High temperatures this summer have caused railway tracks to warp more often than in the past, leading to an increase in service delays in some parts of Japan, with operators taking extra safety precautions due to the heat.

On Aug. 1, it was found that rails had warped on a portion of the Kagoshima Line in Kumamoto Prefecture, leading to the suspension of operations between Uto and Yatsushiro stations while an investigation was conducted, NHK reported. Workers used large blocks of ice to cool the rails and restore the tracks.

Kyushu Railway said in a news release last week that delays are possible, as it might have to reduce train speeds or suspend operations in order to ensure safety.

Hiroaki Fujii, a spokesperson for the company, confirmed there have been at least three cases this year in which an increase in rail temperature caused delays or service disruptions, up from only one case last year.

¡°Especially recently, temperatures have been rising significantly, and as a result, the rails are also getting very hot,¡± Fujii said. ¡°This has led to instances, for example, where the tracks have become warped, which is why we decided to make an announcement on this matter.¡±

Similar cases have been reported this year on train lines across the nation, including the Yosan Line of Shikoku Railway (JR Shikoku), as well as the Kishin, Seto-Ohashi and Geibi lines run by West Japan Railway.

Train tracks are normally built to tolerate temperatures of up to 60 degrees Celsius. Railway companies routinely monitor temperatures and take steps to ensure safety if the temperature surpasses that threshold.

¡°It depends on the situation, but we do take emergency measures, such as spraying water to prevent the rail temperature from rising any further,¡± said Renina Yamaoka, a spokesperson for the JR Shikoku.

After such cases were reported on July 7 and 8, for example, the company temporarily restored the tracks by straightening the bent rails and replenishing the track¡¯s ballast, Yamaoka said. Services then resumed operations at a significantly reduced speed of 15 kilometers per hour.

Proper restoration work was undertaken after the last train of the day, which involved cutting the rails, adding joints to relieve the force causing the rail to expand, and then adding more ballast to counteract that force, thereby securing the rails firmly in place.

On JR Shikoku¡¯s lines, there were three cases of warped rails in July and two cases last year, while no such cases were reported from 2014 to 2022, Yamaoka said.