Eiffage Énergie Systèmes to replace 342 light fixtures in four weeks on an A14 overpass, on behalf of SAPN

The A14 viaduct, built in the 1990s, is a civil engineering structure protected by the architects’ copyright. Consequently, any change to the aesthetic appearance of the lighting - integrated into the very structure of the guardrails – must be specifically requested. To work around these stringent requirements, our experts have designed a customised solution for SAPN that requires no specific alterations to the structure: stainless steel plates (manufactured in-house by a supplier), featuring a narrow opening to accommodate new LED light fittings that are more powerful and more compact than the existing models. A prototype was built and approved before production of the 342 units began. “We won the contract by sticking to a tight schedule and optimising our approach,” explained project manager Émeric Dybele.

Sixteen nights to replace everything

The motorway closures, each costing the operator €5,000 per night, have been scheduled a year in advance, with no scope for any overrun. The works are divided into two 2-week phases starting on 21 September and will take place exclusively at night (between 10.00 pm and 4.00 am), over a total of 16 nights. Our staff, equipped with five aerial work platforms and several lorries, will be working simultaneously on the viaduct, at a height of 4 metres. “We face a double challenge on this project! We have to work quickly, maintaining functional lighting on one carriageway at all times while work is being carried out on the other. In other words, we absolutely must complete one entire carriageway and bring it into service before we can start removing the light fixtures on the next one,” continued Émeric Dybele.

Crucial preparatory work

Most of the assembly work (light fittings, drivers and mounting plates) is carried out in the workshop prior to the project, to ensure we meet the deadlines. On site, our experts must then remove the old systems, run the cables through the ducts and connect the new pre-assembled kits. The power supply will be completely re-wired. “It’s a real challenge, because we weren’t necessarily expected to tackle this sort of project. But if the work goes to plan, our experience could well prove valuable for the future,” said Émeric Dybele. Especially since the prospects for standardising the lighting are very real, given that the A14, in the immediate vicinity of La Défense, runs along a second viaduct fitted with the same lighting system. Building on the experience gained — validated prototype, tried-and-tested methodology, successful planning — our specialists will be ideally placed to demonstrate their expertise on a similar project.