Bomvrij militair object, Betonnen werken Ruigenhoek-De Gagel De Bilt

English translation

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Description

Cluster 32. Group Shelters Type P.

NEW HOLLANDSE WATERLINIE

Introduction

GROUP SHELTERS TYPE P are twentieth-century, serially built, additions to the existing defence. At various locations on and around the Forts de Gagel and Ruigenhoek, Group Shelters Type P are located. Most are in the area between and around these two forts and the more westerly Fort Blauwkapel. Most of the remaining (11) are on Fort Ruigenhoek and are counted as part of this fort, respectively Fort de Gagel (3). (Concrete) (group) shelters formed an answer to the arrival of heavy projectiles and high-explosive grenades. The latter have a highly explosive charge. Depending on the weight of the artillery and the protection against it, there has existed since 1928 a classification in resistance or protection classes, consisting of two numbers, for example W 12-15. The first indicates that the protection is sufficient for impacts of projectiles up to that calibre (in centimetres); the second that protection also exists against one or at most a few impacts up to this higher calibre. The earliest types of concrete shelters offered only protection against grenade fragments and were called 'shrapnel-proof'. The group shelters Type P were built in accordance with more or less uniform or standard design in the years 1939-1940 at multiple locations in the Netherlands. The total number of built examples amounts to approximately 700, of which around 570 in the Nieuwe Hollandse Waterlinie; the majority (approximately 400) of these still exist. The building programme of the group shelters Type P was not yet completed at the outbreak of the Second World War and a number of examples have remained visibly unfinished. Type P (also called 'the pyramid' because of its striking shape) is presumably the most well-known type of concrete fortification in the Netherlands. The type arose from the so-called VIS 77 (Regulation for Arranging Positions no. 77), from 1928, and had among other purposes the intention to form part of the defence of a number of new accesses, including in particular (express) roads. The group shelter Type P usually came into being in the immediate vicinity of already existing or contemporaneously realised casemates, gun emplacements, fortifications or trenches. The front side or front face of the group shelters Type P, which was entirely closed from old times, was intended to be covered by earthworks, which could form part of a glacis for the protection of the trench or a covered way. These earthworks are now mostly no longer present or only with difficulty recognisable, but particularly on forts or in otherwise terrain characterised by relief, there is sometimes still coverage. There are various variants of Type P, both in terms of dimensions and protection class as in execution and detailing. For example, there are specimens built in the protection classes W 12-15 and W 21-28 with dimensions ranging from approximately 5.50 by 7.20 by 4.70 metres to 6.50 by 8.20 by 4.90 metres (width by depth by height). Many specimens of Type P were built in inundatable areas, whereby in a number of cases a visibly revealed pile foundation was applied, while often a retaining wall or trough with steps against inundation water was introduced in the then high-situated, square access, and in yet others a concrete foundation plate projecting all around is present. The specimens within the complex Works between Fort Ruigenhoek and Fort De Gagel are largely located in a recognisable linear relationship that extends from Fort de Gagel, via Fort Ruigenhoek to Fort Blauwkapel. More than twenty Group Shelters Type P belonging to the same linear relationship are located on these three forts.

Description

In the municipality of De Bilt, six GROUP SHELTERS TYPE P are located. These are single-storey, usually in reinforced, approximately 100 to 180 centimetre thick cast concrete executed, grenade-proof, military quarters, which could provide shelter for ten to twelve men of infantry / artillery. Group Shelters Type P are built on a rectangular ground plan. The visible height above ground level varies. Both blind side facades and the rear side are executed vertically to approximately three metres in height. Above this, these facades slope inwards at an angle of approximately 45 degrees, then proceed to a flat roof. On the right in the rear side is an (subsequently either or not blocked up) access opening at locally varying height above ground level. The entirely vertical, closed front face reflects the 45-degree angles and thus ends as a 'truncated pointed gable'. In a number of cases, iron hooks were cast into the facade(s) which could serve for the fastening of camouflage material. A characteristic component on top of the shelter type P is the conical, concrete 'outlet', which was intended for the use of a periscope. These periscopes were, however, never actually fitted. The interior of the Group Shelters Type P consists of a short corridor (usually with a concrete retaining wall or balustrade and usually a few descending steps) and a 'lock' directed from there to the left which could be sealed by a (consisting of several parts) heavy, steel door with bolts. Via a second, comparable door, a rear-lying, virtually square room could be reached by turning right, the actual shelter. The access could be commanded from this room via a loophole. The doors were, however, seldom or never fitted in practice. The ceilings located at approximately two metres above floor level are flat and rectangular. In a number of cases, interior components are still present, such as (remains of) wooden benches or a support for the firearm for the command of the entrance. The Group Shelters Type P within the complex Works between Fort Ruigenhoek and Fort De Gagel are (almost) without exception visibly and recognisably located in the terrain, albeit far from always in accessible areas. An earth covering is not (any longer) present; however, traces or (reconstructed) parts of trenches / small group positions are here and there evident.

Valuation

The GROUP SHELTERS TYPE P within the complex Works between Fort Ruigenhoek and Fort De Gagel are of general interest because of:

* Cultural-historical values as part of the Nieuwe Hollandse Waterlinie as it was designed by C.R.T. Kraijenhoff and initially from 1815 by him, Jan Blanken and major-engineer Willem Offerhaus was realised and subsequently by others for approximately 125 years strengthened and improved.

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

These are components from the period 1939-1940, namely concrete military personnel shelters.

* Ensemble value and situational values as part of the Nieuwe Hollandse Waterlinie in general and because of the mutual functional, functional-spatial and physical coherence with the other components of the complex and the Forts de Gagel, Ruigenhoek and Blauwkapel, where small concrete works belonging to the same adaptation of the defence system are located.

* The components are representative (characteristic) because they are clearly recognisable as components of a de-concentrated defence line added to the existing fortification system.

* The components are reasonably well preserved and are still clearly recognisable in the field as built components.