ACD-Anti Collision Device Network123 - Copy

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


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.



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



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.



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



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



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.”



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.



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 )



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



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’



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.



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.



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.



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.



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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