What is a right-turn-only traffic signal?

At the corners of large intersections, mainly in Tokyo, you may sometimes see vertical traffic signals facing diagonally. Because the lighting cycle can seem strange at first glance, some drivers may be confused about who the signal is for. This article explains the purpose of these traffic signals and which drivers they are intended for.

Installation appearance

On wide roads, such as those with highways or overpasses in the center, it can be difficult for vehicles in the right-turn lane to see the traffic signals in their normal positions. Therefore, a "right-turn-only" traffic signal is sometimes installed diagonally where it is easier for vehicles in the right-turn lane to see.

Auxiliary signal for right turns at wide intersections

Most right-turn-only traffic signals are installed vertically. Depending on whether they are installed on the left or right side of the signal pole, the side on which the arrow signal is placed may vary.

In some cases, they may be installed in the normal orientation. In these instances, the right-turn lane is often independent of other traffic lanes, and there may be no "right-turn-only" sign.

Signal cycle

The cycle of a right-turn-only traffic signal varies slightly depending on whether it uses a time-difference system or a right-turn separation system. The following is an example.

Normal case

In the case of a time-difference system

In the case of a right-turn separation system

In the case of a right-turn separation + time-difference system

There are also left-turn-only signals

Although they are much rarer than right-turn-only signals, there are also things called "left-turn-only signals."

For example, the example above is a station rotary where you can proceed in the direction of the rotary without a signal, and there is a signal only on the left side (because there is a pedestrian crossing ahead).

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Please take a look at this as well.