Metropolitan Express Public Corp. sank 35.7 billion yen into an assortment of projects to fix chronic congestion on Tokyo expressways, only to find that the money did little to remove the bottlenecks, according to a government audit report Monday.

The Board of Audit report says the investment covered 20 projects, including building additional exits and toll gates, and widening junctions, to try to improve flow on the heavily used road network, which accommodates more than 1 million vehicles each month.

Some of the least efficient projects cited include a 250 million yen upgrade to widen the Ariake junction, where traffic usually backs up 2 km.

The widened junction, in use since March 1999, reduced congestion for a while. But according to an October 2000 survey, the situation soon returned to what it was before the project.

Another project of doubtful efficacy, the Board of Audit report says, is the construction of additional lanes at the Oi toll station.

Costing 160 million yen, the work reduced congestion at the toll station but created new bottlenecks inside the Tokyo tunnel.

In another fix-it project, Metropolitan Express sought to alleviate traffic congestion in the Takebashi junction in central Tokyo by building an additional exit at Hitotsubashi, at a cost of 1.9 billion yen.

Before the Hitotsubashi exit was built, backups in the area extended about 6.4 km. The new exit reduced this by a few hundred meters.

According to Metropolitan Express officials, the chronic congestion on Tokyo's expressways is caused by the large volume of through traffic. They say congestion will not be significantly reduced until construction of the Chuo Kanjo expressway, a new beltway that rings outer Tokyo, is completed.