Joined: 16/02/2004(UTC) Posts: 15,443 Location: DE-NW
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Are you still painting your rails in rusty brown? Deutsche Bahn are painting some rails white to reduce the heat-up in Summer. Currently this is a local test. And now the hot days have come and they can see if the paint makes a difference. German news article: https://www.t-online.de/...n-das-ist-der-grund.html |
Regards Tom --- "In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS  |
 4 users liked this useful post by H0
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Joined: 04/12/2013(UTC) Posts: 2,261 Location: Hobart, Australia
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Hello Tom, Over the last 5 years or so I have noticed that some of the rails on the railway causeway to Venice seemed to be painted white  and I have posted some images of same on this great Users Group:    This resulted in some discussion on this forum after my post which wondered if this was to counter the effects of heat  : Regards, Philip
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 5 users liked this useful post by PJMärklin
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Joined: 18/02/2008(UTC) Posts: 1,334
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It is more interesting to find a way to transform that heat energy in some useful energy rather than reflect it out. I don't know if there is some practical way of doing it and probably if it was easy and profitable it was already in test or production.
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Best regards, Miguel
Mostly Märklin H0.
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Joined: 10/02/2006(UTC) Posts: 3,997
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its hard to believe that this works.
A black object radiates and absorbs heat faster, so painting the sides of the rail white is going to slow the rate at which heat radiates from it. The sides are not perpendicular to the sun's rays, so I would expect a net increase in temperature by painting the sides white. |
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Joined: 18/02/2008(UTC) Posts: 1,334
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Originally Posted by: DaleSchultz  its hard to believe that this works.
A black object radiates and absorbs heat faster, so painting the sides of the rail white is going to slow the rate at which heat radiates from it. The sides are not perpendicular to the sun's rays, so I would expect a net increase in temperature by painting the sides white. They need to use kind of a Goretex paint. Just it needs to work for sun radiation instead work for breath ;) |
Best regards, Miguel
Mostly Märklin H0.
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Joined: 23/07/2014(UTC) Posts: 8,476 Location: ENGLAND, Didcot
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Originally Posted by: DaleSchultz  its hard to believe that this works.
A black object radiates and absorbs heat faster, so painting the sides of the rail white is going to slow the rate at which heat radiates from it. The sides are not perpendicular to the sun's rays, so I would expect a net increase in temperature by painting the sides white. But surely half the problem is the rails absorbing heat, so the white will slow down the absorption, which will mean they don't reach the same temperature during the day, and hence the rail expansion will be lower.
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 1 user liked this useful post by kiwiAlan
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Joined: 04/08/2018(UTC) Posts: 1,157
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it will certainly help a bit. And it will be a boring, but safe job..........  as a side note, most ship superstructure are white, to reflect as much light/heat as possible
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 1 user liked this useful post by bph
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Joined: 08/11/2005(UTC) Posts: 3,528 Location: Mullerup, 4200 Slagelse
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It works well on wind turbines 25 - 30 years ago, the first wind turbines were grey, because they were galvanized. In Scandinavia, this was not a problem; but when the first turbines were installed in Texas, the grey towers got so hot that it was hard to work inside; even though the heat-producing parts like the generator etc. is above the tower, in the nacelle. Painting them white reduced the average temperature in the towers with more than 10 degrees Celsius. This is what I was told; apparently there are a few reasons more: https://interestingengin...posite%20rotor%20blades. Per. |
If you can dream it, you can do it! I, the copyright holder of this work, hereby release it into the public domain. This applies worldwide. In case this is not legally possible: I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.  |
 1 user liked this useful post by Purellum
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Joined: 04/12/2013(UTC) Posts: 2,261 Location: Hobart, Australia
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Originally Posted by: Purellum  It works well on wind turbines 25 - 30 years ago, the first wind turbines were grey, because they were galvanized. In Scandinavia, this was not a problem; but when the first turbines were installed in Texas, the grey towers got so hot that it was hard to work inside; even though the heat-producing parts like the generator etc. is above the tower, in the nacelle. Painting them white reduced the average temperature in the towers with more than 10 degrees Celsius. This is what I was told; apparently there are a few reasons more: https://interestingengin...posite%20rotor%20blades. Per. Thanks Per for : https://interestingengin...posite%20rotor%20blades. - I really liked the underview of the Spitfire
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Joined: 22/01/2009(UTC) Posts: 14,875 Location: On 1965 Märklin Boulevard just around from Roco Square
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Loco drivers complained about the white rails, you can't see them in winter time when the tracks are covered with snow and therefore you don't know where you going |
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 2 users liked this useful post by river6109
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Joined: 23/07/2014(UTC) Posts: 8,476 Location: ENGLAND, Didcot
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 1 user liked this useful post by kiwiAlan
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Joined: 20/01/2015(UTC) Posts: 1,201 Location: Kerikeri
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Sorry to side track. During WW2, an RAF person was sitting at an airfield when a civilian plane took off. He watched it for a while, looked down, then found it hard to see it again. He made inquiries and found out it was painted a pale green. Thats why WW2 British aircraft most often were painted pale green underneath. Interestingly, the lightened spitfires [ no armaments etc to help them go faster ] used for spying, were painted pink, so they could not be seen coming out of the sun. They used these apparently to track coastal installations deemed dangerous to the allies, and the flew very low over the sea and coast taking pictures. Cant remember where I read about that. With the modern technique of welding rails together, there was now no ability to absorb expansion [ talked about in the films mentioned by ShannonN ] that I could work out. Dereck Couldn't resist when spitfires were mentioned. But I did get back on track.  |
Northland. NZ REMEMBER 0228 for ä |
 2 users liked this useful post by dominator
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Joined: 23/07/2014(UTC) Posts: 8,476 Location: ENGLAND, Didcot
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Originally Posted by: dominator  Interestingly, the lightened spitfires [ no armaments etc to help them go faster ] used for spying, were painted pink, so they could not be seen coming out of the sun.
I understood they were painted sky blue like the picture above in this thread so they were less easily seen against the sky. But the bigger problem they had was they were flying so high they left vapour trails, so apparently part of the job was adjusting your height to minimise these trails as it gave those on the ground clues as to where the plane was and its heading. There may have been others painted pink, but I haven't seen that mentioned anywhere or photos of them.
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Joined: 10/02/2006(UTC) Posts: 3,997
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Originally Posted by: kiwiAlan  But surely half the problem is the rails absorbing heat, so the white will slow down the absorption, which will mean they don't reach the same temperature during the day, and hence the rail expansion will be lower.
yes, but the sides of the rails are vertical, and the solar flux comes from above, so the effectiveness of blocking the sun's rays will be limited by the angle of incidence of the rays. In other words the sides of the rail is not where a lot of the heat gets into the rail. Black sided rails would radiate as much as possible. It makes sense to paint surfaces that face the sun, such as a roof. |
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Joined: 05/06/2004(UTC) Posts: 16 Location: Atlanta, GA
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Thee Austrians are way ahead: -=tom=-
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 3 users liked this useful post by torle
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Joined: 10/02/2006(UTC) Posts: 3,997
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Hello Tom!
long time no hear! Glad to see you are here!
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Joined: 15/09/2014(UTC) Posts: 682 Location: London
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If you can access the "BBC iPlayer", see the program "Inside Central Station", Series 1: Episode 2 at about 54:44 into the episode, you can see Network Rail painting the rails in Scotland.
Carim
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Joined: 23/07/2014(UTC) Posts: 8,476 Location: ENGLAND, Didcot
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Originally Posted by: torle  Thee Austrians are way ahead:
-=tom=- Next years Insider wagon ???
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Joined: 23/04/2019(UTC) Posts: 497 Location: Copenhagen, Denmark
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Originally Posted by: DaleSchultz  Originally Posted by: kiwiAlan  But surely half the problem is the rails absorbing heat, so the white will slow down the absorption, which will mean they don't reach the same temperature during the day, and hence the rail expansion will be lower.
yes, but the sides of the rails are vertical, and the solar flux comes from above, so the effectiveness of blocking the sun's rays will be limited by the angle of incidence of the rays. In other words the sides of the rail is not where a lot of the heat gets into the rail. Black sided rails would radiate as much as possible. It makes sense to paint surfaces that face the sun, such as a roof. The sun is never vertical above the tracks in Germany. Even if it was it would only be for a quite limited time each day. So white on the sides is still less heat.
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Joined: 30/08/2002(UTC) Posts: 1,288
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Interesting (?) facts on suncurves from the Swedish Transport Administration: Welded rails should be laid during neutral conditions, e.g. approx. in the areas average temperature. In these conditions, rails are laid without having any tension. Proper laid welded rails should not move at all. On welded tracks, suncurves generally only occur - when there are bad fastenings to the concrete sleepers or bad ballast OR - if they are laid under non-neutral conditions OR - in areas close to turnouts or non-welded sections. Suncurves still occur every year even on welded tracks, mainly due to lack of funding for maintenance. There are bigger challenges in northern Europe than in southern Europe, due to the wider span in temperatures. MY OWN CONCLUSION: Painting the rails is a temporary solution for managing badly laid or badly maintained tracks. |
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Joined: 10/01/2005(UTC) Posts: 1,024 Location: Den Helder, Noord-Holland
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A difference between the sides and the top of rails that are regularly used is that the top is fairly reflective (being "polished" by the wheels of the passing trains), while the sides tend to go brown … |
Figomima division, UP; mostly figment of my imagination yet. |
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Joined: 23/07/2014(UTC) Posts: 8,476 Location: ENGLAND, Didcot
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Originally Posted by: Copenhagen  The sun is never vertical above the tracks in Germany. Even if it was it would only be for a quite limited time each day. So white on the sides is still less heat.
In the UK you would set a solar panel at about 55 degrees and it will get roughly even illumination at the extremes of sun altitude (i.e. longest and shortest days). I would think that Germany would be at a similar enough angle, so painting the sides of the rails would be worth while.
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