The debts of two public corporations that operate major bridge and road systems are snowballing as traffic continues to fall far short of initial estimates, a government inspection report warned Tuesday.

The Honshu-Shikoku Bridge Authority, which operates three roads and bridges linking Honshu and Shikoku, is saddled with 4.37 trillion yen in debt, but has assets of only 3.53 trillion yen, the Management and Coordination Agency said. As of the end of March 1999, it had 837.7 billion yen in negative net worth.

Likewise, Japan Highway Public Corp., which operates the Aqualine expressway that runs beneath Tokyo Bay to connect Kawasaki and Kisarazu, Chiba, has been spending 316 yen to make 100 yen in revenue, the agency said. Traffic volume on the Aqualine is 31 percent of what the public corporation had estimated, the agency said.

"It has become almost impossible to secure income as planned in the (debt) redemption program," the report says of the Aqualine.

Pointing out that both operators are having difficulties covering road maintenance fees, the agency called on the Construction Ministry to offer guidance to the two quasigovernmental bodies to improve their management and introduce cost-cutting measures to make their routes profitable.

The report, which analyzes the management of Japan's toll roads, has been compiled by the agency's Administrative Inspection Bureau.

Traffic volume on 42 of the 58 toll highways operated by Japan Highway Public Corp. has proved to be less than the corporation's predictions, with 26 of the highways now operating in the red, the report says.

Of the 26, 13 have seen less than half of their forecast traffic volume, it says.

The report strongly urges the Construction Ministry, which plans and constructs toll expressways through the affiliated corporation, to improve the accuracy and transparency of traffic volume prediction and necessary investment.

In the case of the Aqualine, an average of only 11,876 vehicles used the road each day in its first year. That figure fell to 9,996 in 1998 and 9,651 in 1999.

The first year's figure was just 47 percent of the demand predicted in 1997, and that fell to 35 percent in 1988 and 31 percent the following year.

In 1987, the corporation predicted daily traffic of 33,000 vehicles during the first year and 64,000 in the 20th year.

Just before its opening in 1997, the original prediction was revised downward to 25,000 for the first year - a figure that was also unrealistically high - and 53,000 for the 20th year, which is considered unlikely.

The Honshu-Shikoku Bridge Authority has revised its redemption programs and traffic volume predictions twice since 1988, but real traffic volume has always proved much less than predicted.

The Aqualine began operating in December 1997, while the Honshu-Shikoku road-and-bridge system was completed in May 1999.