The Shanghai-Hangzhou HSR Line started to operate in 2010. A photographer followed the workers during the building period and below is a link to a slideshow. These guys are called Migrant Workers since they come from remote provinces, their work is dangerous with long work hours and low salary. Still, its better than staying home in the countryside without any possibillity to find a job other than to be a farmer. These hard working gentlemen are the backbone in the great leap forward for High-Speed Rail in China.
More info about this railway line: