Metro Layout

[PJW]

Hi All,
I am also planning to do the metro layout (Module 2) as i have worked more than 3 years for metro projects. I have worked on Westinghouse DTG-R projects for 2 years and also i have done some scheme simulations (headway calculations, RORI, AIRI etc.) by using tool. I feel doing calculations manually is a bit tough for me.

Now iam bit confused whether shall i follow WRSL DTG-R practise or Thales SelTrac Moving block technology. I don't have much exposure on Thales SelTrac system headway calculations but i am confident on WRSL DTG-R system.

Hope I can help you & vice versa....

Hi peter, i hope you can recognise me as I met you in YM AGM this january. Any suggestions/ideas from you?

Indeed: I think that you also met "Peter" on that occasion.

The truth is that few have done the Metro layout in recent years; it really would be good to see more attempting it. I think it is partly a matter of training availability in the UK that metro people find it easier to learn to do the mainline layout.

Given what you say "I don't have much exposure on Thales SelTrac system headway calculations" I do find myself wondering why you pose the question as it would appear to be a "no-brainer". I understand that the calcs are usually done using a tool- I can tell you that on the mainline that is also the case even though they are a lot simpler.

Although I now work for WRSL, I am afraid I don't know much about DTG at all. I understand that in concept the "state of the railway" is broadcast and the trains have a "system map" on board and work out themselves how far / fast to proceed. I don't think that very many Transmission Based Signalling layouts have been offered by candidates and I have already prompted the examiners that they ought to start thinking how to mark a layout answered utilising ETCS. I think that they'd have little to compare your answer against (I am not saying they don't know what is right / wrong but that they may not have experience of what represents a decent atempt at the exam layout in exam conditions).

So don't worry too much about the detail. Think about how to use your 90minutes to demonstrate to the examiners your experience in applying DTG. Look at the percentage of the marks available for the different portions of the question and work out what allowance that gives you in terms of time you can expend. In particular then consider what you can do to demonstrate an UNDERSTANDING of braking and headway and how these constrain the signalling solution.

Perhaps you could explain to us what RORI, AIRI mean (do spell out the abbrieviations in the exam- I think that the first means "Run In / Run Out time" which is a measure of dwell time but I can't guess the other).
I suspect that braking is a responsibility of the trains- I do not know whether this affects scheme design directly or just needs to be taken into account when working out the headway which can be achieved.
What tyou need to do is distill that which is the ESSENCE of the calculations and state as bullet points all the assumptions / simplifications that you are having to make because you are doing the calculations long-hand in limited time.

I think that provided your answer demonstrates a high-level understanding with a good explanation that the examiners will be so pleased to get a Metro layout for once that if it looks half decent then you'd get a good mark.

This is a general message but probably particularly relevant to you and your problem; DON'T GET BOGGED DOWN IN DETAIL BUT ADDRESS THE WHOLE QUESTION, DEMONSTRATE YOUR GENERAL EXPERIENCE, AVOID THINGS THAT ARE OBVIOUSLY STUPID- you'll be alright.