TPWS or ACD ; the debate .

Please read the following News Items/ Criticism regarding non/ slow adoption of ACD and apparent preference for other established systems like TPWS (Train Protection Warning system) or ETCS/ERTMS on Indian Railways :

Rail anti-collision tech: Does the foreign TPWS trump the home-grown ACD?
April 26, 2010 06:14 PM
ACD

The Indian Railways has once again chosen an expensive foreign technology (TPWS) over India’s own patented ACD system

The Indian Railways recently decided to adopt the European technology Train Protection Warning System (TPWS) on busy rail routes to avoid collisions. However, the government has once again ignored the indigenous & cost-effective anti-collision device (ACD) system developed by the Konkan Railway and has instead opted for an expensive foreign technology.

According to industry experts, TPWS is not only expensive, but also less efficient compared to the ACD system. Rajaram Bojji, inventor of the ACD technology and former managing director, Konkan Railway, has also written to the railway minister on this issue.

In his letter addressed to the minister, he has stated, “You have chosen to approve more expensive systems which do not provide the protection against collisions as widely as ACD can provide. You are ill-advised.”

Commenting on the features of the TPWS, a senior railway ministry official was quoted in a news report as stating, “If the train jumps the red signal, then brakes will be applied automatically under the TPWS system. A majority of the recent accidents took place due to trains jumping red signals in foggy conditions.”

The TPWS is estimated to cost Rs70 lakh per km, and will be implemented over an 828-km rail stretch. The total cost for installing the TPWS would be about Rs579.60 crore. On the other hand, the ACD will provide a more efficient and cheaper overall protection against collisions.

ACD, which is a no-signal equipment, has superior wide-area safety-enhancing capability, while costing much less individually.

The signal department of the Indian Railways demands a Safety Integrity Level (SIL) certification for ACDs. However, Mr Bojji stated, “ACD, actually not being signal equipment, but only an additional layer, does not need SIL certification, this was confirmed by TUV Germany too in their report for assessing the ACD.”

YET ANOTHER

Railways are planned to adopt Train Protection and Warning System (TPWS)

Sep 16th, 2009 by affroze

It has been planned to adopt Train Protection and Warning System (TPWS), a variant of Auxiliary Warning System (AWS), to further enhance safety levels in train operations by preventing cases of ‘Signal Passed at Danger’ in 280 Track kilometres of ‘A’ route on Southern and North Central Railway, on trial basis.

Functionality wise there is no difference between the two systems, which are basically meant to prevent driver passing signal at danger. However, both the systems use different technologies to achieve the intended functionality.

The conventional AWA system uses track magnet, which are basically made of Copper, as track device making it prone to thefts. Information about signal aspect, in AWS, is transmitted from track device to cab equipment through electro magnetic induction.

TPWS use Euro Balise as a track device, which is an electronic device with very less copper inside and it uses radio transmission for sending information to cab equipment.

TPWS is basically meant to prevent driver from passing a signal at danger thereby preventing accident thereof. The system does not have any functionality, which can curtail outside interference of rail installation, such as track and signal equipment.

The IRSSE opinion on the Technological Choices …

MUCH ADO ABOUT NOTHING ? YOU DECIDE…..

It is surprising that the very basic flaw (or the this author perceives as an Engineer) is that ACD is a Technology TOTALLY based on GPS (or Global Positioning system) which is based on a US Govt controlled satellite system. Indian Railways never opted for satellite based systems for anything having safety or operational ramifications. GPS access can be suddenly denied by US Govt in a Hostile situation or any Technical failure or a shift to different Technology by them for their Strategic / Business reasons can put entire Indian Rail Network safety in a great jeopardy.

Also the chance of neighboring enemy Powers trying to jam GPS radio signals in a war like situation. More over it is Essential that any systems that controls train movement shall be closely linked with the existing Rail Signalling Systems which have gone through rigid safety standards (such as SIL reqmts).

Obviously Railway safety is not about Gadgetry but a serious professional strategic realm of Public Interest..

ANOTHER VIEW ON TPWS

TPWS

2 comments on “TPWS or ACD ; the debate .”

Expert comments by SANDEEP PATALAY’

Analysis of Failures of Solid State Interlocking Systems
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1. Lack of domain Knowledge in Signalling and Traditional Route Relay interlocking Systems, This creates a technological gap between the software programmers and the Domain consultants. This leads to Errors in software, which might lead to unsafe failures of the system

2.Increasing the complexity of the System by Employing distributed architecture, which is difficult to validate and verify and difficult to maintain, thus leading to very high time repair

3. Extending the working scope of the Interlocking systems for monitoring and other non-Interlocking functions, which leads to degraded performance of the system

4. Employing Non-Formal Interlocking principles instead of traditional RRI Principles leads to software complexity. For Ex: The Geographical method needs every system that is installed for new Yard needs validation, which is not practicable.

5. Since the software and hardware is so complex, complete test of the system is not possible and most of the faults are revealed at the field Installation stage or during normal working of the system in field.
The software is to be changed for every yard , the software structure should be in a generic form, but we seldom see a generic form and this the stage errors creep in.
6. The lack of standardization in the railway working principles and the core Interlocking principles, the software developers are forced to do changes in the software for every yard in Different railway zones, this is the time that errors in the software creep in.

7. Because of the above said reasons the Interlocking systems have failed to create the necessary confidence in the railway operators. Because of this reason the Solid state Interlocking systems have become unpopular.

If we examine broadly the reasons for failure and lack of reliability and maintainability that are forced by the designers are as follows:

1. Lack of standardization of interlocking principles, every railway zone has its own set of rules and principles which are conflicting with other railways, this makes the life of the developers difficult because they have change their systems settings and software accordingly.

2. There is no standard book or reference available describing the core interlocking principles, since these rules are only known by the people working in this domain.

3. Increase in the complexity of the software leads to difficulty in testing, since most of the Interlocking systems are sequential machines they are error prone are very difficult to test.

Electronic interlocking (EI) as such is not a bad word on many Zones of IR with SCR being on the fore front. Microlock-II and Westrace system near Vijayawada have been found to be fairly reliable though there had been some issues with the Czec AZD Praha systems installed on Secunderbad Division of SCR. The Siemens EI at Mehaboobnagar of Hyderabad division also has been doing well.

The Manufacturers can do better by training Railwaymen about application software so that alterations can be done” in house” for minor yard changes et all..