Photo/Illutration A roundabout installed in Kita-Kyushu’s Yahata-Higashi Ward (Asahi Shimbun file photo)

Road accidents resulting in death or injury have been cut in half by the introduction of roundabouts, or traffic circles with no stoplights, according to the National Police Agency (NPA).

Japan began establishing roundabouts after the revised Road Traffic Law took effect in September 2014.

As of March 31 this year, roundabouts were installed at 87 locations in 31 prefectures, according to the NPA.

In fiscal 2018, seven accidents resulting in death or injury occurred at 66 locations where roundabouts were installed by March that year, a survey found.

The figure compares with an annual average of 13.7 between fiscal 2015 and fiscal 2017. The survey excludes roundabouts built where there were no traffic intersections.

At 44 locations where roundabouts replaced rotary intersections, annual accidents resulting in death or injury fell from 6.33 to five.

At the remaining 22 spots where roundabouts replaced standard intersections, the figure dropped from 7.37 to two.

Miyagi Prefecture has introduced 20 roundabouts, the most in Japan, citing that they can be used as usual during disasters since they don't require stoplights.

Nagano Prefecture has the next highest number, with seven, Aichi Prefecture has six, Shizuoka and Osaka prefectures have five each and Saitama Prefecture has four.

Drivers entering a roundabout must slow and yield to vehicles already inside it. When exiting, they must slow again and keep to the left. They must also stop for pedestrians using crosswalks on roads that branch off from the roundabout.

Roundabouts in Western countries have been cited as effective in preventing serious accidents since people can't drive fast in them.

However, roundabouts are prone to congestion under high volumes of traffic and are better suited for residential roads in suburban areas, where there are fewer pedestrians, back roads in urban areas and expressway exits.

One twist to their introduction is that while residents often complain of noise generated by vehicles passing through neighborhood roads, roundabouts have drawn concern for reducing the engine noise of vehicles.

In June and July, the Japan Federation of the Blind asked the NPA and the transport ministry not to install roundabouts, saying that the engine noise of vehicles traveling at lower speeds on roundabouts isn't loud enough to alert blind pedestrians of their approach.

The group also pointed out that crosswalks on roads that branch off from the roundabouts don't have stoplights.

“Roundabouts are designed for (the convenience of) cars, so they pose a danger to those with visual impairments,” a member of the federation said.

Police said they and road administrators have taken actions to ensure that roundabouts are safe to those pedestrians.

Signs are posted informing drivers of the rules of using roundabouts, including that they must yield the right of way to pedestrians, and the surfaces of roundabout roads are roughened using such methods as grooving, so vehicles will make more noise when their wheels pass over it.

“We will promote the introduction of roundabouts at appropriate places by cooperating with road administrators,” an NPA official said.