(06-08-2010, 07:14 AM)PJW Wrote: (06-08-2010, 12:09 AM)hiteshp Wrote: Our study group In Brisbane looked at the 2008 paper Questions 1 - 4 last Tuesday and would appreciate some feedback.
We would also like to ask whether the answer reflects the time available to answer three questions.
Thanks,
Hitesh, Laura & Johnson.
Q4. I suspect you were running out of time by now and thus this is quite sketchy.
I think this is the only answer in which there was a hint of the railway context in which you are answering. It is generally worth including such a statement in the beginning of your answer; I think this is particularly important for those whose practices are different from UK.
Further more detailed feedback to follow
I don't think this is a question that I would have chosen in the exam and certainly it was by far the weakest of your answers. Only half a page, didn't even seem to attempt the middle section (40% of the marks), think you misunderstood the last bit and the initial portion was itself fairly weak.
However well done for deciding to give it a go; I like your style of sitting down as a group to do questions 1-4 of a paper rather than just picking off a favourite type of question
Nevertheless you ought to be able to do rather better at this one and so I suggest that you discuss again and try to get a better answer together- it is by doing that you will learn.
A few hints to think upon:
1. Initial version of location design given to factory for pre-wiring REB; not built exactly as per design because of the size of some equipment wasn't as the designer assumed. How is this change managed?
2. By the time it is shipped to site more detail is available on site cable routes and some initial assumptions are now known not to be true. One of the discoveries is that the A and B datalinks as designed can no longer be routed via diverse routes as they both cross into and out of the REB via the same UTX and another route is not practicable. Hence significant changes in the area are needed to where data link spurs commence / terminate and the order in which the locations in the station area are connected; the locations have mainly been designed, some are currently in manufacture, some are in the site compound, others are placed in position ready to be cabled. To make use of the necessary possession the datalink cables have to be run to a "back of a fag packet" design cobbled together on site at the eleventh hour to suit the actual cable routes avaailable and hence the ends don't match the locations as built which therefore need to be modified. Those locations shipped to site have had Test Copies issued, those yet to be shipped to site have not. How are these changes managed?
3. Also the client has now changed its mind and now requires that the new signalling system interfaces with two existing conventional signals located in a slightly but significantly different position to the oriinally intended new LED signals. Instead of being clear of junctions their overlaps now extend over them and additional track circuits are required so that there are joints at the signal positions. The locs have been built, the interlocking data and control system screen layouts etc. were all designed before this changes was advised, but since the interlocking data was being tested it was possible to incorporate the change into a re-work cycle clearing test logs from the first pass, so it now is incompatible with the location design. The control centre design is being undertaken by another contractor who is waiting for the commercial implication of this change to be contractually agreed before reworking their data. Given that it will soon be necessary to undertake through testing (site integration testing) how is this going to be achieved?
4. Later it becomes clear that certain items of equipment aren't going to be available in the necesary timescales and an alternative solution using differnt equipment is needed. How are these changes managed?
5. Tester writes Test Log to draw attention that there is a client requirement to provide Earth leakage Detection if more than one point number fed from one busbar and that the design is non-compliant. Problem is that no suitable equipment with product approval is available that is compatible with SSI point modules; necessitates reallocation of certin point ends to different TFMs. The data has been tested, the locations function tested locally and are about to be through tested to the interlockking and control system. How is this change managed?
6. Project includes element of novelty in that the computer based interlocking has never interfaced with the particular signallers control system before. During integration testing certain changes to the product software are required; however this emerges after the hardware has been shipped to site and much of the data testing has been undertaken off-site. How is this change managed?
7. An expected derogation to permit the perpetuation of an existing infrastructure deficiency is not achieved and therefore this now needs to be addressed and extends the scope of the project needing changes outside the originally expected area of change. How is this change managed?
8. When undertaking preparatory work at a location, it is discovered that the site maintenance records on site are of a later version than those officially supplied to the project by the National Records Group and have been used for the design. How is this change managed?
9. Chance discussion with a signaller reveals that they have a different understanding of which routes are currently available for use on the existing layout than is officially known to the signalling records. How is this change managed?
10. A series of enabling stagework is being taken every weekend; approved design is programmed to be issued at T-6 weeks and has to be designed on the assumption that the work in the interim period is undertaken as planned. One possession's work is completely lost due to emergency engineering work taking priority, another weekend's work has to be partially de-scoped due to a key member of staff failing to turn up for the shift, another can't be done because of the outstanding modification necessitated by item 4- so what does that do to the design and maintenance records for the later weekend?
11. A design of an electronic cubicle was approved by the client before being committed to manufacture and has been partially brought into use for those areas commissioned as the first stages of the project. When submitted purely to show the remainder brought into use at the final commissioning, a different reviewer rejects the design on behalf of the client and now requires an alteration which affects the whole cubicle. How is this change managed?
12. The client decides that they can save money long term by making use of a new node on their own fibre optic network rather than provide the originally anticipated connection via a public telecomms supplier; however this is located 2km further away than the original site necessitating the extension of the trackside datalinks and therefore a reassessment of the placement of the positions of the intermediate isolating transformers. How are these changes managed?
13. On a rehearsal weekend it is discovered that a decision to use 961 relays rather than perpetuate the use of old non-standard non-safety relays used for indications failed to take account of ohns law and when connected to the line circuit, the voltage falls from 50V to 30V and they do not pick. Contacts of the new relays have been used and have been pre-tested to the remote signalling centre. How is the necessary change managed?
14. A Technical Query asking the client to clarify and resolve discrepencies between the Control Tables (supplied as warranted documents to which the site data has been written) and the Interlocking Requirements Specfication (supplied against which the Principles testers are assessing the achieved functionality) is answered in a way that sometimes requires the data to be comply with the CTs but different from the IRS, sometimes in accordance with the IRS and therefore requirong an amendment to the CTs. How are the necessary change managed?
15. The Signal Control Centre is being provided by another supplier and they were initially responsible for defining the allocation of the bits within the TDM remote control system to all the existing RRI relay rooms whose control is to be transferred to that centre. During the signalling design of one such remote relay room's TDM interface, it is discovered that certain functions are not actually available in that room but are actually present at the next relay room along the line and therefore should be provided in that TDM system instead. The signalling design for that site has already been issued and unfortunately to make matters worse there are no spare bits on the existing input cards. Hence it necessitates the provision of a new DIP card within that field end cubicle- this is depicted in a separate set of diagrams and has already been delivered to site in accordance them and having been issued with a Certificate of Conformity after FAT testing. The control centre contractor's end of the remote control system will not initiate communication with the field end when there is a mis-match between the cards installed on site and the ones it expects, yet a rehearsal of the system must be undertaken in an imminent scheduled possession. How are the necessary changes managed?
16. A part of the area relevant to a particular control system has already been commissioned whilst the remainder of the area is to be transferred to it later. However it was not possible to perform the necessary pre-testing for the entire final area before the first commissioning was scheduled. Therefore "stage data" has to be installed in the real DIS cubicle 1 to operate the real railway. Meanwhile the "final" version of the same cubicle's data must be installed in the actual DIS2 cubicle reconfigured temporarily to be made to think it is DIS1 but obviously disconnected from the actual signalling ring connected to a temporary test ring instead. Similarly an extra temporary DIS cubicle mus be brought to site and also connected to that test ring,configured as if it were DIS2 with its "final" data.
Then after all the testing is complete at the final stage commissioning the real DIS1 will be loaded with its final data and the real DIS2 stop pretending to be another DIS1 but become itself again connected back onto the final connnections and loaded with its final data and the test ring and the extra DIS cubicle can be disconnected and removed from site. Simples!
I could go on and on but perhaps that gives you sufficient food for thought to construct a more complete answer.
[I'd be
extremely interested to discover what you think the right answer is although it should be stated that any similarity between the above list of items and any project that I may currently be working on is obviously entirely coincidental, of course!]