Published on: December 16, 2025, 10:36 AM
The monumental Lange Jaap lighthouse will be renovated and stabilized, as decided on Tuesday, December 16, 2025, by the minister of the Ministry of Infrastructure and Water Management. The decision was made based on thorough research by Rijkswaterstaat, Movares, and Strukton.
This marks a new phase for the lighthouse, moving towards restoration.
Research Provides Sufficient Confidence for Decision
In 2025, research was conducted on the feasibility of the renovation and stabilization scenario. In this scenario, the lighthouse is kept as original as possible by repairing damaged structures and adding structural elements where necessary.
As much as possible, existing materials are used. To explore the feasibility, research was done on materials and constructions:
- Cast iron: Tests on existing fragments confirm that the material behaves as expected for historic gray cast iron. The established calculation values are used in structural calculations.
- Iron cement joints: The historic iron cement has been successfully reproduced, enabling joint repairs.
- Wind load: Wind tunnel research provides more realistic data than standard calculations and offers better insight into the towers behavior under strong winds.
- Temperature measurements: New temperature data lead to more accurate calculations of thermal stresses.
- Foundation: The foundation is in better condition than expected and currently meets requirements, although further research is ongoing to determine necessary measures to limit future deterioration.
Research addressed the main question from the study phase: whether the structure could be restored. Initial results for metal stitching, the intended method to repair cracks, are positive. Additionally, realistic options are available for sustainable preservation of the cast iron.
The chosen scenario assumes restoration of the existing structure. Damaged parts are repaired and structural elements added where needed. The historic construction method is preserved as much as possible, respecting the towers monumental value.
Additional Research
At the time the decision was made, not all research was completed. Feasibility has been demonstrated and work continues on practicality. Rijkswaterstaat expects to manage this within its own organization.
Recent additional research results provide sufficient confidence to enable earlier decision-making. Work continues on the final design, and construction is expected to start in the second half of 2026, subject to necessary permits.
Two Other Cast Iron Lighthouses
Besides the Lange Jaap lighthouse, Rijkswaterstaat manages two other cast iron lighthouses: those at Scheveningen and Westkapelle Laag. These two were built similarly and have, to a lesser extent, comparable issues as Lange Jaap.
Based on experience gained from designing the Lange Jaap lighthouse, the two other cast iron lighthouses may be renovated in parallel or consecutively. The timing and order are not yet known.