The same construction, vertical and slender, located at one end of the fire station’s drill yard, rises up in the interior landscape of Vall d’Hebron with two completely different purposes.

On the one hand, it is used as a drill tower, i.e. the most realistic scenario possible for training on the specific architectural elements of the city. And, on the other, concentrated on the edge that delimits it, the tower is a continuous and protective skin that dialogues face to face with the great staircase of the city.

The concrete city (the city of windows, balconies and neighbours) meets the city of infrastructures, movement and large-scale landscapes.

Flesh and skin

The tower, which is more than the sum of its parts, is made by superimposing two simulations of the city: to the east, the tangible, constructed shell forms a volumetric mock-up of reproduced cut-outs of the standard city. It is the domestic side, the side of activity, the side that is busy and alive. To the west, an abstract façade outlines the presence of the tower in the skyline of the site and invokes memory.

A tribute to the city’s contemporary architectural heritage

The prefabricated panels from the Archery Range, designed by Enric Miralles and Carme Pinós, have been piled up for years just metres from the site. This abandonment suggests working to find a memorable destination for them. Tied less to rebuilding the award-winning facility, which would require new manufacturing, a new standard, than to vindicating their memory and destiny.

We therefore propose to give them a new, more appropriate life by relocating them in a new arrangement as the exterior of the new tower, preserving their dialogue with the landscape for which they were originally designed. This way, the new tower will enjoy a functionally blind, protective skin, but emotionally it will have its own texture, meaning and history.

Sustainability

The shape and number of panels available make it possible to propose reusing these specific construction elements, becoming a manifesto on rehabilitation and sustainability.

On the other hand, considering the emissions linked to manufacturing/extracting the materials, the building mainly uses dry, prefabricated construction, optimising construction time and future recyclability. The materials used are also recycled: the structure is made of recycled steel and the opaque façades are reused parts.

A lightweight structure

The tower is built on an existing structure with four concrete pillars on a foundation consisting of a large pile cap that complies with current regulations, although it would not support a heavy tower. So, the eight-storey drill tower is conceived as an upper structural framework, which must be lightweight and in line with the pre-existing supports. It is an all-metal structure that corresponds vertically with the concrete structure and distributes its structural stresses by concentrating the resulting load in the joint area formed by the four pillars. The weight of the rest of the construction elements (floor slabs, façades and stairs) is also minimised, built out only where absolutely necessary to serve its function, leaving the structure visible on all other surfaces. The metal structure will be treated according to regulations and the specific requirements of the activity to be carried out. This both minimises its weight and distributes the effects of the new construction on the original base.

The functional programme

The main structure is the support to which a wide variety of secondary, specific constructive solutions are attached to serve the many different physical exercises (the programme) that the tower will be used for. These are:

– Reversible Shaft Drill: The start of the vertical shaft is located on P1 or the Lobby Floor, providing a large enough space for a tripod and the group of people around it. The shaft goes down to P-2, the Basement Floor, meaning the drill can be done from the top down or bottom up.

– Visibility drills: The plan is to be able to do these exercises anywhere in the tower, from the underground floors through the whole height of the tower. The façade, which is partially open, can be closed using curtains when visibility drills are being carried out.

– Shoring drills: the various geometric, material and construction set-ups of the stairways and floors allow for a wide variety of situations.

– Vertical rescue through the light shaft: in the vertical space between the structure and the main façade, which stretches the whole height of the tower.

– Vertical rescue drills on the façade: all the required arrangements of the façade plane (setbacks) and configurations of openings in the façade (windows, balconies, railings, etc.).

– Climbing through an adjacent open structure, which presents vertical continuity but also the possibility of having to turn corners.

– Vertigo drills: the flat upper roof provides a usable space from which to attach an off-centre plank spanning the void.

In terms of the general evolution of the shape of the tower:

– The P-2 and P-1 floors are intended for visibility and vertical rescue drills.

– The Ground Floor is an independent lobby. The staircase is continuous from Floor -2 to Floor 8 but is divided into two sectors that differentiate the P-2/P-1/GF assembly from the aerial part of the tower. The porticoed area at ground level provides a space for shelter and risk prevention for vertical activities in the tower and a shaded area for giving instructions before starting the drills, with a blackboard on the wall.

– The first floor is larger (within the permitted surface area) and serves as a lobby in the tower. This provides a comfortable space for group meetings, well protected and differentiated from the daily activities in the drill yard, allowing both activities to take place without interference.

– The P1 Lobby has a higher ceiling (350 cm) than the rest of the upper floors (250 cm), allowing the use of non-standard shoring.

– From the second to the eighth floors, the tower is designed with a variety of types of façades and spaces, with samples of different constructive solutions and materials, such as the different geometric configurations of a staircase and different material characteristics (concrete, thin-tile vault, etc.).

The formal “deformation” of the tower is the result of its intense “customisation”, in order to concentrate as many different cases as possible into the space.

Construction elements

The staircases, floors and façades are made of lightweight concrete elements enhanced with metallic fibres to make sure they are rugged enough to stand up to the highly demanding use. The precast façade panels, eight centimetres thick, will have a grid of holes where hooks can easily be attached, for example for the climbing walls.

The panels are anchored to the main structure, so it would also be possible to consider reconfiguring or implementing it in the future.

The precast concrete panels from the Archery Range, 16 centimetres thick, also lightened by the triangular holes that characterise them, will be hung on the structure as a large cladding canvas, which will form the façade of the tower in the city. In this case, the function of the façade is to protect the immediate surroundings and, therefore, it will envelop the structure continuously.

Description of the construction process

The construction of the tower, which will have to be built from the yard itself while the fire station is in use, requires a quick, clean construction process, with special attention to safety measures.

– PHASE 1: Preparation of the base. The transition to a light metal structure is prepared on the head of the existing concrete pillars, at the level of the slab of the drill yard. Supporting plates, crowning beams and base for the four new supports, occupying the thickness of the existing deck slab.

– PHASE 2: Construction of the main metal structure and secondary substructures. Combination of profiles and measurements that allow assembly to be systematic.

– PHASE 3: Stairs and prefabricated lightened-concrete slabs. Prefabricated stairs, emulating turns, and pre-slabs of lightened concrete with recycled metal shavings, for all landings. Repetition of sizes and shapes. Striking a balance between the necessary lightness (concrete) and the necessary strength (partially in situ).

– PHASE 4: Laying of prefabricated façade panels. The prefabricated panels are hung and dry-fixed to the metal structure. The newly created panels will take advantage of the anchoring system used for handling and transport as a socket for future training exercises. The recycled panels are fixed using reinforcing ribs.