A plan is being mulled to build another ring-line subway to alleviate the pressure to the Metro Line 4 which is the only ring-shaped Metro line of the city, the city's top planning official said today.

　　The new ring line that is still under planning will be built underground near the Middle-ring road to make it more convenient to transfer among the city's subway network, Shi Jiaming, deputy director of the Shanghai Urban Planning and Land Management Administration told Shanghai daily.

　　“To save the cost, the new line will share stations on some current subway lines to form a new ring route," Shi said. "It will be a 'virtual ring' to be unlike the current Line 4 that is coherent through its way.”

　　The Line 5, for instance, could be extended further to the north to connect with the Line 2 to be part of the west section of the new ring, he said.

　　A previous plan to separate Line 3 that shares stations with ring-shaped line 4 has been aborted because of its estimated huge cost, he said.

　　Shanghai plans to build a total of 930 kilometers of subway lines in downtown area by 2040 with another 930 kilometers of subway and railway lines set up in suburb regions, Shi said.