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posted: 30 Sep 2020 16:51 from: DerekStuart
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Hello all Following on from Martin's excellent 'live video' tutorial, I revisited importing maps, just to see if this would solve my problem, which it didn't. I wonder how accurate OS maps really are. I know from photos what the geometry of all the main components of a tandem/ crossover are, but these just will not fit into the space on the OS map, which shows just 6ft between the lines. The OS maps also variably show either a type 2 tandem or series of turnouts or omit them altogether. Noting Martin's comments from the video, in this case I know the switch markers are not accurate. Photos suggest that the spacing is greater than 6ft and I wonder if the cartographer assigned to this area got bored or just assumed this would be 6ft as per the rest. There are already discrepancies in the OS maps between early and late 1920s. Would any kind soul have a look at this photo please and give an opinion on the spacing between the left running line as it passes the first turnout of the tandem? I'm guessing about 8 feet. I don't have the photograph owner's permission so can only post a link. http://railway-photography.smugmug.com/Railtours-Year-by-Year/19651970/1965/Whitby-Moors-rail-tour-6th-March-1965/i-fHDF6rX/A Opinions would be welcome, thanks. Derek |
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posted: 30 Sep 2020 17:55 from: DerekStuart
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As is always typical... When you ask someone "how do I//where is//I don't understand" that's always when fate decides to give you the answer. If I use the platform edge marker for the nearside rail- so some 9 inches from the rail- it fits. I tiny difference at A makes a big difference at C. Time to take up stamp collecting... |
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posted: 30 Sep 2020 18:24 from: Martin Wynne
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Hi Derek, Using a pixel ruler on the photo, and dabbing the calculator, I make the tracks at 8ft way, 13ft-2in centres. Plus or minus maybe 3" either way. It is obviously more than 6ft way because of the presence of the ground disc signal. That has a rule 55 diamond on it, and I think I can just see the track circuit wire link by the fishplate. So clearly the picture is more likely 1950s/60s than the 1920 of the map, and the file name suggests 1965. Bearing in mind that the map could have been surveyed 20 years earlier, there could be 60 years between the map and the photo, so it is not surprising if it doesn't match. p.s. thanks for the pic of a tandem. cheers, Martin. |
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posted: 30 Sep 2020 20:40 from: DerekStuart
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Thanks Martin. I used the same method of measuring the screen, but with telephoto effect and whatnot I was doubting myself. This picture was either the 1963 or 64 Whitby Moors rail tour. Around the turn of last Century, the station was modified to include two new bay platforms. I wonder if this resulted in the East platform being eased out a bit (the curve from blocks to throat is not and never has been consistent) and when it was surveyed later with the tandem, the spacing looked the same so was overlooked, save for a quick squiggle to show the revised track plan. This is the same map set that you helped me with the other day and there was a discrepancy between the one I was using and the one you were using- both OS but published 7 years apart. I suspect the same thing happened there- something superficially looked the same so didn't get picked up as a change. I have now found a wide angle photo that confirms your prediction. I will post that in the appropriate thread so anyone reading it will be able to see it. Many thanks again. Derek |
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