Do you know Japan’s Shikoku region?
Shikoku is an island region consisting of four prefectures: Tokushima, Kagawa, Ehime, and Kochi.
There are roads along the Seto Inland Sea and Pacific sides, roads crossing the center of the island, and roads continuing across the sea toward Honshu.
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 Shikoku’s road traffic volumes through a map and data.
Compare them with road conditions in your own country. What differences can we discover together?
Shikoku Road Traffic Volume Map
First, let us explore Shikoku’s roads on the map.
You can switch between expressway-category roads (expressways and urban expressways in this dataset), general national roads, and prefectural 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 Shikoku. 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, and prefectural 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 5,346 basic road sections across Shikoku’s four prefectures whose representative locations and section lines could be verified using the ministry’s official web map.
These consist of 105 expressway-category sections, 1,558 general national road sections, and 3,683 prefectural road sections. In the official national CSV, no sections in Shikoku’s four prefectures are classified as surveyed city roads.
This is not a map of every local road. Traffic surveys conducted independently by local governments have not been added.
Comparison with 2015
Of the 5,346 basic road sections shown on the map, 5,146 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 Shikoku’s Expressway-Category Roads Change?
Let us compare traffic on Shikoku’s expressway-category roads in 2015 and 2021.
Across the 101 basic road sections that can be compared in both years, the combined traffic volume decreased by 8.2%.
This total is not the number of individual vehicles driven in Shikoku. If the same vehicle passes through several survey sections, it is counted once in each section.
Move the Map from Central Shikoku Across Four Prefectures
In Shikoku, roads run not only along the coast but also through the center of the island.
From there, they continue into Tokushima, Kagawa, Ehime, and Kochi, while some sections connect across the sea toward Honshu.
How does the pattern of circles change when you switch between expressway-category roads, general national roads, and prefectural roads?
Follow Shikoku’s Roads for the First Time
You do not need to know Shikoku’s place names or road names in detail.
When I view the roads along the coast together with those crossing the center of the island, their overall shape reminds me of エ, the Japanese katakana character “e.” What shape do you see?
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 Shikoku.
The map and data may help you discover a road in Shikoku 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.