Instrumentation of the Eiffel Tower for Continuous Monitoring

The Eiffel Tower stands as a historic and iconic monument in the city of Paris. With a total height of 330 meters and constructed with wrought iron, it features a lattice metal structure. Completed in 1889 after two years of construction, the tower was initially designed for a 20-year lifespan. Now over 130 years old and welcoming millions of visitors annually, it has become a compelling example of extending the lifespan of a structure through vigilant surveillance and maintenance. Historically, the Eiffel Tower's surveillance program primarily consisted of repeated comprehensive and detailed inspections. Since 2021, it has been equipped with sensors to continuously monitor its overall behaviour. This instrumentation includes motoring of the spire’s inclination, as well as monitoring displacements, deformations, and vibrations in its four pillars. Temperature and humidity measurements are also acquired across the structure, to help providing a comprehensive analysis. This paper presents the implemented instrumentation, addressing challenges related to its deployment, and proposes a first analysis two years after the beginning of the campaign. Seasonal movements and trends are identified, and a brief dynamic study is conducted. Finally, the paper discusses the approach of instrumentation for exceptional structures to complete ongoing surveillance.