As a result of the extreme heat that Europe has been experiencing this summer, the German rail service has been experimenting with painting their rails white.
Apparently, the white paint helps to reflect the light and heat and can reduce the rail temperature by 7-8 degrees, which helps to eliminate expansion.
Deutsche Bahn Tests White Rails to Reduce Overheating | Railway-News
Who knew Lionel's white Fastrack would be prototypical ?
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My wife and I were talking about that this morning, and then we wondered why railroads in the hot parts of the US don't have those kinds of problems with track damage from extreme heat. After all, there are railroad lines across deserts in the US, and I've never heard of US railroads having to try things like painting rails white.
@West Side Joe posted:My wife and I were talking about that this morning, and then we wondered why railroads in the hot parts of the US don't have those kinds of problems with track damage from extreme heat. After all, there are railroad lines across deserts in the US, and I've never heard of US railroads having to try things like painting rails white.
Very good question. However, let's remember that it virtually NEVER gets THAT hot in Great Britton nor Europe, i.e. over 100 degrees F. Also, the U.S. Desert Southwest can regularly see temperatures well above 100 degrees F in the daytime, then drop to around 60 degrees F at night. The U.S railroads have long since learned how to properly engineer their track structure & roadbed in order to live through such extremes.
Now, as to "painting the rails white", I really don't see how much difference that would make, when the ambient temperature exceeds 100 degrees F.
Every piece of rail in use, that I have ever seen, has been unfinished and non-rusted steel. Would white paint hold up on the portion of the rail that the wheels ride on? If not, what would the point of painting the sides of the rails be, as the sun would still heat up the rails?
@Nation Wide Lines posted:Every piece of rail in use, that I have ever seen, has been unfinished and non-rusted steel. Would white paint hold up on the portion of the rail that the wheels ride on?
Absolutely NOT!
If not, what would the point of painting the sides of the rails be, as the sun would still heat up the rails?
And there you have it!!!!!
What reflects heat better...
1. shiny steel
2. shiny steel, that was once painted with white paint?
Looks like the Germans, famous for their engineering prowess, dropped the ball this time, Nein?
All good points.
I suspect that the durability and wear of the paint will be high on their list of seeing whether the experiment works or not. Perhaps they've developed a new paint formula better able to withstand the forces applied to the rails during service. I don't think we're talking Krylon here. 
I suppose it's also possible that, even if it only lasts a few months during the summer and has to be re-painted at the beginning of each season, it may be worth it if it provides the desired safety results.
Well, I must stand corrected. After doing some Internet digging, US railroads do indeed monitor track temps and issue slow orders to prevent accidents due to "sun kinks" or worse. CSX, Union Pacific, Amtrak and Metrolink in California are among them. I suppose that in Europe, where train service is more intense and higher in speed than here, the potential for major disruptions due to extreme heat is greater. Slow orders may not be a feasible solution in high traffic high speed rail corridors over there.
Unfortunately, there have been many derailments in the US caused by rail sun kinks. An Amtrak train was derailed a few years ago by a sun kink. I don't remember the date. NH Joe
Interesting subject. After some further reading:
Titanium Dioxide has a higher reflectivity index than bare shiny steel according to several seemingly reliable internet sources. Titanium dioxide, a white powdery compound is the active ingredient in many high SPF sunscreen products as well as a pigment used in some white paints.
https://pubchem.ncbi.nlm.nih.g...ion=Refractive-Index
Shiny bare steel does absorb a small percentage of incoming solar radiation.
@Arthur P. Bloom posted:What reflects heat better...
1. shiny steel
2. shiny steel, that was once painted with white paint?
Looks like the Germans, famous for their engineering prowess, dropped the ball this time, Nein?
Arthur,
Did you not look at the OP's link and see that only the sides of the rail were painted white?
FYI. I ride the MARC train in Maryland and most days in the summer there are heat restrictions (slow orders) imposed by CSX. So they do monitor the temperature changes (especially large temperature differences from night to day and between days.). Imposing heat orders seems to be more prevalent on passenger trains than the freight trains , as there are times freight trains continue to fly by while the passenger trains crawl. Probably due to liability.
So, painting an item white to reduce heat absorption, reduce radiated heat, etc., etc., is hardly new science. Painting roofs white, cars white, roads white...all have been shown to have some positive attributes re heat absorption/reflection. But ho-hum white paint is not wholly the answer. Walmart Graffiti Paint is not what we're probably talking about.
Search on white paint applications for cooling and you'll find a lot of new materials science involvement. Here's one brief summary article...
Besides, I'm not usually one to pre-judge German innovation. OTOH, selecting a painted rail comparative test site on a railroad bridge 61meters (200 feet!) above a valley does raise some questions (
) in this hoi polloi's mind.
Cynicism aside, "follow the science", ...if we have to...I suppose...maybe?
The answer is that Europe simply is not used to these kinds of temperatures. 104 degrees in the southwest is common, it just isn't common there so they likely haven't accounted for that. It will be interesting (well, not in a good way) what will happen with the rail network in the Southwest if as they are expecting, they get even higher sustained temperatures. So why would they pain the rails white? Because it is something they can do relatively quickly and cheaply. The sides of rails (which they paint) are generally rusty, and being a darker color will retain more heat.
If as expected these kind of heat waves become more common, the railroads might need to look at different kinds of steel for the rails that perhaps has less of a coefficient of expansion than current steel, or build the track bed where it can better handle expansion and flexing. You can't do that overnight, hence things like painting the rails.
Every few years when I go to Florida on vacation from the Northeast, I see what appears to me to be an overabundance of white cars on the road.
I suspect that's not coincidence. 
104 today in Britain. Average for July is 70s.
Guys...lets not turn this thread into a weather report. Keep on topic and please refrain from posting today's temperatures across the world.
I apologize. I considered that important and on topic but maybe it isn’t. The average temperature for Northern Europe was not brought up. Since Northern Europe is on the same latitudes as Canada, they did not plan for this temperature increase (30 degrees). The white paint is probably a stop gap measure and they need to start talking to the engineers employed by our southwest roads since this will continue.
BTW, car radiators used to always be painted black to enhance the heat transfer. High end computer heat sinks will have an etched, bumpy surface (for more surface area per sq inch), that is oxidized black. The color makes a noticeable difference in heat transfer.
I guess one train derailment would pay for a lot of paint. Mike, are you there?
@aussteve posted:BTW, car radiators used to always be painted black to enhance the heat transfer. High end computer heat sinks will have an etched, bumpy surface (for more surface area per sq inch), that is oxidized black. The color makes a noticeable difference in heat transfer.
I guess one train derailment would pay for a lot of paint. Mike, are you there?
Those items are not in full sun, both are covered, the heat sink in the case and the radiator under the hood. In full sunlight black causes the absorption of energy as heat.
The UK is having the same problem, they had to shut down the tubes and also train lines shut down because of buckling and fires.
Which raises another question, with the high temp in day then cooling off at night, will that cause metal fatigue or cracking of the steel?
Well, it appears that improving ESG scores may have as much (and, probably more) to do with it than physics.
@Dennis-LaRock posted:Well, it appears that improving ESG scores may have as much (and, probably more) to do with it than physics.
I don't know where you got that from the article. It basically said that painting the rails white led to a reduction by 7 degrees K (you can tell geeks wrote this, normal people would use degrees C). It mentioned other things German rail was doing with cooling and insulation not using current foam and such, or buying wind power, but that had nothing to do with trying to keep the tracks from having problems that I can tell.
@bigkid posted:Those items are not in full sun, both are covered, the heat sink in the case and the radiator under the hood. In full sunlight black causes the absorption of energy as heat.
Black colored items absorb heat better than white colors. Conversely they transfer or give up heat better than white. That's why they are black.
@aussteve posted:Black colored items absorb heat better than white colors. Conversely they transfer or give up heat better than white. That's why they are black.
YES ! One of the motorcycle manufacturers wayback in the 60s did a study how the color of the finish on cylinders and heads affected operating temp. They found that since the source of the heat was from inside the engine that a black finish on the cooling fins cooled the engine better than any other color or bare metal fins. As for polished bare metal. As the finish approaches a mirror finish it reflects more and more visible light and less IR. If you can find a shiny clean chrome bumper in the bright sun try and hold your hand on it. It will be about the same temp as a black auto body exposed to the same sun. Perhaps a bit hotter. Look up Project HAARP. Understand that China and Russia have picked up where we left off and put this tech on ships at sea.
I am still planning to paint the sides of the rails of my Ross Sectional track some shade of brown.
The track will be ballasted with coarse gray blend from Woodland Scenics.
Hopefully my Trains & O Scale passengers will be safe.
My basement never gets above 70F.
Hope to avoid white sided rails !!!
CBQ Bill, I think your track will be okay with brown paint. And if your passengers are glued securely in their positions, they should survive as well. I would love to have a basement to retreat to. We are hitting 107 everyday here. So I am going to stick with the shiny silver rails of the Lionel tubular track I have until I can finish the move up north. Then I might join you and paint the sides of my toy train tracks. But then I might have to worry about frost heaves.
This may not be as wacky as it seems. In Arizona they are putting a whiteish-gray sealer on blacktop roads to try and cool them down as one of many things to try in handling heat. I haven't read anything about railroads in Texas or the southwest and the current heat bubble, if they are seeing problems.
@bigkid posted:This may not be as wacky as it seems. In Arizona they are putting a whiteish-gray sealer on blacktop roads to try and cool them down as one of many things to try in handling heat. I haven't read anything about railroads in Texas or the southwest and the current heat bubble, if they are seeing problems.
Which leads me to wonder what if all roads were concrete ? Remember as a kid running around barefooted in the summer. It was killer painful to walk across an asphalt road yet walking on a concrete sidewalk usually wasn't even uncomfortable. Two factors give the concrete an advantage one it reflects much more light than blacktop second it is an evaporative surface where moisture in the soil is constantly wicking through the concrete evaporating and cooling it. Not so with blacktop. When it rains the concrete gets wet below it's top surface which increases and prolongs evaporative cooling. On asphalt the evaporation happens so fast that the prime feature is the sudden rise in humidity and heat when the suns comes out. As for cost and driving comfort asphalt wins no expansion seams to drive across, less glare and much cheaper to build and maintain. Do note that in a arid hot place like the southwest US concrete looses some of it's evaporative advantage however it is still more reflective. As for painting the rails white I cannot see how it can hurt. However two years ago a friend had a new metal roof installed and the company offered him roofing with a clear coating which reflected infrared light they had samples outside in direct sunlight of the same color roofing with and without the coating on black samples side by side you could easily hold your hand on the treated sheet where more than a second or two was all you could manage on the untreated sample. All colors of the treated roofing were cooler even in the shade. Perhaps that tech could be adapted to roads and railroads and roofs and........................ j
@JohnActon posted:Which leads me to wonder what if all roads were concrete ?
I recall the concrete expressways in Chicago occasionally buckling from the heat.
Images on Google can be found of concrete buckling, like this one.
Rusty
@Rusty Traque posted:I recall the concrete expressways in Chicago occasionally buckling from the heat.
Images on Google can be found of concrete buckling, like this one.
Rusty
Your link. That is not a road perhaps a driveway. It certainly would not meet code here in Alabama even for a driveway. If you look at nearly every bridge in the US they are concrete and you don't see them buckling from heat. Yes there are rare incidents of failure bad engineering is not exclusive to Chicago. Which is also one of the cities with broadest winter to summer temps swings and all that implies. Since water can penetrate concrete if you have rainy days followed by a hard prolonged freeze you can have surface damage as deep as an inch If you patch that road in late fall through early spring with concrete you are just begging for it to buckle come August. Most often the cause of the sort of buckling seen in your link is lack of adequate expansion joints. Might Las Vegas be hot enough for you ? The Las Vegas airport has four Runways three were concrete the oldest was asphalt and needed replacing they chose concrete for the replacement. Many runways and roads with asphalt surfaces have concrete underneath. It is especially useful where broad temperature swings occur and allows easy surface repairs to damage caused by winter freezing. This is getting a bit off of buckling railroad track but the same forces are at work. Something I wonder about is what kind of provisions do railroads make for expansion. Are there rail-joiners which have some slip built in to accommodate expansion and contraction ? Any railroad construction engineers on the forum ? j
I have a little background with concrete, my family was in the construction business, and concrete is subject to issues as well. Yes, concrete expands and contracts, it is why when they pour concrete it has expansion joints. If my memory serves me right, concrete doesn't like tension, it likes compression. When concrete expands it is putting it under tension. Rebar used in concrete is there to help handle tension (again if my memory serves me correctly; my dad is looking at me somewhere and shaking his head, saying "didn't I teach you anything?" *lol*) and high temp expansion/contraction could still cause even rebar reinforced concrete to crack.
Where concrete runs into problems I think is if the expansion gaps aren't big enough for the temperatures they have to handle. Concrete has a different coefficient of expansion than asphalt does, or steel, so it expands or contracts less due to temperature changes. Obviously its color helps, gray/light color like concrete will not absorb as much heat as asphault would. The problem is if you are in a place like Maine, the required expansion joint would be smaller than let's say Las Vegas. One of the things a place like Las Vegas has to deal with is extreme swings day and night; in a climate like Las Vegas it can go from 104 in day and drop 50,60 degrees at night, that has to be factored in, too. When you mix concrete the mix changes depending on what you are doing with it, the conditions, and I am pretty sure that the mix they use in a hot climate will be different than a moderate one. The problem with expansion joints is think about the concrete highways and the road noise they generate at speed, it is one of the reasons they switched to asphault (that, and it is easier to lay asphault than pour concrete IME), if you need large joints, going to be noisy.
Back to the original problem, there are ways to address heat with things like railroads. You could have larger rail gaps, but that has its own issues if you need to make them large. Dimly I think I read that using welded rail helped, because the rail expands or contracts over a large distance, that as long as the way the rail was connected to the ties allowed movement, the expansion was over a larger distance (and don't take this as gospel, some of the train guys on here might well know better). I thought that besides durability, concrete rail ties allowed for such ability, but again, hopefully the experts will chime in. Using different steel would also help, different alloys would have different coefficients of expansion, and could help make the problem of buckling less.
Most railroads try to lay new rail when it's hot out, so when it's cool weather, the rail is under tension.
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