to the invention in which figures and descriptions are given as under:

Fig 1 : Block Diagram of the On-board system

Wherein

1. GPS module
2. Speed Sensor Unit
3. Driver Machine Interface
4. Microprocessor Radio Interface Unit
5. Beacon Reader
6. DC Power Supply module
7. Braking Interface Unit
8. On Board Computer
8a. Micro-Controller 8b. RAM
8c. Flash Memory
8d. Power Supply

Fig 2: Block Diagram of the Radio Control Center Wherein

9. Signal Interface Unit with Power Supply Module 9a. Micro-Controller
9b. RAM
9c. Flash Memory
9d. Power Supply
9e. Battery and Charger
9f. AC Mains interface
9g. Signal interface
10. Signal Processor Unit with power supply module
10a. Micro-Controller
10b. RAM
10c. Flash Memory
10d. Power Supply
10e. Battery and Charger
10f. AC Main interface
11. Radio Interface unit with power supply module

Fig 3: Deployment Diagram of On-track Beacons in a Block Section Wherein

12. On-track Beacons at entry and exit of Station Section 12a. Block Section

Fig 4: Deployment Diagram of On-track Beacons in a Station Section Wherein

13. On-track Beacons in Station Section 13a. Station Section

Fig 5: ITPS Architecture Diagram Wherein

14. Radio Control Center

15. On-board System

16. GPS inputs

17. On-board System on Guard or last vehicle

18. Radio Communication between On-board System and Radio Control Center

The On-board system of ITPS comprises of:

• Micro-Processor based On-board Computer [8] consisting of Microprocessor [8a], RAM [8b], Flash memory 8[c], Power Supply modules 8[d] and Interfaces to GPS module, Brake Interface Unit, Speed Sensor Unit, Radio Interface Unit, Driver Machine Interface, and Beacon Reader.

• GPS module [1]
• Brake Interface Unit [7]
• Speed Sensor Unit [2]
• Micro - Processor based Radio Interface Unit [4]
• Micro - Processor based Driver Machine Interface [3]
• Beacon Reader [5]

The On-Board Computer [8] gets location and speed input from the GPS module [1], The On-board Computer [8] gets speed input from the Speed Sensor Unit [2], The On-board Computer [8] uses fusing techniques on both these inputs to arrive at an accurate speed of the locomotive. The On-board Computer [8] gets the track identification information from the Beacon Reader [5]. The Beacon Reader [5] picks up the track identification information from the On-track beacons [12] and [13] deployed on the sleepers of the track. The On-board Computer [8] gets the Signal Aspect information and the permissible speed for the locomotive transmitted by the Radio Control Center [14] through the Radio Interface Unit [4], The On-board Computer [8] sends its track identification information through the Radio Interface Unit [4] over Radio to the On-board Computers of other locomotives. The On-board Computer [8] receives track identification information of other locomotives through the Radio Interface Unit [4],

The On-board Computer compares its track identity with the track identification information of the other locomotives. Incase the On-board Computer [8] deduces that its track identity is equal to the track identification information of any other locomotive the On-board Computer [8] initiates application of brakes to prevent collision through the Brake Interface Unit [7]. The On-Board Computer [8] checks the aspect information of the Signal received from the Radio Control Center [14] through the Radio Interface Unit [4], In case the aspect of the Signal is "RED", the On-board Computer [8] alerts the locomotive pilot through the Driver Machine Interface [3]. In case the locomotive pilot does not respond to the warnings and does not initiate braking within permissible time, the On-board Computer [8] initiates braking through the Brake Interface Unit [7],

The On-board Computer [8] also compares the permissible speed information received from the Radio Control Center [14] with the actual speed of the locomotive and initiates application of the brakes to reduce the speed of the train to permissible limits.

The On-board Computer [8] in the locomotive also compares the location information of the locomotive received from the GPS module [1] and the location information of its last vehicle received through the Radio Interface Unit [4], Incase the difference between both these values is not equal to the pre-defined value and is found to increase during subsequent comparisons, the On-board Computer [8] deduces this as a case of train parting and warns the locomotive pilot through the Driver Machine Interface [3].

In case the GPS input received from the GPS module [1] remains constant for consecutive readings and the Speed Sensor Unit [2] input is zero for consecutive readings the On-board Computer [8] and the locomotive is found to be in the block section, the On-board Computer [8] sends alert messages to other locomotives through the Radio Interface Unit [4],

The Driver Machine Interface [3] is a Micro-Processor based unit that consists of a display to show warning and status messages to locomotive pilot. It also consists of indications both audio and visual to warn the locomotive pilot in case of emergencies. It also has push buttons to acknowledge the warning messages.

The Beacon Reader [5] is a Micro-Controller/Micro-Processor based unit, it is fitted in the under carriage of the locomotive. The Beacon Reader [5] also consists of an antenna/sensor to read information from the On-track Beacon [12] and [13] whenever the locomotive passes over the On-track Beacon [12] and [13].

The Radio Control Center (Fig: 2) of the ITPS comprises of
• Micro-Controller based Signal Interface Unit [9]
• Micro-Controller based Signal Processing Unit [10]
• Radio Interface Unit [11]

The Signal Interface Unit comprises Micro-Controller [9a], RAM [9b], Flash Memory [9c], Power Supply Unit [9d], Battery and Charger [9e], AC Main interface [9f] and Signal interface [9g].

The Signal Processing Unit comprises Micro-Controller [10a], RAM [10b], Flash Memory [10c], Power Supply Unit [10d], Battery and Charger [10e], AC Main interface [10f]

The Signal Interface Unit [9] takes the aspect information through the relays of the Signaling system in a fail safe manner. The Signal Interface Unit [9] passes this information to the Signal Processing Unit [10],

The Signal Processing Unit [10] processes the aspect information from the Signal Interface Unit [9] and sends this information to the On-board System [15] through the Radio Interface Unit [11],

The Radio Interface Unit [11] is a Micro-Processor based system that consists of High Frequency or Very High Frequency or Ultra High Frequency Radio Transmitter and Receiver with an external antenna.

The On-track Beacon [12] and [13] is reliable Radio Frequency identification devices that are deployed on the tracks at strategic locations. The On-track Beacons [12] and [13] are pre-programmed to contain geographical location information and track identification information. This information in the On-track Beacon [12] and [13] is read by the Beacon Reader [5] on the locomotive, whenever the locomotive passes over the On-track Beacon. The On-track Beacons are embedded in to the sleepers of the tracks to prevent theft of the devices. The On-track Beacons are deployed both in Block Sections [12a] and Station Sections [13a],

Few of the optional features under our invention are :

• Scalability to Cab Signaling
• Integration with Train Management Systems
• Scalability to Centralized Train Control

We have brought out the novel features of the invention by explaining one of the preferred embodiments under the invention enabling the man in the art to understand and visualize our invention. It is also to be understood that the invention is not limited in its application to the details set forth in the above description or illustrated in the drawings. It is be to noted that the phraseology and terminology employed herein are for the purpose of the description and should not be regarded as limiting. Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention as described herein above and as defined in the appended claims.

We claim
1. An Integrated Train Protection System ( ITPS ) comprising a) On-Track beacons [12] and [13] for track identification to enable the system to detect presence of two trains on the same track and to ensure application of brakes to prevent collision; b) On-board System consisting of a Micro- Processor based On-board Computer (OBC) [8] with Power Supply module [6], Micro-Processor based Driver Machine Interface (DMI) [3], GPS module [1]; Micro Processor Radio Interface Unit [4], Braking Interface Unit [7], Beacon Reader [5] and Speed Sensor Unit [2]; c) Radio Control Center consisting of a Micro-Controller based Signal Interface Unit with Power Supply module [9], a Micro-Processor based Signal Processor Unit with Power Supply module [10], and a Micro-Processor based Radio Interface unit with Power Supply module [11] wherein the said on-board system is capable of receiving aspect location and speed information from the respective module / unit and taking appropriate action for applying brakes, if the driver is not responding to the "RED" aspect of the signal and also capable of receiving and comparing the permissible speed limits for the locomotive from the Radio Control Center with the actual speed of the locomotive and reduces the speed of the locomotive by application of brakes to bring the speed of the locomotive to permissible limits.

2. The Integrated Train Protection System as claimed in claim 1 wherein the On-track Beacon [12] is a microprocessor based reliable Radio Frequency identification devices that are deployed on the tracks at strategic locations is capable of embedding in to the sleepers of the track and are pre¬programmed to contain geographical location information and track identification information is read by the Beacon Reader [5] on the locomotive, whenever the locomotive passes over the On-track Beacon.

3. The Integrated Train Protection System as claimed in claim 1 wherein the On-Board Computer [8] is capable of using fusing techniques on both location and speed input from the GPS module [1] and the speed input from the Speed Sensor Unit [2] to arrive at an accurate speed of the locomotive.

4. The Integrated Train Protection System as claimed in claim1 wherein the On-board Computer [8] can get the Signal Aspect information and the permissible speed for the locomotive transmitted by the Radio Control Center [14] through the Radio Interface Unit [4] and can send its track identification information over Radio to the On-board Computers of other locomotives and can compares its track identity and initiates application of brakes to prevent collision through the Brake Interface Unit [7],

5. The Integrated Train Protection System as claimed in claim 4 wherein the On-Board Computer [8] is capable of checking the aspect information of the Signal received from the Radio Control Center [14] through the Radio Interface Unit [4] and in case the aspect of the Signal is "RED", the On¬board Computer [8] alerts the locomotive pilot through the Driver Machine Interface [3] and in case the locomotive pilot does not respond to the warnings and does not initiate braking within permissible time, the On-board Computer [8] initiate braking through the Brake Interface Unit [7].

6. The Integrated Train Protection System as claimed in claim 4 wherein the On-board Computer [8] is capable of comparing the permissible speed information received from the Radio Control Center [14] with the actual speed of the locomotive and initiates application of the brakes to reduce the speed of the train to permissible limits.

7. The Integrated Train Protection System as claimed in claim 4 wherein the On-board Computer [8] in the locomotive is capable of comparing the location information of the locomotive received from the GPS module [1] and the location information of its last vehicle received through the Radio Interface Unit [4] and incase the difference between both these values is not equal to the pre-defined value and is found to increase during subsequent comparisons, the On-board Computer [8] deduces this as a case of train parting and warns the locomotive pilot through the Driver Machine Interface [3].

8. The Integrated Train Protection System as claimed in claim 1 wherein the On-board Computer [8] is capable of sending alert messages to other locomotives through the Radio Interface Unit [4] that the locomotive has made a un-scheduled halt in the block section, if the GPS input received from the GPS module [1] remains constant for consecutive readings and the Speed Sensor Unit [2] input is zero for consecutive readings.

9. The Integrated Train Protection System as claimed in claim 1 wherein the Driver Machine Interface [3] is a Micro-Processor based unit that consists of a display to show warning and status messages to locomotive pilot and also consists of indications both audio and visual to warn the locomotive pilot in case of emergencies in addition to push buttons to acknowledge the warning messages.

10. The Integrated Train Protection System as claimed in claim 1 wherein the entire system and sub-systems thereof meet the necessary Reliability, Availability, Maintainability and Safety requirements required of such systems.

11. The Integrated Train Protection System as claimed in claim 1 wherein the entire sub-systems meets the EMI and EMC requirements for On-board, on- track and track-side requirements.

12. The Integrated Train Protection System as claimed in claim 1 is capable of functioning reliably both in Electrified (RE) areas as well as non-Electrified areas of railways, in Absolute Blocks, Intermediate Blocks and Automatic Blocks of the Railway network as well as in single and multi-line sections of Railway network.

13. The Integrated Train Protection System as claimed in claim 1 to 11 substantially herein described with reference to and illustrated in figure 1 to 5 of the accompanying drawings.