Tokyo conducted a large-scale highway test aimed at easing traffic on Wednesday, exactly a year before the start of the Tokyo Olympics, as it seeks to ensure smooth passage of vehicles during the quadrennial sporting event.

While the Metropolitan Expressway flowed more smoothly than usual due to restricted inflows, traffic jams emerged on the Tomei and Tohoku expressways, and a number of vehicles were seen making a turnaround before closed gates.

Experts believe that without countermeasures, traffic congestion on expressways would double during the 2020 Olympics between July 24 and Aug. 9, followed by the Paralympics from Aug. 25 to Sept. 6 in the Tokyo metropolitan area.

The full-day test involving major highways in the capital and neighboring areas, which started at midnight, is aimed at finding ways to achieve a reduction of up to 30 percent in traffic during the Summer Games.

Some 30 entry points to the Metropolitan Expressway were closed at one point, while four entrance and exit points on the expressway that lead to areas near event locations, including the New National Stadium and the athletes' village, were closed throughout the day.

The number of lanes bound for central Tokyo at 11 major tollgates on the expressway and other highways linked to it were reduced, and green traffic signals were shortened in duration at about 120 places on one of the major ring roads for a half day.

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"I learnt of the traffic restrictions today," said a 77-year-old male taxi driver who was driving near the athlete's village in the waterfront area. "I don't know how I'll explain this to customers who are in a rush to get to the airport."

The same test will be carried out on Friday, when traffic is heavier than normal.

Given the Tomei Expressway was temporarily congested for 15 kilometers and Tohoku Expressway for 6 km, Tokyo plans to implement a "road pricing" system that adjusts highway tolls depending on the time of day.

Under the plan, drivers on designated highways will have to pay an additional 1,000 yen ($9) between 6 a.m. and 10 p.m. Those travelling through the capital between midnight and 4 a.m. will have the usual cost halved.

"We are most afraid of confusion caused by chronic congestion, so we have to seek understanding" of the road pricing system from the public, said a senior transport ministry official who recognized that the plan places a heavy burden on commuters.

Other Olympic host cities have implemented restrictions, setting up lanes for exclusive use by participants of the Games and rationing use by private vehicles to alternate days depending on whether license plates are odd or even.

However, such a plan was not deemed viable for Tokyo as the number of lanes on the Metropolitan Expressway is relatively small.

On Wednesday, Tokyo also started a test to see whether commuting by boat would be effective in reducing road traffic and crowded trains.

In the eight-day test through Aug. 2, excluding the weekend, six small vessels, each capable of carrying up to 40 people, will shuttle between Tokyo's Nihombashi and Harumi areas every 15 minutes free of charge between 7:30 a.m. and 9 a.m.

The travel time is about 30 minutes, not much different from using trains or buses and some 1,500 people had reserved the services as of Monday. The Tokyo metropolitan government said it will study the feasibility of boat commuting based on a questionnaire survey of users.

Major railway and subway operators in the metropolitan area plan to extend operating hours during the games, while companies are encouraged to adjust their distribution routes and have employees work from home.

The central government held an event in Tokyo to promote telecommuting after it launched on Monday the "Telework Days" campaign through Sept. 6, under which 600,000 participants at 3,000 companies and organizations are expected to work remotely.

Mitsui Sumitomo Insurance Co., a participant in the campaign, said it will allow 5,500 of its Tokyo-based employees to telecommute, and Toyota Motor Corp. said it will allow 1,600 to do the same for four days.

Office equipment maker Ricoh Co. has said it will close its headquarters in the capital during the Summer Games, allowing 2,000 employees to work from home.