France Completes Seven-Year Project to Remap National Altitude with Unprecedented Precision
France is entering a new era of geographic accuracy following the completion of a seven-year initiative by the National Institute of Geographic and Forest Information (IGN) to precisely map the nation’s altitude. The ambitious project, which concluded this week in Dunkirk, aims to create a more consistent and reliable altitude system, aligning France’s measurements with those of its European neighbors.
For seven years, teams of engineers have traversed the country, meticulously collecting data to update existing geographic information. The effort involved traveling 3,600 kilometers and conducting 1,800 kilometers of high-precision leveling measurements, beginning on the Côte d’Azur and extending along the eastern border with Italy, Switzerland, Germany, Luxembourg, and Belgium.
The project builds upon the IGN’s existing leveling network, which has been observed since 1983. More information on the network can be found here: https://geodesie.ign.fr/le-reseau-niref. But why undertake such a comprehensive and painstaking effort?
“This aims to define a new altitude system, to be more consistent with neighboring countries. The more precision we gain, the better,” explained a senior official from the IGN. The increased accuracy is not merely an academic exercise; it has significant implications for a wide range of practical applications.
According to the IGN, the refined altitude data will be crucial for civil engineering projects, aviation, and various other fields that rely on precise vertical measurements. “This is all the more important with global warming and the environment, altitudes can move,” the official added, highlighting the dynamic nature of the landscape and the need for up-to-date information.
The process itself, while technologically advanced in its overall goal, relies on a surprisingly simple core principle. “To make the leveling of precision, it is quite simple: we take an optical level, we will aim for a point, we aim for another point and we measure the difference, and that is what was done between Nice and Dunkirk,” the official explained. However, the precision demanded by the project necessitates a slow and deliberate pace – approximately thirty meters of measurement at a time.
The project’s baseline is rooted in France’s historical geographic reference point: the Marseille tide, the oldest in the country, which has defined altitude zero since the 19th century. Engineers began their measurements in Nice, referencing altitudes across the territory in relation to this established benchmark. The team navigated challenging terrain, including the Alps and the iconic Col de la Bonnette, to establish a network of interconnected, precisely calculated altitudes.
The ultimate goal, as emphasized by the IGN, is to create a more reliable and consistent system for measuring altitude, not just within France, but in relation to its European partners. “There, it is really a question of having a new more reliable system, this one will be more precise, we improve our knowledge, it will be more consistent with the system of our neighbors,” the official concluded. This commitment to precision underscores France’s dedication to maintaining a modern and accurate geographic infrastructure for the benefit of its citizens and industries.
