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ANTI-COLLISION DEVICE NETWORK
Chapter 1
INTRODUCTION
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 project 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
Department Of Mechanical Engineering, T. John Institute Of Technology, Bangalore-83 Page 1
ANTI-COLLISION DEVICE NETWORK
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 project 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.
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ANTI-COLLISION DEVICE NETWORK
Chapter 2
NEED OF A.C.D
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
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ANTI-COLLISION DEVICE NETWORK
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.
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ANTI-COLLISION DEVICE NETWORK
Chapter 3
Features of ACD
The principal 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
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ANTI-COLLISION DEVICE NETWORK
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
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ANTI-COLLISION DEVICE NETWORK
Chapter 4
TECHNOLOGY USED IN ACDS
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.”
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ANTI-COLLISION DEVICE NETWORK
4.1 THE WORKING OF ANTI COLLISION DEVICES
(ACDS) IN INDIAN RAILWAYS IS DESCRIBED AS
The loco a.c.d is the heart of a.c.d network. In the a.c.d the radio single from the
consolation of Global Positioning System (G.P.S) satellite or received by GPS receiver
through by 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 as 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 processed the data and generated the commend 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 received the information being send by other acd range within range 3 Km. this
information also send to the C.C.U. for processing all 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 received the data from the satellite and radio trans receiver communicate with the
other GPS. Within range of 3.Km. the tracks side and sates nary module. Such as :-
station ACD, level crossing ACD, and loco side ACD.
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ANTI-COLLISION DEVICE NETWORK
Both mobile and stationary ACD exchange information and take decision base on
trans working rule. And embedded soft ware to a apply breaks automatic with art any
input users. All the ACD work on the principle of distributed control system. It’s very
simply but it two ACD on locomotive within pre define distance and proceed and risks on
collision system. Automatically active the breaking to the train and prevent collision relay
in accident.
Unit for Locomotive ( L:- 435 x, W:- 203 x, H:- 342 mm )
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ANTI-COLLISION DEVICE NETWORK
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ANTI-COLLISION DEVICE NETWORK
4.2 THE FOLLOWING ACCIDENTS ARE PREVENTED BY
ACD
Detection and Prevention of Head-on, Rear-end and Side Collisions: – Only
system in the world to provide these UNIQUE features even when a train is not
protected by a signal, as in a block section.
Detection of fouling and prevention of collision due to fouling:- Except when
a Train on main line overshoots the ‘Fouling Mark’
Detection & generation of Train parting / Jumbling: - Consequently bringing
any approaching train on the adjoining line to a dead stop.
Station Approach Warning to Drivers: - Can result in saving of Manpower for
deployment of detonators during foggy weather, Provided 100% coverage of ACD
fitted trains is available on the
Concerned ACD route.
Speed limit imposition:- Based on ‘preset’ conditions in FRS of ACD
‘Train Approach’ Warning for road users at Level Crossings both manned
and unmanned :- In addition, at manned non-interlocked level crossings,
reducing the train speed to 30 Kmph in case the gate is detected in ‘open’
condition through Gate ACD.
Manual SOS functionality available for Drivers, Guards and Station
Masters: - To bring all trains to a halt within a radial distance of 3 Kms, in
emergencies
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ANTI-COLLISION DEVICE NETWORK
4.3 THE SITUATIONS IN WHICH ACD NETWORK CAN’T
PREVENT A TRAIN COLLISION
An analysis of ‘preventable’ and ‘non-preventable’ accidents by Safety
Directorate of Railway Board of a total of ‘128 train collisions on Indian Railways’
during the five years period namely, from April 1997 to January 2002, indicated that 82%
of these collisions were preventable by ACD. The balance 18% of the collisions were
‘non-preventable’ in any case due to various reasons like failure of brake power of train,
inadequate reaction time, insufficient braking distance, etc.
Various collisions/situations which are not preventable in any case, with or without
ACD network, are enumerated below:
Other train is a ‘NON’ ACD Train – ACD functions by reacting to another
ACD, as such if one of the two trains is a non-ACD train, the protection against
collision will be missing.
‘Adequate’ braking distance at that speed is not available when a
‘dangerous’ collision-like situation arises suddenly – However, severity of the
collision would be reduced as a function of the reaction time.
Train derails and its wagons/coaches dash with another Train, already on
‘adjacent’ track – No reaction time situation
‘Failure’ of brake power of the Locomotive/train
Rolling backward/forward of a ‘Stabled load’
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ANTI-COLLISION DEVICE NETWORK
Chapter 5
BENEFITS OF THE ACD SYSTEM
Very economical and cost effective.
Easily adaptable and expandable.
Does not degrade the existing safety level.
Employs state-of-art hardware and software technology.
No way had side equipment required, hence no requirement of Power.
No cabling on the track required (which is more expensive and cumbersome).
Less susceptible to Vandalism.
It does not require any inputs to be fed by the crew at the start of journey, thus
human error is eliminated.
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ANTI-COLLISION DEVICE NETWORK
Chapter 6
MAINTENANCE SUPPORT SYSTEM (MSS)
Daily Reports of incidences of Warning to the Driver due to Gate OPEN or
Obstruction.
Date wise Report of incidences of Warning to the Driver due to Gate OPEN or
Obstruction.
Daily Maintenance Report – Failure of Loco Unit and Gate Unit.
Date wise Maintenance Report – Failure of Loco Unit and Gate Unit.
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ANTI-COLLISION DEVICE NETWORK
Chapter 7
APPLICATIONS
ACDs can be implemented in railways to prevent collisions and to decrease the
timing between two consecutive trains running one after another.
It can be used in heavy vehicles like cranes, earthmovers etc to prevent accidents
and for their safe working in public places.
ACDs can be used as a tracking device.
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ANTI-COLLISION DEVICE NETWORK
Chapter 8
CONCLUSION
ACD is used as a watchdog as they constantly remain in lookout for other train in
bound with ACDs. ACDs can prevent the side collision that may occur due to
infringement of adjacent track by a stopped or a 'parted' train, respectively. Since it is
very economical and cost effective it can be used in all type of trains. By using ACDs a
lot of collision can come to hault and hence can save life of many human being.ACDs can
be used as Tracking device so that it can find the exact position of the obstruction ahead
and decrease the speed of the train depending upon the distance between them.
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ANTI-COLLISION DEVICE NETWORK
REFERENCES
www.google.com
www.konkanrailways.gov.in
www.rediff.com/anti_collision_devices.html
www.ask.com
www.hindustantimes.com/acd.html
www.wikipedia.org
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