The large-scale renovation of the Krammer Locks complex is officially underway. This project will future-proof one of the Netherlands’ most vital hydraulic engineering links, ensuring safety, smooth passage and sustainability for decades to come.
First lock gate transported to Vlissingen for modernisation
On Wednesday 15 October 2025, the first major milestone was reached: the reserve lock gate was safely lifted onto a pontoon and transported to Vlissingen for modernisation. In June 2026, this gate will return and replace a gate in the lock chamber, which will then undergo the same overhaul.
Why this renovation?
Built between 1976 and 1987, the Krammer Locks are a crucial link in the international maritime corridor connecting Rotterdam, Antwerp and Ghent. Around 66,000 vessels pass through the complex each year, which also maintains a strict separation between the fresh water of the Volkerak-Zoommeer and the salt water of the Eastern Scheldt. After more than 35 years of service, a comprehensive upgrade is essential to guarantee safety, efficiency and sustainability.
Scope of works
The complex comprises four locks: two for commercial vessels and two for recreational vessels. The gates of the commercial locks are being refurbished one by one in a workshop in Vlissingen, with each overhaul taking about six months.
The impressive push-tow lock gates (26 metres long, 12 metres high and weighing 340 tonnes) are being adapted to a new bubble screen system, which will replace the current method of separating fresh and salt water. This brings two major benefits:
- Faster passage: Vessels will pass through on average 33% faster, in half an hour instead of 45 minutes.
- Energy savings: The new system will reduce energy consumption by 35%, a significant step in lowering the usage of one of Rijkswaterstaat’s largest energy consumers.
In addition to refurbishing the lock gates, all mechanical and electrical installations are being renewed, with around 900 kilometres of cable being replaced. The complex will also be prepared for remote operation from Neeltje Jans. Finally, a new fish passage is foreseen.
BESIX: Expertise in complex infrastructure
Rijkswaterstaat awarded this project to BESIX in May 2024. BESIX leads the works within the ZEEKR consortium, alongside BESIX Unitec Nederland, Croonwolter&dros, Demako, Iemants and Bosch Rexroth. This partnership builds on previous successful projects in the Netherlands, such as the Princess Beatrix Lock and the A16 motorway in Rotterdam.
With decades of experience in marine construction, BESIX is taking the lead in one of the most challenging renovations in the Dutch locks programme. The project also showcases BESIX’s integrated service model: BESIX Unitec Nederland is responsible for all electrical and industrial automation systems, while BE Inject (part of Franki Foundations) is handling concrete repairs.
Timeline and challenges
On-site works at the Krammer Locks will begin in spring 2026 and continue until the end of 2028, followed by three years of maintenance.
The greatest challenge? Carrying out this complex renovation while keeping the locks operational and ensuring the safety of more than 200 people involved in the project.
