While there might not be anything special about the construction of the city's first metro line, there certainly is about the installation of the country's (and possibly the world's) first ever toilet inside a tunnel-boring machine (TBM).

For those who operate the mechanical giant that's carving the tunnels for the Shenyang metro - it's 48 meters long and stands more than 6 meters high - it's not always easy to answer the call of nature, especially when you're working 20 meters underground. So the special convenience has brought sweet relief.

The new toilet, which is making its debut in the northeast China city in Liaoning Province, can be used for three months without the need for cleaning, as it features an environmentally friendly design that consumes very little water, Wang Jiayi, president of the Shenyang Zhengchang Environmental Protection Company, said.

But such luxuries do not come cheap. The TBM toilet costs more than 20,000 yuan (US$2,600), Xiao Hui, director of the China Railway No 9 Group Co Ltd, which is responsible for the metro project, said.

However, the handy little device will be a huge benefit to the 3,300 people working on the project underground, and that will improve efficiency, he said.

Lin Muxi, an economist from Liaoning University, said: "The project will play a big role in easing the ever worsening urban congestion, as well as helping the economy."

After decades of seeing its applications rejected, Shenyang finally obtained approval from the State Council in 2005 to build the 182 km metro.

The first phase, which is currently underway, will cost 17 billion yuan (US$2.2 billion) and is scheduled for completion in 2012.

"A subway is one of the most important symbols of a modern city. It will help improve the city's reputation and attract investment," Chen Zhenggao, the city's party chief, said.

Shenyang is set to become the country's seventh city to boast a metro, after Beijing, Shanghai, Shenzhen, Nanjing, Guangzhou and Tianjin.

Zhang Min, a saleswoman who lives on the outskirts of the city said she currently spends more than an hour every day commuting to work.

"That would become 20 minutes (when the metro is completed)," she said.

Zhang is also lucky to already have a flat close to the metro's Line 1, as property prices have soared 30 percent since the scheme was launched.

(China Daily April 4, 2007)