What Will Change with the Transition to the Japanese Geodetic System 2024 (JGD2024)? Impact on Construction and Surveying Sites and Measures
Published April 18, 2025
Starting in April 2025, Japan's geodetic system will switch to the "Japanese Geodetic System 2024 (JGD2024)," which may cause confusion or concern for those working on construction, civil engineering, and surveying sites. You might be worried that the coordinates and elevations on your drawings will change drastically, or that the existing surveying data and equipment will no longer be usable.
In reality, terms like "geodetic system change" or "coordinate system transition" might sound technical and complicated. However, once you understand the key points, the transition to JGD2024 is not something to fear; in fact, it is a positive change that will improve accuracy and efficiency on-site.
This article will clearly explain "What JGD2024 is," and "What specifically will change from JGD2011," along with the background of the changes, their impact on the field, and practical measures to ensure a smooth transition.
Table of Contents
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What is JGD2024? Basic Information and Background
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What Will Change from JGD2011?
Horizontal coordinates will remain the same, but elevations will be revised. -
Background of the Geodetic System Change:
The change is driven by the impact of crustal movements, limitations in leveling surveys, and the introduction of a new geoid model. -
Specific Impact and Key Points for the Field
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Practical Measures for the Transition
(Survey Data Conversion, Management, and Product Compatibility) -
Key Points to Remember for the Transition to the Japanese Geodetic System 2024 (JGD2024)
What is JGD2024? Basic Information and Background
JGD2024 (Japanese Geodetic System 2024) is the name of Japan’s latest geodetic reference coordinate system. This new coordinate reference, which will be officially implemented from April 1, 2025, will replace the previously used JGD2011 (Japanese Geodetic System 2011).
The name "2024" refers to the year (Reiwa 6, 2024) when the measurement results were updated, marking the reference year for the new system. In line with this, the Geospatial Information Authority of Japan (GSI) will update the official measurement results for national reference points (such as electronic reference points, triangulation points, and leveling points) to match this date, defining the new geodetic results as "Geodetic Results 2024." As a result, the geodetic system name has been changed from JGD2011 to JGD2024.
The important thing to note is that the basic framework of the Japanese Geodetic System itself—such as the latitude and longitude coordinate system and the ellipsoid—remains unchanged from JGD2011. The transition to JGD2024 is primarily aimed at updating the nationwide elevation (height) values, while definitions of horizontal positions, such as latitude and longitude, remain unchanged. In other words, this geodetic system change is essentially a review of the national height reference, and the name change aligns with the updated survey results for the new year.
Now, let’s take a closer look at what will change and what will remain the same.
What Will Change from JGD2011? Horizontal Coordinates Remain the Same, Only Elevations Will Be Revised
In short, the only aspect affected by the transition from JGD2011 to JGD2024 is the elevation values. The horizontal coordinates, such as latitude, longitude, and the plane rectangular coordinate system, will continue to use the same reference system, so their values will remain unchanged.
For example, the position on the map (X, Y coordinates) or the latitude and longitude information obtained from GPS will be the same in both JGD2011 and JGD2024, so there is no need to worry about sudden discrepancies in the flat positions of the drawings.
On the other hand, elevations (heights) will undergo a nationwide review and revision. The long-standing elevation reference points will be updated with the latest survey data, which will result in elevation differences (height discrepancies) ranging from a few centimeters to several tens of centimeters at various locations. The amount of change in elevation (height difference) will vary by region, with the maximum difference being approximately ±60 cm.
For instance, according to the Geospatial Information Authority of Japan's estimates, in the Ojika Peninsula in Miyagi Prefecture, the revision is about +57 cm, and in the Shiretoko Peninsula in Hokkaido, the revision is about -67 cm (compared to the old elevation). While extreme differences like these are not common, it is expected that the height deviation will be, on average, less than a few tens of centimeters in most regions.
In any case, the basic premise of the JGD2024 transition is "horizontal coordinates remain unchanged, only elevations are revised."
So why is it necessary to revise only the elevations? The background behind this will be explained next.
Background of the Geodetic System Change: Impact of Crustal Movements, Limitations of Leveling Surveys, and the Introduction of a New Geoid Model
The update to Japan’s geodetic system is driven by three main factors: (1) the accumulation of elevation discrepancies due to crustal movements, (2) the limitations in accuracy of traditional methods (leveling surveys), and (3) the advances in satellite positioning technology and geoid models.
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Elevation Discrepancies Due to Crustal Movements:
The Japanese archipelago is constantly moving due to plate tectonics, and particularly in large earthquakes like the Great East Japan Earthquake, the land's height can change significantly in an instant. Traditional reference points (electronic reference points, triangulation points, and leveling points) have maintained the same elevation over the years, leading to discrepancies between the actual surface elevation and the survey reference value. For example, in the Tohoku region, even though the land sank or uplifted after the earthquake, some areas continued to use the old elevation values. -
Cumulative Errors in Leveling Surveys:
Japan's previous height reference system was based on setting the average sea level of Tokyo Bay at 0m, and extending leveling surveys (vertical measurements) from the Japanese leveling benchmark across the country. However, this method accumulated small measurement errors over distance, and the farther from the reference point, the larger the discrepancy from the benchmark. In fact, regions far from the Japanese leveling benchmark, such as Hokkaido and remote islands, accumulated elevation discrepancies of several tens of centimeters relative to the actual average sea level. -
Introduction of Satellite Positioning and the New Geoid Model:
With advancements in technology, satellite positioning systems such as GPS and Quasi-Zenith Satellite System (QZSS) have made it possible to directly measure height. However, the heights obtained from GNSS are based on the ellipsoid (ellipsoidal height) and differ from the traditional "altitude" (elevation). This is where the geoid model comes into play. The geoid represents the gravity potential surface that corresponds to the mean sea level (effectively the "altitude reference surface"). By subtracting the geoid height from the ellipsoidal height, the elevation can be determined.
In this update, the Geospatial Information Authority of Japan (GSI) has developed a more precise new geoid model called Geoid 2024 Japan and its Surroundings, using gravity data. This model provides a reference surface that aligns with the average sea level of Tokyo Bay, ensuring consistency nationwide.
Based on the above background, the Geospatial Information Authority of Japan (GSI) has made the decision to transition to a new elevation system based on "satellite positioning + geoid models." This will resolve the elevation discrepancies caused by long-term crustal movements, allowing for rapid provision of accurate elevation data based on current conditions.
For example, even immediately after a major earthquake, GNSS observations combined with the new geoid model will enable quick recalculation and revision of elevations across regions, allowing recovery and reconstruction efforts to proceed without delay.
Additionally, GNSS-based height measurement (GNSS elevation surveying) has been introduced for public surveying, which is expected to improve efficiency and reduce labor compared to traditional leveling surveys.
In short, the transition to JGD2024 is an essential update to enhance accuracy and improve work efficiency.
Now, let’s take a closer look at how this change will impact actual on-site operations.
Specific Impacts and Key Points for the Field
During the transition to JGD2024, construction and surveying sites need to pay particular attention to discrepancies in elevation data. Below, we outline key points and practical measures that have significant impacts on the field.
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Be Aware of Elevation Discrepancies:
As mentioned earlier, elevation values at reference points will change by several centimeters to tens of centimeters across different regions. For example, a location that was previously marked as "elevation 100.00m" may become "100.30m" under the new standards. When using known reference points for on-site work, it is essential to verify whether the elevation is based on the old standard (JGD2011) or the new standard (JGD2024). If you proceed without recognizing this mix-up, there is a risk of significant rework later, as the survey results may not align. This is especially important immediately after the transition period, as old and new elevation values may be mixed on-site. -
Impact on Drawings and Designs:
It is also crucial to be mindful of the elevation reference used in design drawings and construction plans. For example, in designs where absolute elevation values are critical, such as in the gradient design of water supply and drainage systems or the final height of land development, discrepancies may arise between the design values and the actual site measurements due to the differences in old and new elevations. For projects commissioned by the government or local authorities after April 2025, submission of results based on the new elevation standards will be required. Therefore, even ongoing projects before the transition should consider converting to the new standard and revising designs as necessary. If existing drawings are used as-is, be sure to include notes such as "elevation based on JGD2011" to clarify the elevation reference. Ensuring that all stakeholders share the same understanding will help prevent construction errors due to misunderstandings. -
Surveying Equipment and GNSS Compatibility:
Surveying equipment and GNSS devices will need to be updated. Starting on April 1, 2025, correction information provided by electronic reference points and RTK positioning results using VRS (Virtual Reference Stations) will switch to the new elevation system. Therefore, when performing GNSS measurements across April 1, great care must be taken to ensure that elevation values from before and after the revision do not get mixed. Specifically, GNSS receivers and data controllers will need to be updated to the "Geoid 2024" model settings. Failing to do so will result in calculations based on the old geoid model, causing discrepancies of several tens of centimeters. Additionally, optical levels (auto levels) and total stations measure height differences relative to known heights, but do not forget to replace reference heights and benchmarks on-site with the new standard.
Based on these points, the next chapter will introduce practical measures for the transition to JGD2024.
Practical Measures for the Transition (Survey Data Conversion, Management, and Product Compatibility)
To smoothly transition to JGD2024, let's outline what can be prepared on-site starting now. The three key points are “converting existing data,” “ensuring data management,” and “updating equipment and software.”
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Converting Existing Survey Data:
Consider converting (or transforming) past elevation data and reference point heights to align with the new standard. The Geospatial Information Authority of Japan (GSI) has published “elevation correction parameters (grid data)” to convert old elevation data to the new standard. Using this data, you can apply the appropriate corrections to the old elevation values obtained with the previous geodetic system, adapting them to the new system (JGD2024). For example, when converting between the old and new coordinate systems in software, applying this parameter will automatically correct the elevation values. However, since slight errors may accompany the correction, extra caution is needed in cases where high precision is required. For critical projects, it’s recommended to either resurvey and directly obtain new elevation values after the transition or refer to the officially updated reference point results for peace of mind. -
Ensuring Data Management and Sharing:
Establish a clear system for managing which geodetic system (coordinate system) is used for survey results and design data. During the transition period, data from JGD2011 and JGD2024 will be mixed, so it is advisable to explicitly label files, drawings, and metadata with “JGD2011” or “JGD2024.” For example, include the coordinate system in reference point registers or results tables, and add annotations like “(elevation based on JGD2024)” in drawing legends. It’s a good idea to set a shared format within the company. Centralized management of coordinate systems will reduce the risk of using incorrect data within the team. Additionally, for historical data, it may be helpful to use batch conversion tools to create new data sets based on the updated standard, which will be convenient later on. -
Updating Equipment and Software (Product Compatibility):
Check if your surveying equipment and software are compatible with JGD2024 and perform any necessary updates. Major manufacturers have been releasing firmware updates for surveying equipment and geoid model files in line with this transition. For GNSS receivers and data collectors, it’s necessary to install the new geoid model file “Geoid 2024” on the equipment. LRTK Series and other state-of-the-art RTK-GNSS equipment and surveying software products are progressively being updated to support JGD2024. By updating on-site equipment, you’ll be able to continue surveying and design tasks following the same procedures as before the transition.
If you are unsure how to update your equipment, please contact our support desk. By implementing these measures, you can minimize confusion caused by the transition to JGD2024.
Key Points to Remember for the Transition to the Japanese Geodetic System 2024 (JGD2024)
When transitioning to JGD2024, the key points to keep in mind are:
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Horizontal coordinates remain unchanged
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Only elevations are updated
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Regional differences exist, but elevation changes are typically a maximum of a few tens of centimeters
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New technology enhances precision
While it may seem confusing at first, understanding the system and taking proactive measures will ensure that no significant issues arise on-site. In fact, with JGD2024, the elevation discrepancies that have been unnoticed until now will be reset, allowing for more accurate and consistent survey data handling. This can lead to improvements in construction quality and surveying efficiency in the future.
The anxiety during the transition period often stems from "not knowing" the details. We hope the content of this article has been helpful and will alleviate some of your concerns. If you have questions such as "How should I specifically respond?" or "I'm unsure if my equipment is updated," please feel free to reach out to us for assistance.
We also provide detailed information and solution proposals regarding JGD2024 on our product introduction page. For individual inquiries or to check the compatibility of your equipment, please contact us via the inquiry page, and our expert staff will support you.
Let’s work together to ensure a smooth transition to the latest geodetic system and make your future surveying and construction tasks safer and more reliable. Thank you for reading until the end. We wish you continued safe and accurate operations on-site.
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