Waarnemingspost, De Bilt

English translation

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Description

Cluster 31. Three concrete observation posts with access lock.

NEW HOLLAND WATERLINE

Introduction

THREE CONCRETE OBSERVATION POSTS WITH ACCESS LOCK at Fort Ruigenhoek, as components added in the period 1914-1918 to a late-nineteenth-century fort reinforced with earthworks. One of the important functions in military operations or works was that of observing any (enemy) movements or actions. To this end, look-out posts have long been established, whereby a high position, whether or not concealed or covered, was preferred. Natural heights, various towers, balloons and aircraft have been frequently used as such. Covered observation posts have been applied in various forms, with earth and wood and ultimately iron, stone and (reinforced) concrete proving most reliable. The latter material has been applied, among other places, at Fort Ruigenhoek and at the Fort at Asperen, where during the First World War this then new material was experimented with. Reinforced concrete was later applied on a large scale and often also incorporated as an integrated component in the works. Two concrete observation posts at Fort Ruigenhoek are situated respectively near the salient of the north-western bastion and the salient of the north-eastern bastion, both thus on the Bilthoven side of the fort. The third specimen is located in the (north-)eastern flank of the fort, at the transition from the curtain to the north-eastern bastion; this is the Groenekanse side. The roof of two access locks to the observation posts is damaged. The observation posts were considered as shrapnel-free spaces. This type of observation post is relatively rare.

Description

THREE CONCRETE OBSERVATION POSTS WITH ACCESS LOCK at Fort Ruigenhoek, dating from the period 1914-1918. One is located on the north-western bastion, a second on the north-eastern bastion and the third specimen in the (north-)eastern flank. The cupolas have a monolithic construction of reinforced concrete with a diameter of approximately 1 m and a roof slab of approximately 0.25 m thickness. A periscope could be inserted through this roof. Access locks several metres long, loosely attached, of relatively thin-walled reinforced concrete, lead to the interior of the cupolas, which may still contain remnants of functional components. The rectangular access lock at the north-western observation post is still intact.

Valuation

The THREE CONCRETE OBSERVATION POSTS WITH ACCESS LOCK at Fort Ruigenhoek are of general interest because of:

* Cultural-historical values, as part of the New Holland Waterline as designed by C.R.T. Kraijenhoff and initially from 1815 realised by him, Jan Blanken and major-engineer Willem Offerhaus, and subsequently strengthened and improved by others over approximately 125 years.

* Architectural-historical values, in particular as an expression of military-strategic building practice, which is based on: a. the system of inundation and access defence (nineteenth and twentieth centuries), b. the arms race with increasingly strengthening offensive means (nineteenth and twentieth centuries), c. the system of 'living' field fortification (twentieth century).

These are rare examples of identical reinforced concrete observation posts from the second decade of the twentieth century, which also served as concrete experiments.

* Ensemble value and situational values as components of the New Holland Waterline. Also because of the functional and physical coherence with the other components of the complex.

* The components are very rare because they are scarce surviving examples of military concrete experiments for series manufacture of this type of defence measures.

* The components are fairly well preserved, while they can be recognized well through their location and function.