August 7 will probably go down in history as the hottest day of this year. Air temperature in Kyiv reached +39 C in some places. But heat causes suffering not only for people and animals. High temperature is also a challenge for infrastructure: power lines, vehicles, rail track.

Hot weather causes discomfort for passengers - people often complain about heat and fug in train cars. No surprise, as out of 5 thousand cars only 2 thousand are equipped with air conditioning systems. 

However, the railway workers are more worried about high temperature not inside a car, but outside it, namely the temperature of rails.

Physics law says that all matters have a tendency to change in volume in response to a change in temperature. Leading engineer of Ukrzaliznytsia Vasyl Yakovlev says that with the temperature change of 10 degrees the length of rails changes by one millimeter per every hundred meters of the track.

"Old end-to-end tracks suffer the temperature fluctuations less, as the length of every rail part is short and the thermal expansion is compensated by joints, while jointless rails change significantly. We have a jointless part of track 28 km in length. When the temperature increases by 10 degrees the rails become 2.8 meters longer," the engineer explained.

Temperature fluctuations are taken into account in every rail track project, but when the temperature becomes too low or too high, there is still la risk of buckle of rail: straight rails may turn into a "snake", holdfasts between rails and cross-ties may loosen. All this poses a risk to the rail traffic security.

Yakovlev says that potentially dangerous temperatures are -25 C and lower and +39 C and higher. Under such conditions, the rail brigades work in the emergency mode: workers inspect the tracks every two hours and measure the temperature of the rail surface. If a track heats up over +50 C, the traffic on this part gets limited - a dispatch informs engine drivers about speed limit of 60 km/h.

The leading engineer told ForUm that the temperature is monitored on 180 stationary posts. There have been 15 cases of limited traffic registered this summer due to the heat.

To see the process of track inspections for itself, ForUm went to one of the Kyiv tracks. Near the road crossing, there is a special thermometer installed next to the rails, which shows +47 C. Local master Volodymyr Andrusenko says that at stationary posts the temperature is checked every hour, and the results go in a special journal and are reported to the dispatch.

Masters of the local rail posts also patrol the track every two hours to record the temperature. Regardless of the season, special measuring cars inspect the tracks four times per month and check the condition of the rails with special equipment.

The master on duty Maria Ostapchuk demonstrated how to check the temperature of the functioning rails. The difference in temperature between the functioning rail and test rail is explained by the color: the test rail is black, hence gets heated up faster.

An interesting fact is that the rail highest temperature ever was registered not in Crimea, as one can suppose, but in Kamenets-Podolski and made +62 C. The minimal registered temperature on Ukraine's territory made -47 C.

Whims of nature sometimes force to make corrections in our activity, and traffic limitations are obviously a good decision. As the saying goes, "slow but safe".  However, we doubt that in Spain or France, where summers are hotter than in Ukraine, the speed trains have to slow down to 60 km/h. But this is a different story.

Dmytro Khyliuk, photos by Viktor Kovalchuk


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