BEIJING, July 30 -- What's next in the toolbox of Chinese policy makers to support the economy? Look underground for the answer.

Authorities plan to build underground utility corridors in cities across the country and make it a national priority project, according to a statement released Wednesday after an executive meeting of the State Council, China's cabinet.

The tunnels will carry utility lines such as electricity, water, heat and sewer pipes as well as telecommunications and television cables, all collectively laid underground, the statement said.

China's urban underground infrastructure has long lagged behind and faces growing pressure due to extreme weather conditions, said Zou Shinian, a researcher at the State Information Center.

The utility tunnel project will improve city life, but more importantly, it can stimulate investment and create new growth momentum for the economy, Zou said.

China's economy expanded 7 percent year on year in the second quarter of this year, unchanged from the first quarter, but well below previous double-digit growth due to weaker domestic demand and foreign trade.

The economy still faces downside pressure and investment plays a significant role in propping up growth.

However, spending must avoid waste and low-quality growth. Underground infrastructure in Chinese cities, which is mostly outdated and sometimes dangerous, has become a reasonable target for investment.

ROAD ZIPPERS, LETHAL SEWERS

Chinese Premier Li Keqiang, who presided over the State Council meeting, once called underground infrastructure "the conscience of the city," echoing Victor Hugo's description of the Paris sewers.

Many cities look fancy and glimmering from the outside, but underground infrastructure is their common weakness, Li said during an inspection tour last year.

The construction of utility tunnels will help solve problems that have long plagued Chinese cities, such as "road zippers" and "overhead spider webs," said the State Council statement.

Road zippers refer to ditches below city roads that are often dug open for repairs and installation, disrupting traffic and local life. The spider webs -- webs of power lines and telecommunications cables spread overhead -- are also familiar scenes in Chinese cities.

Under extreme conditions, urban underground infrastructure can even be deadly.

In July 2012, the heaviest downpour in six decades hit Beijing and killed 79 people. Some drowned in basement homes. A driver drowned after being trapped for three hours in his submerged car under a downtown overpass.

The tragedy triggered public fury and prompted questions over the disparity between the city's faulty drainage system and its eye-catching skyscrapers.

Urging faster construction of underground utility corridors, Li criticized the country's strained urban sewers at the cabinet meeting: "A downpour could lead to massive flooding and citizens joked they could 'go sea-seeing' even in some big cities."

MULTI-BILLION-DOLLAR PROJECT

Construction of the tunnels must "ensure absolute safety" and should be expanded gradually across the country after being piloted in some cities, Li said.

The pilot cities include South China's Haikou, where 140 km of utility tunnels will be built with an investment of 3.6 billion yuan (580 million U.S. dollars).

Each pilot city is eligible for special subsidies, ranging from 300 million to 500 million yuan a year for a period of three years, according to a notice released by five ministries and departments in January.

Many local governments have already shifted the focus of their infrastructure investment underground, Shanghai-based newspaper China Business News reported Thursday.

Minister of Housing and Urban-Rural Development Chen Zhenggao said in April as much as 1 trillion yuan in investment would be needed if China builds 8,000 km of utility tunnels each year, not including indirect investment such as spending on steel, cement and machines.

One trillion yuan amounts to 2 percent of China's total fixed-asset investment last year and will be quite the sum of money, Chen said at a meeting, noting that the construction will be a good way to spur investment as choices have become limited.

The government will encourage private capital to participate in the construction and operation of utility tunnels by giving subsidies and soft loans, according to the State Council statement Wednesday.