Nearly 150,000 cargo ships and 220 billion kilos of goods pass through the Volkerak Locks annually. This lock complex, located on the border of South Holland and North Brabant, is the largest and busiest inland navigation lock complex in Europe. It's no wonder this lock complex serves a significant economic purpose. Commissioned by Vialis, Delta Pi mapped the reliability and availability of the Volkerak Locks using a RA analysis.
Management and maintenance
With three commercial locks for cargo ships, one yacht lock for recreational craft, a movable bridge, an inlet lock, and a central control building, the Volkerak Locks are a large and complex complex of structures. Rijkswaterstaat has commissioned Vialis, a company specializing in infrastructure projects, to manage and maintain these structures under a multi-year maintenance contract.
While it's logical that a major complex like the Volkerak Locks needs to be properly managed and maintained, it's also crucial that Vialis causes minimal disruption to its users through malfunctions or scheduled maintenance. In short, the systems must be sufficiently reliable and available, and Vialis has implemented a variety of measures to achieve this.
Measure and analyze performance
The maintenance and management of Vialis must, of course, ensure that the lock complex functions as smoothly as possible: it must deliver and continue to deliver the desired performance. Given the important functions performed by the Volkerak locks and the high volume of shipping traffic that uses them, Rijkswaterstaat has imposed strict requirements on this performance. For example, the locks must function properly to allow both recreational vessels and cargo ships to sail quickly from A to B. Therefore, the central control system for the lock complex may not be out of service for more than 44 hours per year. A RAMS requirement has also been imposed on the availability of the commercial locks: the locks must be available at least 98.5% of the time. In addition to these requirements, Rijkswaterstaat has many other wishes and requirements regarding the performance of the lock complex described in the Vialis contract.
To verify whether the lock complex—and thus Vialis—meets the required requirements, they can measure and report its performance retrospectively. However, such measurements do not guarantee good future performance. To assess in advance whether the measures taken are sufficient to actually achieve the desired reliability and availability in the future, Vialis commissioned Delta Pi to conduct a RA analysis. Our consultant, Ronny van den Heuvel, taking on this project.
What is an RA analysis?
A RA ) analysis calculates the expected reliability and availability of assets. It also determines which systems are critical to achieving performance. The results of this analysis provide greater insight into expected performance and maintenance requirements. This enables Vialis employees to act promptly and anticipate potential future events. For example, by replacing old systems with reliable new ones or by maintaining sufficient components in stock to reduce repair times.
The conclusion
The objects of the Volkerak Lock complex have many interrelated functionalities. Each of these functionalities has specific performance requirements. Although the assignment is not yet complete, Ronny has prepared and/or updated RA analyses for several objects within the lock complex. For example, he analyzed the availability and reliability of the commercial shipping locks and the central control system. The most important conclusion? The expected (calculated) unavailability does not meet the requirements for the central control system and the commercial shipping locks. This is a striking conclusion, as subsequent practical measurements showed that both objects did meet the requirements.
How can that be?
Ronny's conclusions demonstrate a gap between theory and practice. This gap is caused by several factors. One reason is that the model assumes an average unavailability. This unavailability has not occurred in practice (perhaps the major failures are yet to come?). Another explanation for the difference between theory and practice is that (too) strict failure definitions were used in the calculations (as per the contract) and that the model is quite conservative. A third explanation is that the theoretical failure definitions are not applied in the same way in practice. We would like to explain this last point with an example:
Suppose one of the lock complex's cameras fails. If we follow the theoretical model, that broken camera could cause the central control system to fail. However, in practice, the broken camera might not cause any malfunction at all, and the central control system might continue to function normally.
In short: the failure definitions and requirements are too strict, and theory and practice don't align. This led Ronny to not only conclude that the analyzed objects don't meet the stated requirements, but also advise the client to adjust the failure definitions and requirements (among other things).
Purpose of RA analysis
With the RA analysis, we examine the reliability and availability of the Volkerak Locks. The ultimate goal is to ensure that the systems and equipment continue to meet the desired performance requirements in the future. Delta Pi's RA analysis ensures that Vialis and Rijkswaterstaat are also ready for tomorrow!
Would you also like help with creating or updating a RAMS analysis? Or would you like to gain more knowledge in the field?
