The city government plans to build up to 800 kilometers of electric streetcar lines in the city's outer districts, local media reported Wednesday.

The Shanghai Municipal Development and Reform Commission announced on its microblog Sunday that between 600 kilometers and 800 kilometers of streetcar lines will be laid in the outer districts to meet the transportation needs of local residents, the Wenhui Daily reported.

Under the current plan, the streetcar network will cover more ground than the city's 600 kilometers of subway lines by 2015.

"Modern streetcars can carry more passengers than city buses, and they cost much less to build than subway lines," said Shi Xiaofa, a professor of transportation engineering from Tongji University. "It is also a more environmentally friendly form of public transportation than a city bus because it is electrically powered."

A typical streetcar runs on tracks built into the roadway, allowing other vehicles to drive on the same pavement, Shi told the Global Times. It is powered by electric lines that hang above the tracks.

A streetcar system can carry anywhere from 6,000 to 15,000 passengers per hour, compared with the city bus system, which transports about 5,000 passengers per hour, according to the commission. Building a streetcar line requires about one-third of the investment needed for a subway line and takes far less time to construct.

The Shanghai Municipal Transport and Port Authority has not yet decided where the streetcar routes will be built, the Wenhui Daily reported.

Shanghai built its first modern streetcar line in 2009 in the Zhangjiang High-Tech Park in Pudong New Area.

An unnamed employee from the streetcar's operator said that the project has been running a deficit because of high maintenance costs and a lack of riders during off-peak hours, the Wenhui Daily reported.

Authorities need to carefully consider issues such as passenger volume and the environment along a planned route before making construction plans because a streetcar system costs more than running city buses, Chen Bizhuang, an expert from a research institute under the Shanghai Urban Construction and Communications Commission, told the Wenhui Daily.