Seminar Report On ACD i.e. Anti collision Devices by Tarun khnaeja ( 09034406598)

1. A
Seminar Report On
Anti Collision Device
(ACD)
Submitted to: Submitted by:
Er. Nidhi Uppal Tarun Khaneja
2110045
ECE
Department of Electronics & Communication Engineering
Doon Valley Institute of Engineering & Technology
Karnal- Haryana
(March - 2014)

2. Introduction:
The ACD Network is a Train Collision prevention system invented by Rajaram Bojji and
patented by Konkan Railway Corporation Limited (A Public Sector Undertaking of Ministry
of Railways, Government of India). ACDs have knowledge embedded intelligence. They take
inputs from GPS satellite system for position updates and network among themselves for
exchanging information using their data radio modems to take decisions for timely auto-
application of brakes to prevent dangerous 'collisions', thus forming a 'Raksha KavachTM
'
(meaning a '(Train) Safety shield').
ACDs fitted (both in Locomotive and Guard's Van of a train) act as a watchdog in the dark as
they constantly remain in lookout for other train bound ACDs, within the braking distance
required for their relative speeds. They communicate through their radios and identify each
other. If they happen to find themselves on the same track and coming closer to each other,
they automatically restrain and stop each other, thereby preventing dangerous head-
on and rear-end collisions.
Loco ACD of a train also applies brakes to reduce the train speed either to 15 km/h if on
approach it receives a message from other train bound ACD that has stopped in a block
section on adjacent track (and driver of that train has yet not communicated that things are
'Normal') or to bring the train to a stop if train bound ACDs of other train are radiating 'train
parted' message thereby preventing dangerous side collision that may occur due to
infringement of adjacent track by a stopped or a 'parted' train, respectively.
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
it.
ACD trials have recently been concluded successfully in Southern Railway. Further
implementation on Indian Railway is awaited.

3. 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 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 any of the intervention to the driver.

4. Working Of ACD
‘ACD Network’ consists of mobile ACDs (on Locomotives and Guard’s Brake Vans) and
trackside ACDs (at Stations, Level Crossings, Locosheds, Sensors based and Repeaters, en-
route). Mobile ACDs take inputs from GPS satellite system for position updates and network
with track-side ACDs located within a radius of Three Kms (using UHF radio modems); to
activate brake(s) with the help of on-board Loco ACD(s) through their Automatic Braking
Units (ABUs), whenever a collision-like situation is ‘perceived’.
Fig.1 ACD At Locomotive Of The Train
‘ACD Network’ is likely to prevent ‘head-on’ and ‘rear-end’ collisions in mid-sections,
collisions at ‘high speed’ in ‘station area’, ‘side collisions’ with derailed vehicles obstructing
adjacent line, collisions due to ‘train parting / jumbling’ and collisions with ‘road vehicles’ at
level crossing through ‘Train Approach’ warning and detection of ‘Gate Open’. Loco ACDs
also give ‘Station Approach’ warning to drivers. Moreover, using Manual ‘SOS’ buttons on

5. their ACDs, Drivers, Guards and Station Masters can also ‘stop’ trains when any unusual is
detected.
Fig.2 Anti Collision Devices
Fig.3 Konkan railway Corporation limited (A PSU of ministry of Railways)

6. Benefits of the ACD system
1. Very economical and cost effective.
2. Easily adaptable and expandable.
3. Does not degrade the existing safety level.
4. Employs state-of-art hardware and software technology.
5. No way had side equipment required, hence no requirement of Power
.
6. No cabling on the track required (which is more expensive and cumbersome).
7. Less susceptible to Vandalism.
8. It does not require any inputs to be fed by the crew at the start of journey, thus human error
is eliminated.
9. Maintenance Support System (MSS)
10. Daily Reports of incidences of Warning to the Driver due to Gate OPEN or Obstruction.
11. Date wise Report of incidences of Warning to the Driver due to Gate OPEN or
Obstruction.
12. Daily Maintenance Report of Failure of Loco Unit and Gate Unit.
13. Date wise Maintenance Report of Failure of Loco Unit and Gate Unit.

7. 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 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.

8. 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.
Future Scope of ACD
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 signalling system.