On 23 February 2021 the Nikolaifleet canal was opened to shipping after comprehensive remedial maintenance.

The river barrier gates were removed and replaced by new ones, the operations building demolished and replaced by a new build. The entire electrical and hydraulic systems and the control technology have been replaced. After this modernisation and upgrade of the plant, the Nikolai River Barrier is all set to face the coming decades. Overall construction costs are estimated at 11.6 million euros. Storm surge protection was ensured throughout the entire construction period.

Once traffic restrictions along the Kajen / Hohe Brücke / Bei dem Neuen Krahn route had been lifted in late December, the Nikolai River Barrier and the Nikolaifleet Canal were once more opened to shipping. In the future, the river barrier will be operated fully automatically from the control station at the Schaartor Lock.

GRASSL contributed comprehensive design and checking services to the renovation of the 59-year-old river barrier.