A car pulls off at the Laibin South Highway Toll Station in Guangxi Zhuang Autonomous Region on Dec 16, 2014. [Photo/Xinhua]

The limit on the number of years tolls can be charged on highways is to be removed, allowing local governments to pay off debts incurred in road construction, according to a rule revision proposed by China's transport authorities.

The current Toll Road Management Regulation stipulates that tolls can only be charged for between 15 and 30 years, depending on how the road is financed.

The revised version says that for highways needing a longer period to recoup investment the toll period could be extended beyond 30 years.

The transport ministry will seek public opinions until August 20.

By the end of last year, the Chinese mainland had 162,600 km of roads charging tolls, including 106,700 km of toll expressways. The total length of the expressways is the longest in the world.

A report by the transport ministry showed that toll collection stood at 365 billion yuan in 2013 while expenditure reached 431 billion yuan, leading to a loss of 66 billion yuan ($10.66 billion).

Fees collected were mainly used to make principal and interest payments related to construction, with the remainder covering maintenance, taxes and overheads, the report said.

Wang Tai, deputy director of the transport ministry's highway bureau, said it was "reasonable" to collect tolls because taxes and public financing alone could not cover all the costs.

The proposed time extension has already caused controversy, with some questioning whether toll roads will become "cash machines" for local governments.

Some think losses made by local authorities in constructing roads should not be paid by drivers but there are those who say the extension of toll-charging will help ease traffic congestion.

Zhao Jian, a professor at Beijing Jiaotong University, said China built the world's longest expressway network in a short period meaning that the majority of roads run at a loss, Chinanews.com reported.

He believes it unnecessary to fear toll roads will become "cash machines" because tolls collected could not pay the debts.

Zhao said to meet the costs of road management and maintenance and pay off debts for construction, tolls will continue to be collected in the long run.

Zhang Zhuting, a professor specializing in traffic laws at the Management College of the Ministry of Transport, said a major change proposed is that the government will issue bonds to raise funds for highway infrastructure projects rather than borrowing from banks.