Railway engineer Yang Guoyu and his peers have been knocking on the bolts and measuring the track gauge on a railway in Haining City, Zhejiang Province for half an hour in the summer heat.

To fully complete the check of the track, it'll take them at least three and a half hours. The summer heat has made its impact in many industries, including on China's rail network.

In the sweltering summer, all the components of the railway system are pushed to the limit, and this makes the track check more necessary than ever.

"The steel tracks are prone to expand under the influence of extremely high temperatures," said an expert in rail tracks at Yanguan station of Hangzhou-Haining intercity railway, "which makes the track easy to break due to the uneven force when running on the track, causing significant consequences such as derailment."

We must kill potential expansion in the bud, before it's too late, he added.

Besides for the frequent track checks conducted by the workers, fasteners containing clips, clamps and joints are crucial parts needed to affix the rails to the concrete railway sleepers. The gravel under the tracks can also help to absorb the shock and buffer the impact when the trains are in operation.

The engineers took the local temperatures into consideration and set up a suitable plan to lay the tracks, leaving enough space for the tracks to expand in scorching temperatures, while also pouring water on the tracks to keep them cool. "Then we can keep the steel tracks stable," said Wang Liwang, a deputy head of a railway section at China Railway Beijing Group.