As the subway system in China's capital continues to add lines and stations and conveniences, photographer Wei Xiaohao climbs aboard with a record-setting crowd.

As of March 8, the total number of passengers on Beijing's 16-line metro service has topped more than 10 million per day, officially making it the busiest subway in the world. For only 2 yuan ($0.32), you can ride anywhere on the entire 442-km system, except for the airport express (25 yuan). As part of many people's everyday routine, the subway offers a peek into the lifestyle of modern city-dwellers.

Taking a nap in the crowded carriage seems to require special technique.