2010 Q10 Environmental factors which influence design of S&T equipment

[Hort]

Hi,
I have had a go at Q10 from last year's paper. I would welcome any comments.

[PJW]

I think this was good, particularly for the first portion. It started excellently with quite a comprehensive list of bullet points and then did the a), b) c) relatively well, although perhaps more emphasis should have been given to the differences in the various environments. For example vibration is considerably more of an issue with a tachometer on a wheel axle or a point machine bolted to the rails or incorporated into its sleepers than on other items of equipment such as level crossing mechanisms and again less of an issue for a TDM system in a trackside REB and probably hardly an issue at all for the VDU control system in a main signalling centre.

I thought it was the 2nd portion of the question which was weakest; to be honest I couldn't really find it. There was some material (which really was focussed on design features of products and site application- certainly fairly relevant but not "hit nail firmly on the head" type stuff) associated with comments on a) and b) but certainly in the answer there was no separate section at the end. Overall the answer seemed a bit short [well this is as judged as a "30 min" attempt; I accept that this was actually asked in 2010 as a 20 min question], as if you had run out of time without really getting onto that section.

If the earlier comments were supposed to be addressing the last portion of the question, then that wasn't made obvious enough. If you are going to address a question not in strict chronological order then it is particularly important to make sure the examiner will recognise that you have done that. Hence use headings or wording in your text that "echo" phrases in the question, so that the "penny drops" with the examiner.

Also whilst recognising that there are no marks for spelling it is important that the meaning is not lost. So whereas someone of my generation will grimace when they see fantom rather then phantom, there is no problem understanding what is meant. However in your bullet point list, you wrote "lighting" when you meant I think "lightning", but how as an examiner can I give you credit just because I think you probably meant something else than that which you wrote?

Had there been a little more on related issues (which I think there should have been) such as traction transients, rolling stock compatibility issues, and wider EMI compatibility issues (you just mentioned one specific item of EM radiation in that list but did fortunately refer to inductive effects later), then the examiner would have felt better justified to correct mentally your spelling- if you are just going to use a single word then it must be right!

I'd possibly also have mentioned other "environmental" factors such as accessibility for maintenance and indeed the likely competence level of technicians and the organisation generally. i.e. think of the human side.

Although some of the heritage lines in the UK do use some pretty "cutting edge" stuff, generally they tend to use older more basic technologies. Sure one of the reasons they do this is that they are seeking to preserve history for posterity, sure they also haven't generally got much money for investment and so if can reuse and recycle that has great advantages, but also they do need to consider who as volunteers are going to design, install, test and maintain it. Those people that may well have the skills and experience to do so because of their 'day job", probably don't want to be committed to do much the same in their leisure hours and prefer to do something different! So some slight reference to "appropriate technology" that fits the current organisation and skill base that already exists in a particular railway's environment would have been a good addition.

Hi,
I have had a go at Q10 from last year's paper. I would welcome any comments.

[Jerry1237]

Hello Hort,

Liked the bullet list. Two thing to add would be vandelism and dust/dirt ingress (the other part of IP rating).

Section a), you could mention vandelism again and also UPS/power supplies. Electromagnetic radiation doesn't mean a lot to me. Use of the terms EMC or EMI is more widely understood and would gain extra marks if the student understands the difference between the two!

In section b) you raise an interesting point of how to evacuate heat but keep the IP rating. Don't stricly agree with the first sentence but agree with what you were trying to say. For me, although the points were valid, there was too much on the mitigation of possible site issues.

Train bourne equipment has just about the worst environment to live in. As PJW stated, axle-end tachos are notorious for failure due to mechanical wear, vibrations or being struck!

The conclusion is the attempt was good. It showed some insight but the answer should be limited to what the question is asking and answer it concisely, completely and explicitly. Keep going as I feel you are making great improvements with your technique.

Jerry

[Hort]

thanks for the comments.

I did consider mentioning vandalism and, in particular, the massive problems were are currently having with cable thefts and the innovative ways used to combat it, however, I felt that this was not within the scope of the question. If, during the exam, I came to the end of the questionm with time to spare then I probably would have mentioned it.

[Jerry1237]

Vandelism prone areas require hire security cabinets which often affects factors such as heat extraction, cable entry, maintainability. Have a read of the Rail Engineer this month (issue 83 from memory) about the loc that suffered an arson attack shortly after commissioning. The loc and other equipment has been designed to a high level of securtiy.