View of crowded Sihui East station on Subway Line One in Beijing on the first morning after the fare hike on Dec 29, 2014. According to reports, the number of passengers dropped by only 10 percent on Sunday, the first day the fare system was in force. [Photo/IC]

"What's more, many passengers came up asking how they can get a discount. They seemed confused but very concerned about the discounts,"said the worker.

According to Beijing Youth Daily, four lines opened on Sunday, namely Line 7, Line 14 (East Part), and sections of Line 15 and the Line 6 were extended. The four new lines adopted the same security check system as airports. Not only passengers' bags and belongings will go through the x-ray check, but they will also be frisked.