In this undated photo, police officers patrol the square at Beijing Railway Station. (ZOU HONG / CHINA DAILY)

BEIJING - The iconic big bells of Beijing Railway Station ushered in this year's Spring Festival travel rush on Thursday, which is scheduled to last until March 8.

The bells peal out at hourly intervals from 6 am to 9 pm, playing the folk song lauding Chairman Mao, "Dongfanghong"

Housed in the downtown railway station, about 3 km away from Tian'anmen Square, the twin turret clocks were built in 1959 and have ticked away over six decades with unequaled accuracy.

The bells peal out at hourly intervals from 6 am to 9 pm, playing the folk song lauding Chairman Mao, "Dongfanghong."

The tower clocks became Zhang Bing's responsibility after the 60-year-old maintenance technician landed the job in 1980.

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Every two hours, Zhang and his colleagues patrol around the timekeepers to check the mechanical components. Initially, the clocks relied on several sets of gears weighing more than 100 kg, and Zhang had to worm his way into the cumbersome machinery to remedy any problems. In summer, he often sweats buckets due to the muggy heat inside.

Later on, the tower clocks were given an electronic facelift. During preparations for the 2008 Beijing Olympic Games, GPS signals and the BeiDou Navigation Satellite System equipped the antique bells with automated synchronizers, easing the burden for the aged guardian.

"I attend to the clocks as if they were my own children. I dare not be slack, because travelers shuttling back and forth would be misled if the clocks ran a little slow or a couple of minutes ahead," Zhang said.

These days, the time is everywhere: not just on clocks or watches, but on phones and computers. However, the antique bells used to be the main way for travelers to keep track of their departure and arrival. The tips of the minute hands were designed to be slightly bent in order to help people tell the exact time when they are looking up at the clocks in different directions from the square.

Zhang is one of the capital city's masters of miniaturization, detectors, and correctors of clock errors. In guarding the tower clocks, he also helps preserve the history of the city.

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He will soon retire in June, but he never stopped learning new skills and technologies from both his fellows and other clockmakers.

Wang Qi, 28, one of Zhang's apprentices, came to Beijing on her own in 2013. Taking over the responsibility of guarding the twin clocks in the near future weighs on the mind of the young woman and her colleagues. They strive to emulate their master's feat of ensuring the familiar ding-dong of the bells continues to ring out.

"All our hard work will prove worthwhile as long as the bells ring out promptly and loudly," Zhang said.