Brazil Paints Train Rails White

Brazil’s ViaMobilidade has begun painting the train rails of several of the lines it operates to attempt to limit the amount of steel rail “flambagem,” or buckling. 

Some sections of track in the Sao Paulo area, where the paint protection is being tested, look like spaghetti after overheating. In 2024, about 20 buckling deformations of track rail were identified by the company.

Earlier this year, the company painted the sides of 35 kilometers (about 22 miles) of rails on Line 8 and Line 9 in Sao Paulo state to limit solar overheating. When buckling occurs, trains must slow speed to
avoid derailing. 

In extreme temperature cases, welded rail ends move apart completely. In Sao Paulo, the rails can reach as much as 70°C, or about 160°F.

“We used a water-based white enamel, without special additives,” noted Alan Santana, the executive director of maintenance for ViaMobilidade, in a recent email to CW. 

Santana expects the paint to reduce the heating of the rails by 10% or about 6°C.

To paint the rails, the company’s maintenance technicians mounted a rail pickup truck carrying a paint spray rig with stationary arms extending down to the rail level where nozzles sprayed the sides, the middle web, and parts of the bottom foot, along with pad mounting hardware.

ViaMobilidade parent company Grupo CCR operates 36 transportation concessions across Brazil, including airports, toll roads, and train systems.

Rail Painting In Other Countries

Rail companies in different countries have been testing the application of heat-deflecting coatings on rails to prevent buckling.

Among recent rail painting projects, London-based Network Rail announced plans in April of this year to use some 1,500 liters of paint — amounting to a covered area of some 30,000 square meters. 

“We spray the rail with standard white emulsion,” said Charlie Oven, a spokesman for Network Rail, in an email.

“Extremely hot weather is a serious challenge for the railway. Last year, hot weather caused rails to buckle, leading to 350,006 minutes (240 days) of delays,” Network rail stated on its website. 

The company used “hundreds” of painters with brushes and rollers to apply a white paint to the rails.

“Our railway has 20,000 miles of track and in a summer heatwave, rails in direct sunshine can be as much as 20°C (about 68°F) hotter than air temperature,” said Lisa Angus, industry weather response director at Network Rail, in the statement. “Typically, a rail painted white is 5°C to 10°C cooler than one left unpainted.” 

Italy has been engaged in painting rails white for many years. Trenitalia, Italy’s main railway operator, uses white coatings on its rails. 

Trenitalia operates high-speed train services like Frecciarossa and Frecciabianca, connecting major Italian cities.

In Switzerland, the Rhaetian Railway External link in the eastern Swiss canton of Graubünden painted tracks white in a 2018 test. Austrian rail company ÖBB performed a test in 2019.

Indian Railways applies white coatings to the top of passenger rail cars to reduce the roof temperature. Passengers on Indian trains often ride on the tops of cars. The rail system operates Linke-Hofmann-Busch passenger coaches.

In Asia, Vietnam also has tested white rail coatings, and researchers there have embraced the need for ceramic particle additives for best heat control performance. 

Regional Demand for Heat Blocking Coatings

The potential demand for white rail coatings in South America is large. South America has approximately 83,558 miles (134,474 kilometers) of railroads, according to the World Population Review. Argentina and Brazil have the largest railway networks on the continent, the Review notes.

That rail network is expanding. A joint Chinese/Brazilian project at the study phase calls for a $70 billion, 2,800-mile rail link between the Brazilian port of Santos and the Peruvian port of Chancay. This line would cross the Andes mountains.

The Types of Heat-Blocking Coatings

Formulations for so-called cool coatings — typically used on commercial building roofs — include acrylics, often preferred for their ease of use and quick drying time, while enamels are a popular choice for their durability, suggests Google AI.

More advanced Thermal Barrier Coatings (TBCs) are advanced materials that often are ceramic-based, with several potential additives utilized for different heat control functions. 

One U.S. manufacturer of TBCs is SPI Coatings, based in Shawnee, Kansas, which produces Super Therm for blocking thermal loading. The coating was tested in Oklahoma on KCS/Watco rail systems years ago because a train operator was forced to reduce train speed to about 10 miles per hour through certain overheated areas, in contrast to normal operating speeds of 40 MPH or more, said Joseph Pritchett, president of SPI, in a recent interview with CW. 

The Oklahoma test involved application of Super Therm at 450 microns wet and 250 microns dry. “It worked, permitting normal speed operations,” Pritchett said.

The U.S. Department of Energy’s Oak Ridge National Laboratory tested Super Therm on a rooftop years ago, in which the temperature of the roof without coating was 164°F during an ambient temperature of 85°F. 

Once the roof received the “Radiation Control Coating,” the roof registered a temperature of 86°F, or 1° over ambient.

To contrast the functionality of the Super Therm TBC, the Oak Ridge test coated a section of the roof with elastomeric reflective paint, which yielded a roof temperature of 125°F. Apart from the reduction of roof temperature, the lab found the interior ambient temperature was reduced 10.2°F. The test was titled Weatherization Testing Report.

Beyond North America, Super Therm has been tested in Australia, India, Japan (with Keihin Electric Railway) and Sri Lanka, Pritchett notes. 

The coating has been tested and used not only on rails, rail facilities and equipment, but also on bridges, and on maritime vessels, he said. In Japan alone, more than 10 million square meters of the company’s coatings have been applied, including commercial and industrial rooftops, SPI states.

In India’s rail car test, “Super Therm stopped transfer of heat through the roof of the coaches by blocking 99.5% of the infrared ‘long wave’ from the sun. 

This resulted in blocking the heat load from the sun while preventing expansion and contraction of the roof surface caused by heat from radiation and altogether prevents corrosion due to condensation,” Pritchett explains.

Multiple Ceramics In One Formulation

The Super Therm formulation was developed through cooperation with NASA’s Marshall Space Center, Pritchett says. 

“After six years (1989-1995) of testing of more than 700 different kinds of ceramic components, four ceramics were chosen with the greatest ability of radiational ‘heat’ reflection and the smallest heat conductivity were ultimately selected,” he said. The final coating of a wet formulation is typically 450 microns, based on ceramic particles 4 microns in diameter, the company spec
sheet indicates. 

“Everyone needs to understand that tests showing only reflectivity of light is not reflectivity of ‘heat’,” Pritchett said. “This point is missed on testing results. That is why SPI Coatings tests for heat reduction and not how bright white a coating can be in reflecting light only which is not
altogether heat.”

The coating blocks heat across three distinct wave lengths to ‘neutralize heat’, including UV, shortwave or visible light, and long wave or infrared,” he said. UV light contains 3% of the total energy from light, visible light contains 40%, and infrared contains 57% of light energy, felt as heat, SPI states.

Another critical point in this testing is that Super Therm was tested at 25°C, 50°C, 75°C and 100°C. 

The most important part of this testing was that the “heat blocking” ability of Super Therm results on all four temperature levels was that there was no more than a 5% difference in heat blocking ability. Pritchett noted that all standard insulation materials are only tested at 23.9°C (75°F) for insulation ability.

The Super Therm formula – also a thin film insulation – with 10 mils or 250 micron dry thickness facing the sun heat radiation includes four cross-linked acrylic binding bases to afford toughness, durability, adhesion and water resistance in the field, Pritchett explained. The coating is loaded with four unique ceramic compounds to match the heat wave size and crystalline structure to block heat absorption
Vand transfer. 

Another variation of the category of Insulation coatings is what is referred to as “Thick Film Insulation Coating” formulas, which include silicon/acrylic hybrids for flexibility, he addsed The Thick Film is applied during operations without shutdown to hot surfaces up to 1200°F/650°C to hold the heat on the exterior surface of the unit to prevent the loss of this heat escaping to the exterior climate. 

If the surface heat is blocked from escaping, this holds the heat inside the unit (pipe, heat exchanger, tanks and any hot vessel), dramatically increasing the efficiency of operation of the unit in field calculations up to 80% savings in loss energy. 

This was verified by Georgia Pacific (Koch Industries) when their engineers removed all the wrap and jacketing from a digester tank which had many years of insulation performance data and replaced with applying HPC thick film insulation coating at approximately 350 mils/9mm dry. 

They recorded a full one year study on performance to find the HPC saved 49% or $332,000 on this one tank in one year. All these coatings are water-based and meet all the safety requirements.