The maximum possible speed limit on the country's major expressways will be raised from 100 kph to 120 kph, it was announced Thursday, marking the first increase since the 1963 opening of Japan's first highway.

Trucks and other large freight vehicles will not be subject to the change, meaning their maximum speed limit will remain at 80 kph, according to the decision by the National Police Agency.

The new 120-kph limit will apply to expressways built with gentler slopes and curves. They include the Tohoku, Kanetsu, Joban, Tomei, Shintomei and Kyushu expressways.

However, after the NPA changes the traffic regulations it will be up to local public safety commissions to set the actual speed limits for their relevant expressways.

The commissions in Iwate and Shizuoka prefectures are already considering testing a 110-kph limit from as early as next year on parts of the Tohoku and Shintomei expressways, respectively, with plans to expand this.

The decision is in line with recommendations made by a research panel comprising officials from the transport ministry, the NPA and highway regulation experts.

In reaching its conclusion, the panel analyzed driving speeds and accidents on expressways over the past three years. It found that raising the limit would not result in an increase in accidents if measures were taken to prevent violations of the new rule.