How can you view the striking Lange Jaap lighthouse inside without entering it? This is because of safety reasons, this is not accessible. A special drone inspection gives a solution. Last week, the almost 70 meter high lighthouse was viewed from the inside by means of the globular Flyability Elios 2 inspection drone.

National Monument

The Kijkduin lighthouse, better known in the region as Lange Jaap, was built in 1877, with its height of more than 63 meters, it is the tallest lighthouse in the Netherlands. The tower consists of cast iron plates, which are attached to each other by means of screw connections. Thanks to its striking construction and historical value, the lighthouse was designated as a National Monument in 1988.

At the end of 2021, however, during an inspection, it appeared that large cracks had arisen in the walls of the tower, which is managed by Rijkswaterstaat. It was immediately decided to turn off the surroundings of the lighthouse. Also, because of the danger of collapse, no one was allowed to enter the tower anymore. This is much to the sorrow of local residents, for whom the Long Jaap is of great emotional significance.

Drone inspection

To assess the state of the construction over time, Rijkswaterstaat commissioned a special drone inspection last Wednesday. In addition, a spherical drone of the type Flyability Elios 2 was brought inside via the entrance door. At a safe distance, the drone could then be led up along the walls. TNO had concluded in advance that the tower was approachable to be able to carry out the inspection at all.

The inspection was carried out by engineering and consultancy company Nebest B.V., in collaboration with Terra Inspectioneering. “The purpose of this drone inspection is to conduct a visual inspection of existing damages. These were marked earlier during the baseline. With the drone, we want to check whether the cracks have gotten worse or not since that time,” says one of those involved.

The height of the tower in particular proved to be a challenge. “First, the question was whether the signal transmission would remain sufficiently stable over that distance. But that proved to be no problem. Secondly, you can’t possibly bring everything into the picture. We are talking about 17 floors and 4 rings per floor. The images made have to be analyzed afterwards, and that is quite spicy. We have therefore limited ourselves to looking at the existing damages.”

Flyability Elios 2

The choice for the Flyability Elios 2 was obvious. Thanks to the spherical roll cage, this drone can literally take a beating. For that reason, this drone is often used for industrial inspections of hard-to-reach locations. The drone is equipped with a high resolution camera and a built-in LED floodlight, so that the walls to be inspected can be well lit.

It was unique that those involved were able to watch along during the inspection flight, via a screen that was set up at a safe distance from the lighthouse. On that, the live camera image was seen from the drone.

Next step

The next step is to process all data and prepare an inspection report. On this basis, the client Rijkswaterstaat can help determine the possibilities to preserve the lighthouse.