Princess Marijke lock: renovate with the store open

Rijkswaterstaat and Mourik Infra are renovating the Princess Marijke Lock while shipping in the Amsterdam-Rhine Canal continues and the flood barrier remains in operation. The planning follows water safety: working during the low-water season and being able to close when the water level rises. "It's renovation with the store open," says René Diks, contract manager at Rijkswaterstaat.

The renovation is being carried out under a two-phase contract. Phase 1 (March 2022-November 2023) focused on research, design and risk management; phase 2 (from Jan. 1, 2024) is realization. The final milestone is scheduled for March 2027. "We made a robust schedule," says Sake Hemstra, project manager and contract manager at Mourik Infra. "Some work simply does not tolerate high water and that determines the rhythm."

At the heart of the collaboration is a thorough risk file. In Phase 1, about 40 studies were conducted to reduce uncertainties (including the condition of the lock gates underwater). The remaining 40-50 quantified risks were assigned to the contractor or client, with a reserved budget. Diks: "That way you avoid unnecessary risk mark-ups in the price, and you keep room to solve unexpected situations professionally, without coming up against each other." Hemstra: "It takes the pressure off the project and works very pleasantly."

Safety dictates planning

The lock also has the function of a primary flood barrier. Work on the flood barrier may only be tackled during the low-water season. At the same time, when high water approaches, the retaining slide (80-meter-wide water retaining movable slide) and the lock must be able to close completely within three days. "Among other things, we monitor the water levels at Lobith," says Diks. "If a wave announces itself, the auxiliary structure of the retaining slide has to come off and the complex has to close. That's a hard requirement." Hemstra calls it one of the most exciting aspects of the work: protocols are in place to complete the work in an accelerated and safe manner. To date, it has not yet happened that the auxiliary structure to the flood barrier had to be demolished due to high water.

An additional challenge is the retaining slide across the Amsterdam-Rijnkanaal: conservation must take place above water and cannot be accomplished in one low-water season. "That is why we divide the floodgate and the gullies over two years: this year one half and one gully, next year the other half and the other gully," Hemstra said.

Drying 

Rijkswaterstaat and Mourik chose to put the lock sections and heads dry instead of working with culverts in wet conditions. Diks: "Working dry reduces safety risks and makes quality control demonstrably better." Hemstra: "This requires substantial temporary facilities, but you can get to it, you can see what you are doing and you can properly assess the operation." For drying, Mourik produced heavy drying bulkheads (about 40 tons each) in its own steel plant. "The fact that we make many critical components ourselves ensures speed and grip. The client then talks directly with the makers," said Hemstra.

Work above the waterway also imposes environmental requirements. During blasting and coating above the canal, strict measures apply to prevent emissions to the water. "In this we cooperate intensively, with careful work plans and supervision," says Diks.

Milestone

This year's focus is on major maintenance on the east chamber and preserving the first half of the floodgate. "We aim to have the new east chamber up and running in November, with renovated control boxes, equipment, lock gates and drives," Hemstra says. "That will be an important milestone. The work has a repetitive nature, so success this year gives confidence for next year." In parallel, the team is working to carefully assemble and dismantle the auxiliary structure at the floodgate: "It should be able to be completely dismantled as soon as the flood season begins."

The project features impressive lifting work. Hemstra: "Floating trestles, lock gates and drywells - it's beautiful work. You see almost the entire civilian spectrum coming together here."

Learning in the 'lock yard'

The Princess Marijke Lock is one of the first projects in Rijkswaterstaat's so-called 'lock yard': this brings together several lock teams to tackle the renewal of Rijkswaterstaat's lock network. Projects are combined in portfolios and lock teams develop with and learn from each other. Experiences are shared, reused and scaled up. "Nationwide, there are 86 lock complexes in the program," says Diks. "We want to learn from projects like this and thus offer a recognizable, attractive work package for the market, with continuity and synergy benefits." According to Hemstra, you see that teams get used to each other faster, especially if starting points are clear at the front. "Give each other a few months in preparation to get to know each other better and to anchor processes, tools and working methods. That pays off handsomely."

An important lesson for future projects: work out the starting points and requirements a little further in advance, without stifling innovation. Diks: "If you start with a minimal framework of requirements, it takes a lot of time to figure out together 'what exactly do we want?' That can be done better." Hemstra: "With a more solid foundation, you can move faster to design and implementation."

Cooperation in the chain

Mourik works with a trusted team of partners that has also proved a successful formula in previous lock renovations. "We choose the same proven partners whenever possible; you know what you have on each other," says Hemstra. "And as a family business with its own steel company, we can engineer and produce crucial components ourselves." Diks: "You notice that. A general contractor with regular partners who know each other acts as one team. That benefits predictability and quality."