Europe is getting hotter. In the past few weeks, a heatwave crawled across the continent. It broke temperature records in many places. Railways are not immune to the heat. When temperatures grow, so do the tracks. This can cause a phenomenon called track buckling. RailFreight.com takes a look at the implications for the future: is track buckling a big challenge, and what can we do against it?
On 26 June, a deformation in the tracks caused by high temperatures led to a train derailment in the Gothenburg area of Sweden. A particularly unfortunate case of track buckling, considering that this route already functioned as a detour route for a closure on the busy Stockholm-Gothenburg railway.
RailFreight.com approached the Swedish infrastructure manager Trafikverket, as well as the Austrian infrastructure manager ÖBB, to find out more about track buckling (also known as a sun kink in American English).
Despite increasing temperatures, track buckling has become much less of a challenge in recent years. Both Trafikverket and ÖBB confirm this. In the case of Sweden, a 2025 report on track buckling shows a notable decrease. That is interesting, because there is a clear correlation between higher average temperatures in summer and the number of track buckling cases. Yet, that correlation has evidently weakened compared to Trafikverket’s early figures from 2008-2010.
In fact, Trafikverket only identified 30 cases of track buckling in 2023, 2024 and 2025, for a total of 90 cases during these three years. These are record lows, only bested by 2017 and 2012 (19 and 27 cases respectively). In 2008, there were 82 incidents, 64 in 2009 and 51 in 2010 — despite lower average temperatures.
Which measures have we taken against track buckling?
Measures to combat track deformations have proven to be effective, conclude both the Austrian and Swedish infrastructure managers. “This is primarily due to the ongoing modernisation of the rail network and the increased use of concrete ties”, explains ÖBB.
“Track buckling occurs mainly on older lines with wooden ties [sleepers], and is therefore more common on regional rail lines.” On newer railways, the risk of track buckling is significantly lower. Austria only uses concrete sleepers only these lines.
“[…] due to their greater weight and stability, they ensure the track remains level much more effectively, even at high temperatures”, ÖBB adds. “Switching to a heavy track structure with concrete ties [sleepers] is the most effective measure for preventing track buckling.”
Jointed and jointless tracks
The Swedes at Trafikverket have concluded the same as ÖBB. They add another factor, though: it seems that jointless tracks resist track buckling better than jointed tracks. This is another interesting finding: jointed tracks leave small gaps between various sections of rail, which allows the tracks to expand in hot weather. Despite that, continuous (jointless) rails, which leave no space for expansion, fare better against the heat.
“Jointed tracks constituted approximately 16% of the infrastructure mass”, the Trafikverket report says. “Since 24% of the sun curves that occurred in 2025 occurred on jointed tracks, this corresponds to an overrepresentation of approximately a factor of 1.5.”
Since jointless tracks require less maintenance, it sure seems that they are Europe’s best option for the future, despite being more expensive to build. Sweden has replaced 370 kilometres of older, jointed tracks between 2018 and 2024.
The report does not indicate if jointed tracks, which are likely to be older, use wooden sleepers more often than jointless tracks. That does, however, seem likely. All eight cases of track buckling on jointed tracks in Sweden occurred on infrastructure with wooden sleepers. Only six out of 21 cases of track buckling on jointless track occurred at sites with wooden sleepers.
Speed reductions prevent track buckling
The general idea conveyed by ÖBB and Trafikverket is simple: concrete sleepers help prevent track buckling, and jointless tracks seem to do so too on the basis of Swedish data.
If the risk of track buckling persists, however, there is more that one can do. In 2022, Sweden started reducing speeds or cancelling operations altogether on particularly sensitive tracks. No track buckling has occurred on these tracks when those measures were active, suggesting that reducing the exerted force on the tracks helps to prevent track buckling.
Austria has been doing the same during the latest heatwave. “We have preemptively reduced speeds in the Rhine Valley in Vorarlberg, as there has been an increase in track deformation there. This protects both the trains and the infrastructure”, ÖBB explains.