While the city is digging deeper to make room for more metro lines, shops, and public shelters, it will also welcome something truly ecological in the near future: its first underground park.

Local architects have already begun working on the project, and if it proves feasible, a green park covering hundreds of square meters will be built beneath the city in three years, the first of its kind in the entire country.

The park will not only consist of grass lawns and green vegetation, but also winding streams, according to Shu Yu, deputy director of the Shanghai Urban Underground Space Development Institute, and a researcher involved in the ecological project.

"We will probably landscape an existing underground facility in Shanghai to make it resemble a normal park above the ground," Shu said.

"Green areas will be extended from the ground to the walls and ceilings of the subterranean structure, and some indoor plants, such as the broadleaf bracket-plant, will also be used."

Architects plan to make the underground park look like a small forest, but the design still has some technical problems to overcome, such as adequate water supply and sunlight.

"We are considering using a sunlight receiver and transmitter," Shu said.

The sun's rays will be stored by a receiver above the ground and then transmitted to the underground park through optical fibers, where it will be converted into sunshine.

"For water supply, we could use special tubes to carry the water directly to the roots of plants," Shu said.

Green areas have generally been ignored in the city's existing underground spaces, most of which are developed for traffic and pedestrian use.

The underground park is expected not only to clean the air and regulate the temperature, but also to make for a relaxing and comfortable environment, architects said.

(China Daily March 15, 2007)