During the Spring Festival travel rush, engineers from China Railway Corp work long hours to support its online ticket booking system.

About 30 people keep an eye on their screens or make phone calls to sort out technical problems at the national monitoring center of 12306.cn, the booking website, which is based at the China Academy of Railway Sciences in Beijing.

"Normally, we start working at 8 am and finish at 6 pm. However, during the 40-day travel rush (which continues this year to March 12), we begin at 6 am and leave the office at 11 pm, which is in line with the website's operating time," said Wang Tuo, an R&D engineer at the center.

An estimated 390 million train trips are expected to be made during the travel peak, up by 8.8 percent from 2017, according to CRC.

"The center is responsible for monitoring a real-time ticket system situation at 18 local railway bureaus around the country.

"There are mainly three parts of routine maintenance: taking phone calls from local railway stations and customer service in response to technical questions, monitoring the systemic bugs on the computer and inspecting machine rooms," Wang said.

"My job is to monitor and do some troubleshooting whenever an alarm is received. Cooperation and communication between different parts are needed, so we are in a central office," he added.

Three screens in the center occupy half of one wall and keep updating information for the day on the remaining orders to be processed, the total number and travel range of tickets sold and the proportion of order requests that may have risks.

According to Zhu Jiansheng, deputy director of the computing technologies institute at the academy, the system can sell up to 700 tickets a second, and there is a little pressure during normal times.

"However, it is kind of a burden during Spring Festival because the destinations and departures largely focus on megacities like Beijing, Shanghai, Guangzhou and Shenzhen," Zhu said.

"For this year, we have expanded the ticket pool from 10 million to 15 million per day. The 12306 app has also been upgraded," he added.

Shan Xinghua, technical head of 12306.cn, said that to deal with the stress, the website has removed 90 percent of the pictorial verifications for tickets to some of the hottest destinations, and risky requests made by some third-party booking applications were blocked from the system to streamline the purchasing process.

"It is just like on the highway. A speeding car that poses a threat to others should be slowed down. Those apps refresh the website too fast and cause damage," she said, adding the third-party apps are moved to a slower line.