ANTI COLLISION DEVICE

ANTI COLLISION DEVICE

1. INTRODUCTION

One of the most used and comfortable modes of transportation system is the train, but occasionally, accidents occur due to collisions as well as other reasons. It is very difficult to stop such collisions because of speed of moving trains, which need a lead distance to stop. Collisions happen due to human errors and/or faulty equipment.

Based on the concept and domain knowledge provided by Konkan Railway Corporation Ltd, the networked Anti-Collision system was developed which is a customized version of RAKSHA KAVACH product, using Global Positioning System, Radio Communication, and Application Logics and inter-facing these with an auto breaking system in the train, conforming to the functional requirement specifications laid by Konkan Railway Corporation Ltd.

Anti-Collision Device (ACD) is a self-acting microprocessor-based data communication device

designed and developed by Konkan Railway.

When installed on locomotives (along with an auto-braking unit - ABU), guard vans, stations

and level-crossing gates (both manned and unmanned), the network of ACD systems prevents

high-speed     collisions       in      mid-sections,      station     areas      and     at     level-crossing      gates.

The ACD uses both radio frequency and Global Positioning System (GPS) through satellites,

whereby a train is automatically brought to a halt if the track ahead is not clear. The train

starts braking 3 kms ahead of a blockade.

The Anti-Collision Device (ACD), also called `Raksha Kavach,' envisages setting up a network

of "self-acting" micro-processor based communication devices which automatically apply brakes

on trains that are unknowingly getting into a "collision-like situation," including before stations

and at mid-sections. "At the mid-sections, where neither the protection of signals nor guidance is

available to the driver, the ACD makes the loco intelligent and extends its capability to detect

any collision-like situations in a range of 3 km, which the driver cannot detect on his own.

Situations like collision between two approaching trains or between a derailed train on one track

and an approaching train on the adjacent tract can thus be prevented," according to the KRCL

official.

The "silent" network of ACD systems can be installed on the locomotives, guard vans and at

stations, which could ensure that trains do not collide at while travelling at high speeds. Further,

if the ACD systems are provided at the level crossing gates (both manned as well as un-manned),

the projects could provide protection to the lives of road users also. "We have tested the commercial prototypes of ACD system, which has been developed indigenously for the first time in the world. It has been technically proven during joint field trials with Research Design and Standards Organization, nominated by the Railways," the official said. The ACDs are capable of multi functions. For example, while approaching a station, the Loco ACD gives the "station approach" warning to the driver about 2 km in rear of the first STOP signal of the station and in case the driver ignores the warning it will automatically regulate the train speed.

The pilot projects implementation of ACD was successfully commissioned on the North-East Frontier Railway this year. Survey for expanding the system to another 10,000 km falling on the critical and busy sections of the network is almost complete. The installation of this device will go a long way in preventing collision accidents. The application of this device has been refined to not only prevent mid-section collisions but also to pre-empt their occurrence in station yards.

The newly engineered solution is integrated with the signaling systems and interlocking to react appropriately in case collision-like conditions are perceived at the time of reception and dispatch of trains from a station. The design of crash-worthy coaches and tight lock couplers with anti-climbing features has been finalized and all future coaches are being made as per the new design. Despite the phenomenal increase in traffic, the number of consequential train accidents has come down from 464 in 2000-01 to 234 in 2005-06, a reduction of almost 50 per cent. In 2006-07, the number of accidents came down to 195, the lowest-ever since the 1960s. Safety is the prime concern and all possible measures are being taken to ensure the safety of passengers.

ACD trials have recently been concluded successfully in Southern Railway. Further implementation on Indian Railway is awaited. ACD deployment has been completed successfully over 736Kms on the Konkan route and another 1730Kms on the Northeast Frontier Railway routes is nearing completion. The above routes consist of some of the most inhospitable rail sections of the country. The work involved surveys of the tracks, erection of towers, manufacturing and supply and commissioning of networked ACD system and customizing the same.

2. NEED OF ANTI COLLISION DEVICE

The main modules of the ACD includes a GPS (Global Positioning System), which picks up signals from the constellation of GPS satellites that are being exclusively used for this purpose. The GPS submits the data to the Command and Control Unit (CCU) to extract the parameters related to the movement of locomotive like latitude, longitude, speed, angle, date and time. The antenna of the GPS receiver is fitted outside on the roof of the locomotive. The user-friendly device helps the driver to know the various positions in the form of audio-visual indications, like Station Approach, SOS (for head-on, rear-end and side collision situations) and Gate Open. Another module is the radio trans-receiver, which transmits the information and commands generated by the CCU and receives the information being sent by other ACDs when the two systems are within the radio-range of 3 km.

The final module in the system is the braking mechanism, which envisages the CCU to take a decision for applying either the normal brake or the emergency brake on the locomotive as the situation required. "The electro-pneumatic braking is then applied through suitable solenoid interface installed for this purpose in the cab of the locomotive," the official explained. ACD is an intelligent friend to the engine driver, which can act on its own without any human intervention. It comprises a Command and Control Unit (CCU), a GPS Receiver, Radio Transmitter and Crew Interface. The CCU, which is the heart of the ACD, is a microprocessor-based module which processes the data and generates commands. The GPS Receiver picks up signals from GPS satellites and submits the same to the CCU to extract parameters related to the movement of the locomotive such as latitude, longitude, speed, angle, date and time. ACD prevents the head-on collision of two speeding trains, which accidentally happen to be on the same track. An ACD mounted on a train constantly looks out for signals from another ACD in a 3-km range. The moment both the trains are within the required breaking distance, the ACDs, after analysing the data from the GPS, deduce that they are on the same track and are heading for a collision. Then the ACDs automatically apply the brakes, bringing both the trains to a halt without the intervention of the driver.

The ACD can be used not only for avoiding head-on collisions but also to detect if a train has

accidentally stopped on the same track as another, preventing a following train telescoping into its rear. Also, if two trains are moving on the same track but the separation distance is less than 2 km, the ACD will automatically regulate the following train's speed. It can also detect when the bogies of a train from an adjacent track derail on to a train's path. Konkan Railways has tested out 11 accident scenarios with the ACD.

The ACD can be mounted not only on trains but also be installed at railway stations, level crossing gates (both manned and unmanned), and on guard vans. If a station is equipped with an ACD, the driver will receive the ``station approach'' warning as the train approaches the station. Also, the ACD can sense whether a level crossing gate is open or damaged and warn the driver, besides regulating the train's speed.

Fig 2.1:A moving train rammed into a stationary one at Santhia in West Bengal, killing more than 60 people.

Fig 2.2: On September 13, the Chennai Beach-Vellore Cantonment Mainline Electrical Multiple Unit (MEMU) train rammed into the Arakkonam-Katpadi passenger from behind as it was waiting for a signal at Sitheri Station, about 90 kms from Chennai, killing ten people.

3. FEATURES OF ANTI COLLISION DEVICE

The principle object of the present invention is to overcome these disadvantages and provide an anti-collision safety device for vehicles travelling on tracks, without any driving personnel, that is to say, a device which itself can estimate risks and react in consequence. More generally, the invention is intended to provide a device comprising means of observation and making decisions for safe operation, using in particular the principle of deformable movable blocks. To this end, the present invention relates to an anti-collision safety device of the type indicated above, characterized in that it comprises means for detecting and counting reference points provided along the track, means for calculating the distance of a vehicle from a given zero point, and means for converting this distance into a time with a time reference constituted by a synchronization pulse received by all the vehicles. The device further comprises means for generating a series of position pulses, emitted by all the vehicles and received by all the vehicles, the distance between a vehicle and the vehicle immediately preceding it being determined by comparing the position pulses; further, the safety device of each vehicle compares this relative distance with its stopping distance and causes the vehicle to stop when the relative distance is smaller than the stopping distance.

According to another characteristic feature of the invention, the stopping distance is determined from the actual speed of the vehicle, which may be obtained by a tachometer (e.g., a phonic wheel) supplying speed signals to a function generator which is initialized by the position pulse and which furnishes an output signal as soon as the function generator has reached the actual vehicle speed, the vehicle being caused to stop if the signal from the function generator does not lie within the distance between the vehicle and the vehicle immediately preceding it (relative distance window).

According to another characteristic feature of the invention, an alarm is given by a position alarm device set off separately or in combination by a breakdown of the reference point detector, a beakdown of the reference point counter, or a transmission breakdown. This alarm is transmitted to the central control station (PCC) by the emission of a pulse characteristic of a vehicle, and the

central station PCC then distributes a general brake or line emergency stop signal that stops all vehicles on the line.

According to another characteristic feature of the invention, the safe operation of the loop functions (calculaton of position, calculation of stopping distance) is controlled by the signals supplied by duplicate breakdown detecting circuits, the output signals from the means checking for intrinsic safety the coincidence of the output signals of the duplicate circuits, the absence of coincidence characterizing a breakdown or a risk of collision and causing stopping

4.TECHNOLOGY USED IN ANTI COLLISION DEVICE

The heart of the ACD is an Intel 80386 processor that uses the DM&P M617 Intel chipset. It [ACD] has an integrated digital radio modem and works on the VxWorks Real Time Operating System (RTOS). Raja ram adds, VxWorks, as a platform, is most suitable for real-time applications.

5. THE WORKING OF ANTI COLLISION DEVICES (ACDS) IN

INDIAN RAILWAYS

The loco ACD is the heart of ACD network. In the ACD the radio signal from the consolation of Global Positioning System (G.P.S) satellite are received by GPS receiver through antenna. This signal is sent to the command and control unit that is C.C.U. of the ACD.The C.C.U is micro processor based module. And acts like a brain of the ACD system.

The GPS submits the data to the Command and Control Unit (CCU) to extract the parameters related to the movement of locomotive like Latitude, Longitude, Speed, Angle, Date and time. It processes the data and generates the command from the ACD.A part from the GPS receiver there is a radio Trans receiver inside the ACD. A transmits information such as Identification no, Speed, Location in terms of Latitude, Longitude and status of it working with the help of sprats radio antenna. It also receives the information being send by other ACD range within range 3 Km. This information is also sent to the C.C.U. for processing or receiving the information from the other ACD and the data from the GPS receiver. The C.C.U unit take a design for apply either a normal & emergency break or the locomotive break as the case may be.

This is active with the help of the auto breaking unit of the loco on board mobile loco ACD and guard room.ACD have both a GPS receiver and radio trans receiver. The GPS receiver receives the data from the satellite and radio trans receiver communicates with the other GPS. Within range of 3.Km. The tracks side and stationary module. Such as :- station ACD, level crossing ACD, and loco side ACD.

Both mobile and stationary ACD exchange information and take decision based on trans working rule. And embedded software to apply breaks automatically with art input users. All the ACD work on the principle of distributed control system. It is very simply but it two ACD on locomotive within predefined distance, proceed and risks on collision system. Automatic brake of the train prevents the collision.

6. ADVANTAGES OF NETWORKED ANTI COLLISION DEVICE SYSTEM

^Ø Auto Acting Devices : The Networked Anti-collision system consists of aNetwork of Auto Acting Micro processor based communication devices that will trigger off automatic brakes of trains whenever a collision like situation would arise.

^Ø Designed for preventing collisions : The system is specially designed to preventcollisions at the stations, mid sections, level crossings, and parallel sections.

^Ø Provide distance scan : The system provides a distance scan over a range ofnearly 3 KMs, thereby detecting collision like situations, if any, take appropriate action to prevent collision, by constant data communication- interchange in the area.

^Ø   Communication based Control System : Through data communication, Loco

ACD in the Locomotive, Station ACD in the station, Level crossing Gate ACDs (manned as well as unmanned level crossings), are networked and are constantly in communication with each other within a range of 3 KMs. If the communication range is reduced due to obstructions, it is extended by providing Repeaters along the track.

^Ø Does not interfere with Normal Traffic  : Here  in  all  cases,  even  though

movement of train is controlled through data communications, where in standard rules are implemented to avoid collision on railroads, the ACDs do not interfere with normal operational procedures and traffic. In normal conditions, the driver is still solely responsible for the safety and control of the train, along with the guard.

^Ø   Very economical and cost effective.

^Ø   Easily adapatable and expandable.

^Ø   Very economical and cost effective.

^Ø   Easily adapatable and expandable.

^Ø   Does not degrade the existing safety level.

^Ø   No side equipment required, hence no requirement of power.

^Ø   Employs state-of-art hardware and software technology.

7. ANTI-COLLISION TRIAL OF TRAINS SUCCESSFUL

The test was conducted by running two trains, fitted with modified and most advanced TCAS technology equipment, in the opposite directions on the same track at 60 kmph and with a train coming from behind into a stationary one between Mantatti and Navandgi stations. Both the trains screeched to a halt at a distance of about 200 metres as the officials watched the moment with bated breath. Smiles broke out as the efficacy of the new technology proved in the trial. Interestingly, all the senior railway officials were sitting in the moving train which approached the stationary one from behind.

8. ANTI COLLISION DEVICE DEFICIENCIES

The ACD system is based on GPS based positioning and track detection. This had its inherent problems as with the GPS- Standard Positioning GPS service or Coarse acquisition ( Precision positioning is only available in US for military use )the best possible horizontal accuracy is 10m. This is inadequate for detection of rail tracks separated by a distance of 10–15 feet. ACD does not even have DGPS (Differential GPS that gives an accuracy close to 2.5m ) and hence had errors in track detection using their patented Deviation Count Theory that worked in block sections but failed in station sections. The result was erratic braking that disrupted train movements and proved to be ineffective. As per the CAG report the ACD is not foolproof andhas inherent deficiencies.

Another design different to ACD was patented in 2001, named "Railway Collision AvoidanceSystem" by an Indian inventor, Indranil MajumdarfromCalcutta who was awarded the TexasInstruments Analog Design Challenge 2001 for this design and the patent granted in 2007 (IndiaPatent no. 201106). The design ruled out GPS as it was a 3rd party system (US based) andsuggested track based sensors similar to RFID (Radio Frequency Identification Device) or Balise ( similar to the EuroBalise). The design didn't receive much attention as the inventor had no railway background. However, the design concepts were eventually reflected in the TCAS design first released in 2008.

After 7–8 years of problems with the ACD system, RDSO, Lucknow drafted the TCAS (Train Collision Avoidance System) specs. with amendments that followed and finally in 2012, the Ver3.1.1 spec. has been released (after joint consultation with companies manufacturing signaling equipment for the Indian Railways). The ACD system though in use with the Indian Railways, has its inherent problems in Station Sections due to its design concept of using GPS for track detection that is not viable.

The High Level Safety Review Committee meeting held in Mumbai on 12/13th January'2012 atthe Western Railway HQ, chaired by Mr. Anil Kakodkar, Metroman Mr. Sreedharan, Mr. N.Vedachalam, Mr. Sanjay Dhande and Mr. G.P. Srivastava, all eminent big wigs from Atomic Energy Commission, Railways, Space Applications centre, IIT, Kanpur and BARC were sceptic

of the ACD effectivity and were unanimous of having TCAS developed, as an open architecture system that shall offer multi-vendor operability without attracting any royalty unlike the ACD which is proprietary. ACD design details were not released to achieve multi-vendor operability.

TCAS being developed by qualified companies (RDSO approved and manufacturing railway safety systems that includes, Kernex Microsystems, Medha Servo Drives Hyderabad, Invensys Bangalore, Siemens, HBL Power Systems Ltd Hyderabad and others) in India selected by RDSO through an Expression of Interest (EOI), shall be an Indian Train Protection System offering collision avoidance and also offer many functionalities of the European Train Control System that includes prevention of Signal Passing at Danger(SPAD), Movement Authority and Control, Critical Train Data Recorder, advance incab display of signals, advance alerts and warnings from

Station sections, uploading of running train data to a Central Train Management System over GSM-GPRS,etc.

TCAS has been selected for implementation and it is going to cost very heavy to Govt as per this news report there would be a cost of 10 L INR per km.

A reliable anti-collision device (ACD) is yet to be developed so far. The ACD was not in a position to judge whether the inputs derived from the signalling systems were dependable. It also noted out that there was no system to detect whether the ACD installed in locomotives and guard vans were defective or not.

9.   APPLICATIONS

1.      ACDs can be implemented in railways to prevent collisions and to decrease the timing between two consecutive trains running one after another.

2.      It can be used in heavy vehicles like cranes, earthmovers etc to prevent accidents and for their safe working in public places.

3.      ACDs can be used as a tracking device.

10.   FUTURE SCOPE

Pilot project of "Provision of ACD Network" has been successfully commissioned recently on the Northeast Frontier Railway (of Indian Railways), covering 1736 Route km (of its Broad Gauge route). Final commissioning trials of ACD network installed on 760 km of Konkan Railway route is presently underway.

Anti Collision Device (ACD), which is an on-board train protection device and also the first ever device in the world indigenously developed by Konkan Railway with their Technical Partner Kernex Microsystems (I) Ltd, will be in place by 2013 on the entire Indian Railway network so as to reduce chances of Train collisions.

A new ACD Version-II [now called Train Collision Avoidance System (TCAS)] is under development by The Research Designs and Standards Organisation (RDSO). Unlike ACD which is more of a distributed system which acts independently, the TCAS will be more of a centralized system where in Station TCAS controls communication between locos and with locos with TDMA protocol. The TCAS under development is meant to be a vital safety system meaning TCAS have a deep coupling with Railway's signalling system where as ACD systems does not depend on Railway's

11. CONCLUSION

India is that country which has one of the largest railway networks in this world. Every single day hundreds of trains run. The people also depend on trains as it is an affordable means of transportation. The ever increasing traffic may lead to collision. Therefore Anti collision device is developed and it works successfully. The number of accidents taking place has reduced to a large extent. Even after the increase in traffic, the number of accidents has come done from 464 in 2001 to 234 in 2005-06, a reduction of almost 50 percentage. In 2006-07 the number of accidents came down to 195.