1001 Smart Cities

Permanent project revision

Maeslant Barrier: Software Gives the Order to Close Rotterdam to the Sea

Revision 2026-11-06-landmark-p6-uplift · effective 2026-11-06

Superseded. A later revision exists: 2026-11-06-deltares-enw-additions →

unreviewed

Landmark of the Week: record rebuilt from 22 primary sources. Corrected the closure count (Rijkswaterstaat now counts one storm closure, 21 December 2023; 2007 and 2018 ran at a lowered test level), removed the claim that an independent team verified the control software (two of five authors work for Rijkswaterstaat), added the 2026 ICT review board findings on BESW, outcome succeeded -> ongoing under the success-needs-evidence rule, full claim array including 67 story claims.

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All revisions → Current entity page →

Change set

  • replace /snapshot/projectFingerprint — Updated projectFingerprint to the current sourced project record.
  • replace /snapshot/asOf — Updated asOf to the current sourced project record.
  • replace /snapshot/projectState — Updated projectState to the current sourced project record.
  • replace /snapshot/governance — Updated governance to the current sourced project record.
  • replace /snapshot/claims — Updated claims to the current sourced project record.
  • replace /snapshot/sources — Updated sources to the current sourced project record.
84
of 84 claims mapped
22
source dossiers
16
publication dates recorded
0
archives linked
0
exact locators
0
content captures hashed

Claims, one by one

The text below is copied verbatim from the published record. Each claim names the source dossiers that carry it; caveats stay attached to the claim they qualify.

Claim 1 clm-76deae4754d7f3f2 quantitative
Two steel doors, each 210 metres wide, lie in dry docks on the banks of the Nieuwe Waterweg at Hoek van Holland
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat: the barrier lies in the Nieuwe Waterweg at Hoek van Holland and has two doors 210 m wide, 22 m high and 15 m deep.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Deltawerk Maeslantkering
Claim 2 clm-d47a6969d47997b2 quantitative
a forecasting system called BOS decides to close when the predicted level threatens to reach 3 metres above NAP at Rotterdam or 2.90 metres at Dordrecht
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026: if the predicted water level threatens to reach 3 m above NAP at Rotterdam or 2.90 m at Dordrecht, BOS decides to close the barrier.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 3 clm-abae159afa4221ac descriptive
because the designers' failure analysis concluded that manual control would undermine the barrier's reliability
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The developers' account of why the decision was automated.
Caveat
Written by the developers of the system, about their own work.

Sources carrying this claim

  1. Tretmans, Wijbrans and Chaudron — Software Engineering with Formal Methods: The Development of a Storm Surge Barrier Control System (author preprint, 7 July 2000)
Claim 4 clm-840c4d911ea4d635 descriptive
A team of Rijkswaterstaat experts stands by and can intervene.
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat: when high water is expected, a team of experts is always present to watch the automatic process and intervene if necessary.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Deltawerk Maeslantkering
Claim 5 clm-b0fab00436b966c9 quantitative
A second system, BESW, carries out BOS's commands; it was replaced in 2012, and in August 2026 the government's ICT review board called its state unacceptable for a safety-critical structure.
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026: on BOS's command BESW controls the barrier; its state has been unacceptable since the replacement of hardware and software in 2012.
Caveat
Rijkswaterstaat disputes parts of this assessment and says the barrier meets its legal requirement.

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 6 clm-0b1c7c2b69a03fbb quantitative
Rijkswaterstaat counts one closure against a real storm since the barrier was built: 21 December 2023
Published field
impact · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat's memo of September 2026 and the ICT review board's advice of August 2026 both count one storm closure, in December 2023.
Caveat
In 2007 Rijkswaterstaat's own storm surge report described the November 2007 closure as the first during a storm surge.

Sources carrying this claim

  1. Rijkswaterstaat — memo to the minister on the ICT review board's BESW advice (15 September 2026)
  2. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 9 clm-ce75c13bcccf7fe6 quantitative
Storm closures in 2007 and 2018 ran at a closing level lowered to 2.60 m to test the systems
Published field
impact · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat's live blog (December 2023) on the temporarily lowered level; Hart van Nederland (January 2018) gives 2.60 m for both 2007 and 2018.
Caveat
DutchNews, quoting a spokesman in 2023, gives 2.65 m for the lowered level.

Sources carrying this claim

  1. Rijkswaterstaat — Look back at high water and storm Pia (21 December 2023)
  2. Hart van Nederland — Primeur: alle vijf waterkeringen dicht (3 January 2018)
Claim 10 clm-b7d6ae96ec094e4c quantitative
every September the barrier makes a test closure, the 28th in 2025
Published field
impact · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat: a test closure every September; its 2025 news item reports the 28th.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Deltawerk Maeslantkering
  2. Rijkswaterstaat — Maeslantkering open again after the 28th test closure (14 September 2025)
Claim 11 clm-771994a647e7dc96 quantitative
a 2006 study found both Europoort barriers failing a requirement of at most one failure in a thousand closures
Published field
impact · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat's 2006 hinterland study: both movable parts of the Europoortkering failed their technical reliability requirement, at most one failure to close per thousand closures.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat Zuid-Holland — Achterlandstudie Maeslantkering, main report (15 October 2006)
Claim 12 clm-631b9fdadd497c2f quantitative
the legal requirement today is one failure in 100
Published field
impact · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026.
Caveat
None of the documents read for this entry records when the requirement changed from 1 in 1,000 to 1 in 100.

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 13 clm-2b2f6aae6b607ebf quantitative
In August 2026 the ICT review board counted almost 100 known defects in BESW, at least four manual interventions in 17 closures and three failed repair projects since 2012.
Published field
impact · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026: almost 100 known defects; at least four manual interventions in 17 closures; three repair projects after 2012, all failed.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 15 clm-e200e3aaadba25bf quantitative
The decision layer, built with formal methods thirty years ago, is not where the 2026 review found the trouble; the execution layer replaced in 2012 is.
Published field
lesson · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026: formal methods were used thirty years ago to develop BOS; its findings concern BESW, whose state it calls unacceptable since the 2012 replacement.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 16 clm-19fbffc5b628f032 quantitative
Rijkswaterstaat aims to replace it before the 2030 storm season and calls the chance of missing that date real
Published field
lesson · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board: the project aims to replace BESW before the start of the 2030 storm season; Rijkswaterstaat's memo calls the chance of not succeeding real.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
  2. Rijkswaterstaat — memo to the minister on the ICT review board's BESW advice (15 September 2026)
Claim 17 clm-645e58f896e3591c descriptive
a human team, which has had to step in, stays on duty
Published field
lesson · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat: an expert team is always present at expected high water; ICT review board: at least four manual interventions in 17 closures.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Deltawerk Maeslantkering
  2. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 18 clm-fc1b0b0abb06fa59 quantitative
The barrier was being closed from 20:15 and was shut around 22:00
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
NOS: the barrier was being closed from 20:15 and was shut around 22:00.
Caveat
Rijkswaterstaat's own interview gives 22:15 as the moment the barrier shut.

Sources carrying this claim

  1. NOS — Maeslantkering automatisch gesloten, eerste keer door hoogwater (21 December 2023)
Claim 19 clm-336e4551bf47a74f quantitative
For the first time, the barrier's own criterion, an expected water level of 3.00 m at Rotterdam, had been reached
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat's live blog on 21 December 2023: today is the first time the barrier's criterion, an expected water level of 3.00 m at Rotterdam, has been reached.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Look back at high water and storm Pia (21 December 2023)
Claim 20 clm-6ef16a0e85d3f2ae descriptive
All six of Rijkswaterstaat's storm surge barriers closed that night, the Maeslant barrier automatically for the first time
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat: all six of its storm surge barriers closed, the Maeslant barrier automatically for the first time.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Look back at high water and storm Pia (21 December 2023)
Claim 21 clm-9de89c8ff72cfd51 quantitative
The Maeslant and Hartel barriers reopened at 04:45 the next morning
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat's live blog lists the reopening of the Maeslant and Hartel barriers (Europoortkering) at 04:45 on 22 December 2023.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Look back at high water and storm Pia (21 December 2023)
Claim 22 clm-55be3628dfa35d89 descriptive
The Maeslant barrier was not part of the original Delta Plan
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The Watersnoodmuseum states that the barrier was not part of the original Delta Plan.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Watersnoodmuseum — Maeslant Storm Surge Barrier
Claim 23 clm-b147061792b9a96c descriptive
Unlike the other Delta Works, it was not built by Rijkswaterstaat; a design competition was held, and the Bouwkombinatie Maeslantkering won it
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Watersnoodmuseum: unlike the other Delta Works, the barrier was not constructed by Rijkswaterstaat; a competition was held for the best design, won by the Bouwkombinatie Maeslantkering.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Watersnoodmuseum — Maeslant Storm Surge Barrier
Claim 24 clm-a195d00053807247 quantitative
Construction began in 1991, and six years later Queen Beatrix officially commissioned the barrier
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Watersnoodmuseum: construction began in 1991, and six years later Queen Beatrix officially commissioned the barrier.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Watersnoodmuseum — Maeslant Storm Surge Barrier
Claim 25 clm-f238d5bfb7ad5913 quantitative
Each of its two doors is 210 metres wide and 22 metres high
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat: the barrier has two doors 210 m wide, 22 m high and 15 m deep.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Deltawerk Maeslantkering
Claim 26 clm-283593ba8d5cd919 descriptive
Rijkswaterstaat says no water barrier in the world has larger moving parts
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat's own description of the barrier; no independent comparison is cited.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Deltawerk Maeslantkering
Claim 27 clm-df00cf589404171c quantitative
The barrier had to close at 3 metres above sea level, but no more than once or twice every ten years
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Watersnoodmuseum, on the design brief for the competition.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Watersnoodmuseum — Maeslant Storm Surge Barrier
Claim 28 clm-74058323ae3ebb06 descriptive
an unnecessary closure costs millions of guilders in restricted shipping, while a closed barrier can also flood the city through the Rhine if its water cannot flow out to sea
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The developers' account of the trade-off the control system has to weigh.
Caveat
Written by the developers of the system, about their own work.

Sources carrying this claim

  1. Tretmans, Wijbrans and Chaudron — Software Engineering with Formal Methods: The Development of a Storm Surge Barrier Control System (author preprint, 7 July 2000)
Claim 29 clm-2f0a13ec257ae3b0 descriptive
a careful failure analysis concluded that manual control would undermine that reliability
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The developers report that a failure analysis showed manual control would undermine the required reliability.
Caveat
Written by the developers of the system, about their own work.

Sources carrying this claim

  1. Tretmans, Wijbrans and Chaudron — Software Engineering with Formal Methods: The Development of a Storm Surge Barrier Control System (author preprint, 7 July 2000)
Claim 30 clm-a1544d8ec7759d97 quantitative
a normal human being has a failure probability of one in a thousand for a complex task like deciding when to close the barrier and then closing it
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The figure the developers give for human reliability; the paper states it as a general rule, not as a measurement of the barrier's operators.
Caveat
Written by the developers of the system, about their own work.

Sources carrying this claim

  1. Tretmans, Wijbrans and Chaudron — Software Engineering with Formal Methods: The Development of a Storm Surge Barrier Control System (author preprint, 7 July 2000)
Claim 31 clm-750f8ef0efaa19cd quantitative
Failing to close when needed was to be less likely than one in ten thousand, and failing to open when asked less likely than one in a hundred thousand
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The software requirement in the developers' papers: failure probability below 10^-4 for not closing when necessary and below 10^-5 for not opening when requested.
Caveat
A 2022 paper gives a single figure of 10^-5 for both. Neither is the legal requirement for the whole barrier, which is one failure in 100 closures.

Sources carrying this claim

  1. Tretmans, Wijbrans and Chaudron — Software Engineering with Formal Methods: The Development of a Storm Surge Barrier Control System (author preprint, 7 July 2000)
  2. Chaudron, Tretmans and Wijbrans — Lessons from the Application of Formal Methods to the Design of a Storm Surge Barrier Control System (FM'99, 1999)
Claim 32 clm-78e84ee84a4d90f5 quantitative
BOS was classified at the highest Safety Integrity Level under IEC 61508
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The developers classify BOS at the highest Safety Integrity Level under IEC 61508.
Caveat
Written by the developers of the system, about their own work.

Sources carrying this claim

  1. Tretmans, Wijbrans and Chaudron — Software Engineering with Formal Methods: The Development of a Storm Surge Barrier Control System (author preprint, 7 July 2000)
Claim 33 clm-dc2655d204b906a6 descriptive
was developed by CMG Den Haag, commissioned by Rijkswaterstaat
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The developers' paper names CMG Den Haag as developer and Rijkswaterstaat as client.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Tretmans, Wijbrans and Chaudron — Software Engineering with Formal Methods: The Development of a Storm Surge Barrier Control System (author preprint, 7 July 2000)
Claim 34 clm-6144f1c8a77392af descriptive
the hydrological knowledge and model-based water-level predictions supplied by the Waterloopkundig Laboratorium
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
FM'99 paper on the division of work in the BOS project.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Chaudron, Tretmans and Wijbrans — Lessons from the Application of Formal Methods to the Design of a Storm Surge Barrier Control System (FM'99, 1999)
Claim 35 clm-2c1f9c4eac0f6c90 descriptive
weather forecasts, water-level measurements and the results of flood simulations
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The 2022 paper describes BOS as deciding on the basis of weather forecasts, water-level measurements and flood-simulation results.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Goorden, van de Mortel-Fronczak, van Eldik, Fokkink and Rooda — Lessons learned in the application of formal methods to the design of a storm surge barrier control system (IFAC-PapersOnLine 55, 2022)
Claim 36 clm-471bbd1a9c9995bb quantitative
the computer makes a calculation for the coming 24 hours every ten minutes
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Computable, reporting a 2010 visit to the barrier: every ten minutes the computer makes a calculation for the coming 24 hours.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Computable — ICT is onmisbaar bij waterbeheer (27 May 2010)
Claim 37 clm-c9f4876a24c96d11 quantitative
Development took three years and about 25 person-years, producing 20,000 lines of formal specification and 450,000 lines of C++
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
FM'99: development took three years and about 25 man-years, resulting in 20,000 lines of formal specification and 450,000 lines of (a safe subset of) C++.
Caveat
These figures describe BOS as delivered in 1998, not the control software that runs today.

Sources carrying this claim

  1. Chaudron, Tretmans and Wijbrans — Lessons from the Application of Formal Methods to the Design of a Storm Surge Barrier Control System (FM'99, 1999)
Claim 38 clm-28513f5d8e0d296c quantitative
200,000 lines formed the operational system and 250,000 the simulators, test systems and supporting software
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The journal preprint splits the code into 200 kLOC for the operational system and 250 kLOC for simulators, test systems and supporting software.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Tretmans, Wijbrans and Chaudron — Software Engineering with Formal Methods: The Development of a Storm Surge Barrier Control System (author preprint, 7 July 2000)
Claim 39 clm-a3024c689b4f4b0e descriptive
Model checking with Promela and Spin found significant errors and omissions in early designs
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
FM'99: model checking with Promela and Spin identified significant errors and omissions in early designs.
Caveat
Written by the developers of the system, about their own work.

Sources carrying this claim

  1. Chaudron, Tretmans and Wijbrans — Lessons from the Application of Formal Methods to the Design of a Storm Surge Barrier Control System (FM'99, 1999)
Claim 40 clm-5692e71641c0c4cc descriptive
not a single line of program code was completely proved correct
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The developers state the limit of their formal methods explicitly.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Chaudron, Tretmans and Wijbrans — Lessons from the Application of Formal Methods to the Design of a Storm Surge Barrier Control System (FM'99, 1999)
Claim 41 clm-eeeb348dcabdb5d7 quantitative
BOS was completed in October 1998, on time and within budget
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The developers date BOS's completion to October 1998.
Caveat
Written by the developers of the system, about their own work.

Sources carrying this claim

  1. Tretmans, Wijbrans and Chaudron — Software Engineering with Formal Methods: The Development of a Storm Surge Barrier Control System (author preprint, 7 July 2000)
Claim 42 clm-f650b3617bf9892b descriptive
On BOS's command, a second system called BESW operates the barrier
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board: on BOS's command, BESW (Bedienings- en Besturingssysteem Waterweg) controls the barrier.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 43 clm-0502b6d13dd51b3a descriptive
the closure starts by flooding the dry docks in which the walls lie, so that they float
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board: the closing process starts with flooding the parking docks in which the walls lie, so that they float.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 44 clm-9e148957dd8d3684 quantitative
At the 2025 test, sailing out, closing and sinking the arms took just over two hours
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat on the 13 September 2025 test closure.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Maeslantkering open again after the 28th test closure (14 September 2025)
Claim 45 clm-760a18dd9b75cf2a descriptive
just dropping the structure into the river would send big waves into Rotterdam
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
DutchNews quoting the operations spokesman on why the structure is sunk slowly.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. DutchNews — Rotterdam's massive storm surge barrier passes its annual test (17 September 2023)
Claim 46 clm-dde102264e63a9ab descriptive
Rijkswaterstaat's storm surge warning service reported that the Hartel and Maeslant barriers had closed during a storm surge for the first time
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The 2007 storm surge report lists the barriers closed on 8–9 November 2007 and says the Hartel and Maeslant barriers were closed during a storm surge for the first time.
Caveat
Rijkswaterstaat has since described this closure as a test at a lowered closing level.

Sources carrying this claim

  1. Rijkswaterstaat storm surge warning service — Stormvloedflits 2007-09, 8 and 9 November 2007
Claim 47 clm-99dde53f52453dbd quantitative
the closure on the evening of 8 November was the work of a computer
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
H2O, the water-sector magazine, describing the first closure.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. H2O — Eerste daadwerkelijke sluiting Maeslantkering goed verlopen (2007)
Claim 48 clm-71fb707638d87046 quantitative
On 3 January 2018 the barrier closed again, for a test, and would normally not have closed because the water was not high enough
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
NOS on 3 January 2018: the barrier closed because of a test and would normally not have closed because the water level was not high enough.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. NOS — Westerstorm over hoogtepunt heen (3 January 2018)
Claim 49 clm-469424379792f82c quantitative
as in 2007, the closing level had been lowered to 2.60 metres above NAP
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Hart van Nederland (ANP) on 3 January 2018: in 2007 too the closing level had been lowered to 2.60 m above NAP.
Caveat
DutchNews, quoting a spokesman in 2023, gives 2.65 m for the lowered level.

Sources carrying this claim

  1. Hart van Nederland — Primeur: alle vijf waterkeringen dicht (3 January 2018)
Claim 50 clm-44dd132aecd54fdb quantitative
a water level of 3 metres above NAP had never occurred at Rotterdam during a storm
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
A Rijkswaterstaat spokesperson quoted by Hart van Nederland in January 2018.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Hart van Nederland — Primeur: alle vijf waterkeringen dicht (3 January 2018)
Claim 51 clm-9e03d7280c0c49e8 quantitative
Storms in 2002, 2013 and 2014 nearly closed it, but the official closing level was just not reached
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
NOS in January 2018 on the near-closures.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. NOS — Westerstorm over hoogtepunt heen (3 January 2018)
Claim 52 clm-52ea7ed2ef49316c quantitative
In 2007 and 2018 the barrier also closed during storms, but under a temporarily lowered closing level in order to test the systems
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat's live blog on 21 December 2023.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Look back at high water and storm Pia (21 December 2023)
Claim 53 clm-f53bc68dba304b75 quantitative
since it was built, the barrier has closed because of a storm only once, in December 2023
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat's memo of September 2026; the ICT review board's advice of August 2026 gives the same count.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — memo to the minister on the ICT review board's BESW advice (15 September 2026)
  2. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 54 clm-cd2909767cecc3d0 quantitative
If seven years pass without a storm closure, Rijkswaterstaat lowers the official closing level once to 2.6 m at Rotterdam, instead of 3 m, to test the barrier for real
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat describes this verification closure on its barrier page.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Deltawerk Maeslantkering
Claim 55 clm-7c38f5e87350349c descriptive
every September the Hartel and Maeslant barriers make a test closure
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat: every year in September the Hartel and Maeslant barriers make a test closure.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Deltawerk Maeslantkering
Claim 57 clm-9a37ae509cf8b447 quantitative
In a 2006 study Rijkswaterstaat found that both the Maeslant and Hartel barriers failed their technical reliability requirement
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat's 2006 hinterland study on the second statutory assessment round.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat Zuid-Holland — Achterlandstudie Maeslantkering, main report (15 October 2006)
Claim 58 clm-cedb95055247f567 quantitative
the barriers fail to close when they should at most once in a thousand closures
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The 2006 study explains the then requirement of a closing probability of at least 99.9%.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat Zuid-Holland — Achterlandstudie Maeslantkering, main report (15 October 2006)
Claim 59 clm-5f2f2c7cd6230a00 quantitative
the probability of not closing at up to 1 in 100 per closure demand
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The 2006 study on the latest failure analysis for the 2006–2007 storm season.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat Zuid-Holland — Achterlandstudie Maeslantkering, main report (15 October 2006)
Claim 60 clm-abebcaf9c82a1cd1 descriptive
a realistic and achievable value
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The 2006 study reports that an external review judged 1 in 100 per closure demand a realistic and achievable value.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat Zuid-Holland — Achterlandstudie Maeslantkering, main report (15 October 2006)
Claim 61 clm-340f2e7532c0c21e quantitative
Today the legal requirement is a failure probability on closing of 1 in 100
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 62 clm-1e3d9e838062584a quantitative
after the renovation, which started in 2009 and was delivered in 2012, it turned out in 2014 that its reliability could not be sufficiently demonstrated
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Minister's letter of August 2019: after the renovation of the original ICT control system (started 2009, delivered 2012) it turned out in 2014 that its reliability could not be sufficiently demonstrated.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Minister of Infrastructure and Water Management — letter to parliament on replacing the barrier's control system, Kamerstuk 35 000 J, nr. 34 (15 August 2019)
Claim 63 clm-6c31d596a4487985 quantitative
the barrier would have a control system of demonstrable reliability before the 2021/2022 storm season at the latest
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Minister's letter of August 2019 on the restarted redesign.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Minister of Infrastructure and Water Management — letter to parliament on replacing the barrier's control system, Kamerstuk 35 000 J, nr. 34 (15 August 2019)
Claim 64 clm-6900b6720c6185c4 quantitative
mistakes were made and things were left undone in the 2012 replacement of BESW, which significantly raised the failure probability
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026, on the 2012 replacement of BESW hardware and software.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 65 clm-fb293284d13f0fcd quantitative
the software contains almost 100 known defects that can lead to serious failure
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 66 clm-95632840db5f111c quantitative
three projects after 2012 to repair the faults and omissions in BESW all failed
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 67 clm-1d9842771c6b174c descriptive
BESW fails much more often in reality than Rijkswaterstaat's models predict
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026, on Rijkswaterstaat's fault-tree models.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 68 clm-4e2a04e7e5c04743 descriptive
the current state is unacceptable as the control of a safety-critical object like the Maeslant barrier
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026.
Caveat
Rijkswaterstaat disputes parts of this assessment and says the barrier meets its legal requirement.

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 69 clm-5c90897f1258422f descriptive
formal methods were already used thirty years ago to develop BOS, the system that commands BESW
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 73 clm-657c5390d6577f68 descriptive
When high water is expected, a team of Rijkswaterstaat experts is always present to watch the automatic process and intervene if necessary
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat on its barrier page.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — Deltawerk Maeslantkering
Claim 74 clm-a39f1cb9f20831bf descriptive
it happens automatically, but if needed the team can switch to manual operation
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
A Rijkswaterstaat technical specialist interviewed by H2O in 2007.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. H2O — Eerste daadwerkelijke sluiting Maeslantkering goed verlopen (2007)
Claim 75 clm-bd5fb1b80017a5f8 descriptive
In an emergency the barrier can be operated locally without BOS or BESW
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 76 clm-8efdea47983879ae quantitative
in 17 closures there was manual intervention in the control system at least four times
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026; the advice does not list which closures were affected.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 77 clm-d83a45c18a9dfd04 quantitative
the annual September test closures had each been carried out successfully, including a planned manual closure in 2016
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Minister's letter of August 2019.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Minister of Infrastructure and Water Management — letter to parliament on replacing the barrier's control system, Kamerstuk 35 000 J, nr. 34 (15 August 2019)
Claim 78 clm-301c8196584ea21a quantitative
The new BESW is to last until at least 2045, and Rijkswaterstaat will own the source code
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
ICT review board, August 2026, on the replacement project.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026)
Claim 79 clm-5c72d87bd376e929 quantitative
before 2030, because support for the hardware then ends, and calls the chance of not succeeding real
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Rijkswaterstaat's memo to the minister, September 2026.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Rijkswaterstaat — memo to the minister on the ICT review board's BESW advice (15 September 2026)
Claim 80 clm-499bb92bea7c3516 descriptive
a formal specification of BESW in which all behaviour, including manual and testing modes, is specified and all fault situations are taken into account
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The 2025 paper: all behaviour of BESW specified, including manual and testing modes, with all fault situations taken into account; verification was limited to a restricted set of water-level values and not all combinations of pump and valve failures.
Caveat
Two of the five authors work for Rijkswaterstaat, the operator.

Sources carrying this claim

  1. Beers, Booy, Groote, van den Bogaard and Bouwman — A Complete Formal Specification and Verification of the BESW software control system of the Maeslant Storm Surge Barrier (arXiv preprint, 11 April 2025)
  2. Beers, Booy, Groote, van den Bogaard and Bouwman — the same work in the FMICS 2025 proceedings, LNCS 16040 (28 August 2025)
Claim 81 clm-8dc759190f6fdb72 descriptive
the motivation was that the barrier's software control is up for replacement
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The 2025 paper on why the specification was made.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Beers, Booy, Groote, van den Bogaard and Bouwman — A Complete Formal Specification and Verification of the BESW software control system of the Maeslant Storm Surge Barrier (arXiv preprint, 11 April 2025)
Claim 82 clm-bee51fa091f217dd descriptive
the precise formal model is confidential for reasons of national security
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The 2025 paper: Rijkswaterstaat declared the precise model confidential.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Beers, Booy, Groote, van den Bogaard and Bouwman — A Complete Formal Specification and Verification of the BESW software control system of the Maeslant Storm Surge Barrier (arXiv preprint, 11 April 2025)
Claim 83 clm-be61351083531590 quantitative
From 60 cm of sea-level rise the current storm surge barriers will close more often to protect the hinterland
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Minister's letter of June 2026 on the Sea Level Rise Knowledge Programme.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Minister of Infrastructure and Water Management — letter to parliament on the Sea Level Rise Knowledge Programme, Kamerstuk 36 800 J, nr. 28 (19 June 2026)
Claim 84 clm-492424f5e7c34ef6 quantitative
replacement of the barrier is expected between 2070 and 2100, a period that coincides with about 70 cm of sea-level rise
Published field
body · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Minister's letter of June 2026: replacement of the Maeslant and Oosterschelde barriers in the period 2070–2100, expected to coincide with about 70 cm of sea-level rise; end of service life, not sea-level rise, drives the first replacement.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Minister of Infrastructure and Water Management — letter to parliament on the Sea Level Rise Knowledge Programme, Kamerstuk 36 800 J, nr. 28 (19 June 2026)

Source dossiers and revision state

This layer records what is known about each source, what is still missing, and the exact snapshot this page is rendering. A missing date, archive or hash stays visible as missing.

unreviewed Revision 2026-11-06-landmark-p6-uplift effective 2026-11-06 · created 2026-11-06

Awaiting operator and domain-expert review; publication of this revision implies neither.

sha256:86f851773458f525505312898972145620fd53fd1fa6052f911ebb4af484102a
Revision history → Permanent version link → Machine-readable record → Evidence Constitution →
84
of 84 claims mapped
22
source dossiers
16
publication dates recorded
0
archives linked
0
exact locators
0
content captures hashed

Governance facts carried by the record

Operator
Rijkswaterstaat
Actor types
national-government
Funding model
public
Funding description
Not recorded
Cost
Nearly half a billion euros (Watersnoodmuseum); €450 million, about €738 million at 2023 prices (DutchNews)
Ownership
Not recorded
Decision rights
Not recorded
Exit conditions
Not recorded

22 source dossiers

Rijkswaterstaat — Deltawerk Maeslantkering rijkswaterstaat.nl · 9 linked claims

Open original source ↗

Stable source ID
src-65db1b142fce4e27
Publisher
Name not classified · rijkswaterstaat.nl
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-11-06
Dossier created
2026-11-06
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

The operator's page on the barrier: built 1991-1997 at Hoek van Holland; two doors 210 m wide, 22 m high and 15 m deep; closing level 3 m above NAP at Rotterdam or 2.9 m at Dordrecht; closes fully automatically, with an expert team present to monitor and intervene; annual test closure every September; a verification closure at a lowered level after seven years without a storm closure.

Descriptive only — not page/paragraph exact
Claims linked
Rijkswaterstaat — Maeslantkering open again after the 28th test closure (14 September 2025) rijkswaterstaat.nl · 3 linked claims

Open original source ↗

Stable source ID
src-a742723df11b7b07
Publisher
Name not classified · rijkswaterstaat.nl
Type / language
web-page · language not classified
Published
2025-09-14
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-11-06
Dossier created
2026-11-06
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

The 28th test closure of the Maeslant and Hartel barriers on 13 September 2025 went smoothly; sailing out, closing and sinking the arms took just over two hours.

Descriptive only — not page/paragraph exact
Claims linked
Rijkswaterstaat — Look back at high water and storm Pia (21 December 2023) rijkswaterstaat.nl · 5 linked claims

Open original source ↗

Stable source ID
src-5fc9008976a3624f
Publisher
Name not classified · rijkswaterstaat.nl
Type / language
web-page · language not classified
Published
2023-12-21
Updated
2024-01-09
Source last checked
No source-level check date
Record last verified
2026-11-06
Dossier created
2026-11-06
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Live blog of 21-22 December 2023: all six storm surge barriers closed, the Maeslant barrier automatically for the first time; the first time its criterion of an expected 3.00 m at Rotterdam was reached; the 2007 and 2018 storm closures ran at a temporarily lowered level to test the systems; reopening at 04:45.

Descriptive only — not page/paragraph exact
Claims linked
Rijkswaterstaat — Interview with the barrier manager after the December 2023 closure (22 December 2023) rijkswaterstaat.nl · 1 linked claim

Open original source ↗

Stable source ID
src-55b089c8cc309f97
Publisher
Name not classified · rijkswaterstaat.nl
Type / language
web-page · language not classified
Published
2023-12-22
Updated
2024-10-21
Source last checked
No source-level check date
Record last verified
2026-11-06
Dossier created
2026-11-06
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Interview with the barrier manager: the team was alerted 24 hours before an expected 2.60 m, and the forecast then showed the water would reach 3.10 m above NAP. The article gives both 20:15 and 22:15 as times.

Descriptive only — not page/paragraph exact
Claims linked
Rijkswaterstaat storm surge warning service — Stormvloedflits 2007-09, 8 and 9 November 2007 open.rws.nl · 1 linked claim

Open original source ↗

Stable source ID
src-bd77893529b056aa
Publisher
Name not classified · open.rws.nl
Type / language
pdf · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-11-06
Dossier created
2026-11-06
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Rijkswaterstaat's storm surge report on the north-westerly storm of 8-9 November 2007: the Hartel and Maeslant barriers were closed during a storm surge for the first time.

Descriptive only — not page/paragraph exact
Claims linked
NOS — Maeslantkering automatisch gesloten, eerste keer door hoogwater (21 December 2023) nos.nl · 2 linked claims

Open original source ↗

Stable source ID
src-558708a8fac3d548
Publisher
Name not classified · nos.nl
Type / language
web-page · language not classified
Published
2023-12-21
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-11-06
Dossier created
2026-11-06
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

The barrier closed automatically because of high water for the first time; closing from 20:15, shut around 22:00.

Descriptive only — not page/paragraph exact
Claims linked
NOS — Westerstorm over hoogtepunt heen (3 January 2018) nos.nl · 2 linked claims

Open original source ↗

Stable source ID
src-11c825d021b903ed
Publisher
Name not classified · nos.nl
Type / language
web-page · language not classified
Published
2018-01-03
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-11-06
Dossier created
2026-11-06
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Storm of 3 January 2018: the barrier closed for a test and would normally not have closed; storms in 2002, 2013 and 2014 nearly closed it.

Descriptive only — not page/paragraph exact
Claims linked
Hart van Nederland — Primeur: alle vijf waterkeringen dicht (3 January 2018) hartvannederland.nl · 3 linked claims

Open original source ↗

Stable source ID
src-c3fa74ef7aa77a7d
Publisher
Name not classified · hartvannederland.nl
Type / language
web-page · language not classified
Published
2018-01-03
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-11-06
Dossier created
2026-11-06
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

All five big storm surge barriers closed on 3 January 2018; the Maeslant closing level had been lowered to 2.60 m, as in 2007; a Rijkswaterstaat spokesperson says 3 m had never occurred at Rotterdam during a storm.

Descriptive only — not page/paragraph exact
Claims linked
Minister of Infrastructure and Water Management — letter to parliament on replacing the barrier's control system, Kamerstuk 35 000 J, nr. 34 (15 August 2019) zoek.officielebekendmakingen.nl · 3 linked claims

Open original source ↗

Stable source ID
src-c10c1956d1834d30
Publisher
Name not classified · zoek.officielebekendmakingen.nl
Type / language
pdf · language not classified
Published
2019-08-15
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-11-06
Dossier created
2026-11-06
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Letter to parliament: after the 2009-2012 renovation of the control system its reliability could not be demonstrated (2014); a redesign is to deliver a demonstrably reliable system before the 2021/2022 storm season; 3 January 2018 closure in storm conditions; annual test closures always successful, including a planned manual closure in 2016.

Descriptive only — not page/paragraph exact
Claims linked
Rijkswaterstaat Zuid-Holland — Achterlandstudie Maeslantkering, main report (15 October 2006) zoek.officielebekendmakingen.nl · 5 linked claims

Open original source ↗

Stable source ID
src-ca6d3f24bccce7c2
Publisher
Name not classified · zoek.officielebekendmakingen.nl
Type / language
pdf · language not classified
Published
2006-10-15
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-11-06
Dossier created
2026-11-06
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Hinterland study: both movable parts of the Europoortkering failed their technical reliability requirement of at most one failure to close in a thousand closures; the latest failure analysis put the probability of not closing at up to 1 in 100, which an external review called realistic and achievable.

Descriptive only — not page/paragraph exact
Claims linked
Adviescollege ICT-toetsing — Advies project Vervangen BESW (19 August 2026) tweedekamer.nl · 21 linked claims

Open original source ↗

Stable source ID
src-947e470313bb369b
Publisher
Name not classified · tweedekamer.nl
Type / language
web-page · language not classified
Published
2026-08-19
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-11-06
Dossier created
2026-11-06
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Advice of the government's ICT review board on the project to replace BESW: the state of BESW has been unacceptable since the 2012 replacement; almost 100 known defects; at least four manual interventions in 17 closures; three failed repair projects; BESW fails more often than Rijkswaterstaat's models predict; one storm closure to date; legal requirement 1:100; replacement aimed for before the 2030 storm season.

Descriptive only — not page/paragraph exact
Claims linked
Rijkswaterstaat — memo to the minister on the ICT review board's BESW advice (15 September 2026) tweedekamer.nl · 8 linked claims

Open original source ↗

Stable source ID
src-cbd2addc0dbf8fab
Publisher
Name not classified · tweedekamer.nl
Type / language
web-page · language not classified
Published
2026-09-15
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-11-06
Dossier created
2026-11-06
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Rijkswaterstaat's memo to the minister on the board's advice: improvement is needed but the barrier works according to the legal safety requirements; it rejects the board's 'false certainty' characterisation but adopts IEC 61508; hardware support ends in 2030 and missing that date is a real risk.

Descriptive only — not page/paragraph exact
Claims linked
Minister of Infrastructure and Water Management — letter to parliament on the Sea Level Rise Knowledge Programme, Kamerstuk 36 800 J, nr. 28 (19 June 2026) tweedekamer.nl · 2 linked claims

Open original source ↗

Stable source ID
src-869e582e10a3cc93
Publisher
Name not classified · tweedekamer.nl
Type / language
web-page · language not classified
Published
2026-06-19
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-11-06
Dossier created
2026-11-06
Retrieved copy
No local capture recorded
Archive
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Letter to parliament on the Sea Level Rise Knowledge Programme: replacement of the Maeslant and Oosterschelde barriers in 2070-2100, driven by end of service life; from 60 cm of sea-level rise the barriers will close more often.

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Watersnoodmuseum — Maeslant Storm Surge Barrier watersnoodmuseum.nl · 4 linked claims

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src-6108dd3774730e68
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Name not classified · watersnoodmuseum.nl
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The flood museum's account: not part of the original Delta Plan; a design competition won by Bouwkombinatie Maeslantkering; brief to close at 3 m but no more than once or twice every ten years; construction from 1991, commissioned six years later by Queen Beatrix; cost nearly half a billion euros.

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DutchNews — Rotterdam's massive storm surge barrier passes its annual test (17 September 2023) dutchnews.nl · 1 linked claim

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src-65c8efcb099993ca
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Name not classified · dutchnews.nl
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2023-09-17
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On the 2023 test closure, quoting the operations spokesman: the structure is sunk slowly because dropping it would send big waves into Rotterdam; cost €450 million; the lowered level for 2007 and 2018 given as 2.65 m.

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Tretmans, Wijbrans and Chaudron — Software Engineering with Formal Methods: The Development of a Storm Surge Barrier Control System (author preprint, 7 July 2000) web.archive.org · 9 linked claims

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src-b89d0dd9cc87d31b
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Name not classified · web.archive.org
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pdf · language not classified
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2000-07-07
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Author preprint of the journal article in Formal Methods in System Design (2001), by researchers from the University of Twente and CMG: why the decision was automated, the software failure-probability requirements, SIL 4, code size, completion in October 1998.

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Chaudron, Tretmans and Wijbrans — Lessons from the Application of Formal Methods to the Design of a Storm Surge Barrier Control System (FM'99, 1999) link.springer.com · 5 linked claims

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src-d21665ba0120c0dc
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FM'99 conference paper by the developers: three years and about 25 man-years; 20,000 lines of formal specification and 450,000 lines of C++; Promela and Spin found significant errors in early designs; no line of code was completely proved correct.

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Goorden, van de Mortel-Fronczak, van Eldik, Fokkink and Rooda — Lessons learned in the application of formal methods to the design of a storm surge barrier control system (IFAC-PapersOnLine 55, 2022) homes.cs.aau.dk · 1 linked claim

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src-b37b333886a31dd2
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Name not classified · homes.cs.aau.dk
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pdf · language not classified
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Paper co-written with Rijkswaterstaat staff on lessons from the formal methods used for BOS: BOS closes the barrier based on weather forecasts, water-level measurements and flood-simulation results; expertise in the original methods has declined.

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Beers, Booy, Groote, van den Bogaard and Bouwman — A Complete Formal Specification and Verification of the BESW software control system of the Maeslant Storm Surge Barrier (arXiv preprint, 11 April 2025) arxiv.org · 3 linked claims

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src-bc2221e4cf28c8c8
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Name not classified · arxiv.org
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2025-04-11
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Formal specification of BESW in mCRL2 by researchers from Eindhoven University of Technology and Rijkswaterstaat: all behaviour including manual and testing modes and all fault situations; verification limited to a restricted set of water levels and not all pump and valve failure combinations; the model is confidential.

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Beers, Booy, Groote, van den Bogaard and Bouwman — the same work in the FMICS 2025 proceedings, LNCS 16040 (28 August 2025) link.springer.com · 1 linked claim

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src-4185f94afa6280f6
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Name not classified · link.springer.com
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2025-08-28
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The peer-reviewed version of the same work in the FMICS 2025 proceedings, Lecture Notes in Computer Science volume 16040.

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H2O — Eerste daadwerkelijke sluiting Maeslantkering goed verlopen (2007) edepot.wur.nl · 2 linked claims

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src-458a2eeaeb96b4ea
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Name not classified · edepot.wur.nl
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web-page · language not classified
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Water-sector magazine interview with Rijkswaterstaat staff after the November 2007 closure: BOS calls the team at a forecast of 2.60 m and closes at 3 m; the closure was the work of a computer; the team can switch to manual operation.

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Computable — ICT is onmisbaar bij waterbeheer (27 May 2010) computable.nl · 1 linked claim

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src-66a51d9f8f0a9941
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Name not classified · computable.nl
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web-page · language not classified
Published
2010-05-27
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IT trade press visit to the barrier: every ten minutes the computer makes a calculation for the coming 24 hours.

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