Zürcher Nachrichten - Paint them white: how Brazil is keeping trains on track

Yet just last week, a train in the Brazilian state of Rio de Janeiro derailed after the tracks expanded and buckled after being heated to a sizzling 71 degrees Celsius (160 degrees Fahrenheit) by the sun.

No-one was injured in the incident but it highlighted the need for a solution to the search for a way to keep the country's tracks cool in increasingly sweltering temperatures.

A railway company in Sao Paulo, Brazil's most populous city, claims to have found a solution: give the tracks a lick of white paint to reflect the sun's rays and prevent the steel from overheating.

"We have recorded temperatures of up to 60°C on the tracks, which can lead to deformations and be dangerous for trains," Alan Santana de Paula, maintenance manager for ViaMobilidade, a company that operates two commuter train lines in Sao Paulo, told AFP.

ViaMobilidade transport 800,000 passengers a day.

Last year, it counted 20 deformations on the tracks during periods of intense heat.

Brazil, like the planet as a whole, experienced its hottest year on record in 2024, a situation scientists have linked to climate change.

The experiment of painting rails in light colors has already been carried out elsewhere in the world, and opinions are divided on its effectiveness.

Tests carried out by ViaMobilidade showed that white paint can help lower the temperature of the tracks by six degrees Celsius because white absorbs much less heat than dark colors.

"It doesn't completely eliminate the effect (of the heat) but it does diminish it," said Santana de Paula, who is heading a project to paint 35 kilometers (22 miles) of tracks by the end of February.

To achieve its aim ViaMobilidade has come up with a novel device: a pick-up truck is fitted with sprayers at the back and drives the length of the track, dousing it with a water-based paint.

Sao Paulo, like other parts of Brazil, suffered scorching temperatures earlier this month, with temperatures in Rio rising above 40 degrees Celsius for several days in a row -- the highest in the city in over a decade.

While Latin America's largest country has few long-distance rail links, people in big cities often use trains to move about.

Santana said train traffic was being impacted by all kinds of severe weather, from heatwaves to torrential rain and gusting winds.

Sao Paulo was in the past few weeks lashed by heavy storms which caused widespread flooding and power outages.

D.Graf--NZN