What is the order of the 'dumplings' for regulatory and instruction signs?

According to the 2025 edition of the White Paper on Traffic Safety published by the Cabinet Office, the number of regulatory and instruction signs installed nationwide is approximately 9.39 million. Additionally, according to the 2024 White Paper on Police from the National Police Agency, the number of road signs (regulatory and instruction signs under the jurisdiction of the National Police Agency) installed is approximately 5.97 million. Many of these consist of multiple signs installed on a single post, but did you know that these signs are installed on a single post in a specific order according to certain rules? In this article, we will take a detailed look at the rules for installing multiple signs.

Installation patterns for main signs

This is a slight digression, but there is a slope called Dango-zaka (Dumpling Slope) in Bunkyo Ward, Tokyo. Near the "Dangozaka-shita" intersection at the bottom of Dango-zaka, there is a regulatory sign assembly where three main signs are installed on a single post, which looks exactly like a "dango" (dumpling). Therefore, the appearance of multiple traffic signs being "skewered" on a post is sometimes described as being "in a dango-like state."

Regarding this dango of signs, detailed rules for installation are stipulated in the Traffic Regulation Standards issued by the National Police Agency. For example, let's extract some characteristic points.

* Looking at the actual situation, there are quite a few cases where there are four main signs even if there are multiple separate auxiliary signs, so it seems that "four or fewer main signs on the same plane" is the de facto rule.

The Traffic Regulation Standards provide the following diagram as a specific example of multiple main signs being installed on a single post. This is for when the post is on the left side of the road in the direction of travel. (If it is on the right side due to a median strip or one-way traffic, the left and right are reversed.)

The numbers within the signs represent the order of "array priority" which will be discussed later. In other words, the rule is that those with higher array priority are installed higher up and to the right. This is likely to make those with higher array priority more conspicuous..

Also, the regulations differ depending on the presence or absence of "Pedestrian Crossing," "Bicycle Crossing Lane," and "Pedestrian Crossing/Bicycle Crossing Lane" signs (hereinafter abbreviated as "Pedestrian Crossing, etc."), and the rule is that if there is a "Pedestrian Crossing, etc." sign, it must be installed at the very bottom on the road side. "Pedestrian Crossing, etc." signs are always placed at the bottom, but by ensuring they are placed on the road side, it is likely intended to guarantee they are visible to a certain extent.

＊

Also, thinking according to this rule, although not illustrated, it can be deduced that if the number of main signs increases, the arrangement will be as follows.

When the number of main signs becomes four, it is extremely rare for them to be arranged in a single vertical column. In other words, while it would theoretically be the arrangement below, it is almost never seen in reality.

Also, as an exception to the placement method, although not stipulated in the Traffic Regulation Standards, a relatively common case is when one wants to indicate "End" and "Continuation/Start" on a single post, the "End" sign is placed on the left side. The reason is likely that there is less need to make the sign that is ending stand out compared to the one that is continuing or starting.

In the case of overhead/overhang types, signs are arranged horizontally in a row. In this instance, similar to the "red," "yellow," and "green" of traffic lights, the ranking is higher toward the right. Even if the support pole for an overhang type is on the right side of the road, it does not become symmetrical; the ranking increases as you go to the right.

Incidentally, note that this ranking only applies to "regulatory signs" and "instruction signs". "Guide signs" and "warning signs" are installed by road administrators, so they are not subject to this ranking and, except under special conditions, are not installed stacked on the same pole.

Ranking of main signs

Now, let's look at how the "ranking," which is the number on the sign, is determined based on the type of sign.

There is a ranking from 1 to 45. It is divided into five categories, and categories higher up are more important and need to be more prominent.

• Related to stopping or slowing down (1-3)

• Related to prohibition/restriction of passage (4-21)

• Related to restrictions on turning right or left at intersections, etc. (22-25)

• Related to methods of passage, etc. (26-39)

• Related to parking (40-45)

The specific items belonging to each category are as follows.

(*Note that for No U-turn (23/34) and Sound Horn/Horn Zone (26/36), the ranking differs depending on whether they are used for point regulation or section regulation with the same regulatory sign.)

■ Related to stopping or slowing down (1-3)

■ Related to prohibition/restriction of passage (4-21)

■ Regarding restrictions on turning at intersections, etc. (22-25)

■ Regarding methods of passage, etc. (26-39)

■ Regarding parking (40-45)

Note that among regulatory and instruction signs, the following are not listed in the table of arrangement order. It seems that these are basically installed on separate, independent sign posts, or if they are stacked, they are often installed in an order near where they are listed in the arrangement order within the surrounding same category.

Examples and differences by prefecture

Based on this, let's look at some general examples. I have arranged typical sign combinations based on installation patterns and arrangement order.

Incidentally, it is recommended to leave a gap of 0 to 1 cm between signs, but when an auxiliary sign is installed on a main sign, it is recommended to leave a gap of 10 to 15 cm between the main sign with the auxiliary sign and the main sign directly above it to prevent the misunderstanding that it applies to all main signs above.

*

Also, while all installers, such as prefectures and road corporations that manage motor vehicle-only roads, in principle install traffic signs according to these installation patterns and arrangement order, there are scattered cases where these principles are deviated from in fixed patterns.

The following are examples.

(1) Maximum speed limits and no-passing zones are ranked higher than prohibition of driving in other than specified directions (Chiba)
(2) No-passing zones are ranked higher than road closures (Chiba)
(3) One-way traffic is ranked at the very bottom (Osaka, Chiba)
(4) The ranking of time-restricted parking zones and no-parking zones is reversed (Osaka, parts of Kanagawa (Hiratsuka), Chiba, Yamanashi)

Characteristic ranking orders can also be seen in Aichi. (Refer to the article below)

When multiple sign installers are involved, signs may be installed in numbers that deviate from the above rules, or they may be installed in a way that does not follow the placement ranking or installation patterns.

*
Please take a look at this as well.