A test of traffic restrictions for next year's Olympics and Paralympics caused heavy road congestion in and around Tokyo.
The trial was conducted for two days in July. A traffic data company analyzed the records of about 30,000 trucks that used the metropolitan expressway system and national roads.
The length of bumper-to-bumper vehicles on national roads reached 80 kilometers on July 24, and 90 kilometers on July 26. That was 20 to 50 percent longer than usual.
The congestion was especially serious outside Ring Road Number Seven, where traffic lights were adjusted to restrict the flow of traffic into central Tokyo.
On National Highway Number Four, half of a roughly eight-kilometer stretch between two key intersections was jammed.
The line of jam-packed cars was about twice as long as usual. It took about 45 minutes to pass through that section -- about three times longer than normal.
In areas inside Ring Road Number Seven, the line of back-to-back vehicles was up to 30 percent longer than usual.
Professor Tetsuro Hyodo of the Tokyo University of Marine Science and Technology is a logistics expert.
He warns that heavy congestion during the Games could disrupt the delivery of supplies and seriously impact people's lives. He stresses the need for measures to reduce the volume of traffic.