Do you know Japan’s Chugoku region?
Chugoku is the region at the western end of Honshu. It consists of five prefectures: Tottori, Shimane, Okayama, Hiroshima, and Yamaguchi.
Roads run east and west along the Seto Inland Sea and Sea of Japan sides, while other roads cross the Chugoku Mountains to connect the two coasts.
What kinds of roads cross this region, and how many vehicles use them each day?
This article uses Japan’s Ministry of Land, Infrastructure, Transport and Tourism Road Traffic Census to present the Chugoku region’s road traffic volumes through a map and data.
Compare them with road conditions in your own country. What differences can we discover together?
Chugoku Region Road Traffic Volume Map
First, let us explore the Chugoku region’s roads on the map.
You can switch between expressway-category roads (expressways and urban expressways in this dataset), general national roads, prefectural roads, and surveyed city roads.
Select a circle to see the road name and traffic volume for that survey section. Switch between 2015 and 2021 to compare the same section across the two years.
This map does not show every road in the Chugoku region. It shows survey sections for which traffic volumes were published in the Ministry of Land, Infrastructure, Transport and Tourism Road Traffic Census.
How to use the map
- Use the road-category buttons to switch between expressway-category roads, general national roads, prefectural roads, and surveyed city roads.
- Zoom in to see individual circles representing traffic volumes.
- Compare traffic volumes by the size and color of the circles.
- Select a circle to see the weekday 24-hour traffic volume for that location in 2015 and 2021.
- The official basic road section to which the selected traffic volume applies is shown as a fluorescent green line with a dark outline. It does not represent the entire route.
- Search by route name, prefecture name, or survey-section name.
Sections shown on the map
The map shows 9,048 basic road sections across the five Chugoku prefectures whose representative locations and section lines could be verified using the ministry’s official web map.
These consist of 216 expressway-category sections, 2,668 general national road sections, 5,948 prefectural road sections, and 216 surveyed city road sections.
This is not a map of every local road. The city-road category includes only some major roads recorded in the national survey. Traffic surveys conducted independently by local governments have not been added.
Comparison with 2015
Of the 9,048 basic road sections shown on the map, 8,729 can be compared between 2015 and 2021.
Where no corresponding 2015 traffic volume was found in the official materials, only the 2021 figure is shown.
New roads and changes to section boundaries can make direct comparison between the two years impossible. Historical figures that could not be verified have not been estimated or filled in.
How Did Traffic on Chugoku’s Expressway-Category Roads Change?
Let us compare traffic on the Chugoku region’s expressway-category roads in 2015 and 2021.
Across the 215 basic road sections that can be compared in both years, the combined traffic volume decreased by 5.7%.
This total is not the number of individual vehicles driven in the Chugoku region. If the same vehicle passes through several survey sections, it is counted once in each section.
Compare the Seto Inland Sea and Sea of Japan Sides
The map shows roads running east and west along both the Seto Inland Sea and Sea of Japan sides of the Chugoku region.
Between them, other roads cross the Chugoku Mountains and connect the two coasts.
How does the pattern of circles differ between the coasts and the mountains? Switch between expressway-category roads, general national roads, prefectural roads, and surveyed city roads to compare them.
Follow Chugoku’s Roads for the First Time
You do not need to know the Chugoku region’s place names or road names in detail.
What stood out to me was how roads on the Seto Inland Sea and Sea of Japan sides are connected by routes crossing the Chugoku Mountains. Which coast would you start from?
Start by searching for a place you know, a place you have heard of, or somewhere you plan to visit for travel or business.
Select a circle nearby, check the road name and traffic volume, and then move the map to other parts of the region.
The map and data may help you discover a road in Chugoku that you have never encountered before.
Sources and Notes
- Source: Ministry of Land, Infrastructure, Transport and Tourism, 2021 Road Traffic Census: General Traffic Volume Survey (令和3年度 全国道路・街路交通情勢調査 一般交通量調査)
- Comparison source: Ministry of Land, Infrastructure, Transport and Tourism, 2015 Road Traffic Census: General Traffic Volume Survey (平成27年度 全国道路・街路交通情勢調査 一般交通量調査)
- Traffic volume is generally the combined weekday 24-hour motor-vehicle traffic volume in both directions.
- Combined values are extended totals calculated by adding the traffic volume of each basic road section. They are not counts of unique vehicles actually driven.
- Only sections whose locations could be verified in official materials are shown on the map.
- Results from the 2025 survey will be added after their official publication. They are not used at present.