Xu comes from Central China's Henan province, and has been working in Shanghai since 2007. He is a truck driver for a logistics company and has worked part-time at the expo since October.

He has another job, working the nightshift as a security guard at the nearby Hongqiao International Airport.

"Otherwise, how can I make a living for my family?" said Xu, whose wife also is a migrant worker selling clothes in Shanghai. They have a 4-year-old son who just started kindergarten in their hometown of Shangqiu, Henan.

There are six buses circling the venue, and each one has only eight seats.

"It's rough since we are outnumbered, so we try to drive fast to ferry more people around," Xu said. "I don't mind working long hours, as long as the ride saves others' time."