The four expressway public corporations were privatized Saturday, 4 1/2 years after Prime Minister Junichiro Koizumi launched his structural reform initiatives to transfer as many public operations to the private sector as possible.

Japan Highway Public Corp. was split into three regional companies, while the other three -- the Metropolitan Expressway Public Corp., Hanshin Expressway Public Corp. and Honshu-Shikoku Bridge Authority -- were kept intact as private companies.

The six companies, whose shares are currently all held by the national and local authorities, are primarily tasked with managing expressways and collecting tolls.

Although tolls will remain unchanged after privatization, the new companies in charge of the Tokyo and Osaka regions immediately introduced discounts of up to 20 percent for users of the ETC electronic toll collection system.

The six private companies will conclude agreements with a new independent administrative agency -- also inaugurated Saturday to manage assets and debts from the four privatized public entities -- by March on new construction projects and expressway leasing.