Paris's Digital Archive Problem: The Hidden Cost of Duplicate Images Clogging City Systems

Paris municipal and metropolitan agencies are sitting on hundreds of terabytes of duplicated image data, a structural inefficiency that independent auditors have flagged repeatedly but that city administrators have been slow to quantify — let alone fix. The problem is not glamorous, but the numbers attached to it are striking.

Cloud storage costs for French public-sector bodies rose sharply after the passage of the 2021 loi relative à la différenciation, décentralisation, déconcentration et portant diverses mesures de simplification — the so-called loi 3DS — which pushed more planning and housing documentation duties onto regional authorities. Greater Paris, operating across 12 departments, now manages image repositories spread across at least six separate content-management platforms, according to procurement documents published on the BOAMP public-contracts bulletin board. When teams upload the same architectural rendering or housing-stock photograph to multiple systems without a deduplication protocol in place, the redundancy compounds quickly.

The Scale of the Problem in Hard Numbers

Duplication rates in large institutional image libraries routinely run between 20 and 35 percent of total stored assets, according to benchmarks published by the European Commission's Joinup open-source observatory in its 2024 Digital Government Factsheet for France. Apply even the low end of that range to a mid-sized metropolitan authority running several terabytes of planning imagery, and you are looking at hundreds of gigabytes of pure waste — data that costs money to store, back up, and transfer every single month.

For Paris specifically, the Grand Paris Express project — the 200-kilometre automated metro expansion managed by Société du Grand Paris, now rebranded as SNCF Réseau's Grand Paris subsidiary — has generated an enormous visual archive since construction began in earnest around 2019. Progress photos, environmental-impact scans, and BIM (Building Information Modelling) renderings for stations including Saint-Denis Pleyel, Bagneux, and Champigny Centre are stored across contractor intranets, Société du Grand Paris's own document-management system, and the Île-de-France Mobilités coordination portal. Duplicate images across those three systems alone represent a real and measurable storage liability.

The Paris urban-regeneration agency Apur — the Atelier Parisien d'Urbanisme, headquartered on Boulevard Morland in the 4th arrondissement — published a data-governance review in late 2024 that noted image asset duplication as one of three primary causes of ballooning storage costs across Paris City Hall's linked digital infrastructure. Apur does not publish specific cost figures in that review, but the document describes the issue as a priority for remediation before the next municipal budget cycle.

Why 2026 Is the Forcing Function

Two converging pressures are making this a live budget issue right now, in the summer of 2026. First, the Paris 2024 Olympics legacy programme — administered through the Délégation interministérielle aux Jeux Olympiques et Paralympiques — created a large secondary image archive documenting post-Games venue transformations at sites including the Stade de France footprint in Saint-Denis and the Aquatics Centre in Saint-Denis-Pleyel. That archive was never formally deduplicated after the Games concluded in August 2024. Second, Seine urban regeneration work, centred on the Quai d'Austerlitz corridor and stretching toward the Bercy-Charenton development zone in the 12th arrondissement, is generating fresh photographic documentation monthly.

Storage is not free. Commercial cloud pricing for public-sector contracts in France typically runs between €18 and €35 per terabyte per month depending on redundancy tier, based on published rate cards from providers operating under the SecNumCloud framework overseen by ANSSI, the national cybersecurity agency. At those rates, even 10 terabytes of genuinely redundant image data costs a public body between €2,160 and €4,200 per year — and metropolitan Paris is not managing 10 terabytes. It is managing orders of magnitude more.

Practical remediation is straightforward in principle. Deduplication software using perceptual hashing — tools that identify visually identical or near-identical images even when file names differ — can reduce redundancy rates to under 5 percent in a single sweep. Several open-source solutions certified under the French government's SILL (Socle Interministériel de Logiciels Libres) catalogue are available at no licence cost. The harder task is governance: agreeing which agency holds the master copy, and enforcing upload protocols across dozens of contractors and sub-contractors. For a metropolis mid-way through its most ambitious infrastructure expansion in a generation, that conversation is overdue.