10.06.2015 - Ausgabe: 2/2015

Barrier-free construction

By Prof. Irene Lohaus, Lohaus + Carl GmbH Landschaftsarchitekten + Stadtplaner

According to Germany's Federal Statistics Office, 7 million people with a serious disability live in the country, equivalent to about 8.9% of the total population. The majority of them are aged over 55, and almost a third have even passed the age of 75. Against the backdrop of demographic trends, it is expected that we will experience a continuous increase in the number of people with different types of disabilities in future.

Medical progress and the development of technical aids as well as navigation and communication tools will doubtless assist many of them, but an environment designed to be barrier-free and taking into account the needs of all users will also remain essential in the future and should be a matter of course. It is already the case that many people are benefiting from the implementation of barrier-free planning and construction.

 

Designing barrier-free solutions

For most of those involved in planning, meeting the requirements for people with impaired mobility is now simply part of their everyday work. Since 2010, the standards "DIN 18040 – Part 1: Barrier-free construction" and "DIN 18040 – Part 3: Public circulation areas and open spaces" include requirements covering the needs of people with mobility, visual, hearing or cognitive impairments. Planners are, however, less familiar with these. The introduction of the "protection target" concept has furthermore defined characteristics of barrier-free construction, which have to be achieved, rather than specific solutions. The solutions presented in the DIN are therefore to be regarded as examples and not necessarily as unique solutions.

Both amendments to the DIN present a challenge to the creativity of those designing structures. They assume, on the one hand, broad background knowledge of barrier-free planning and construction and, on the other, a thoroughly transparent planning process.

 

Surfaces as an orientation and guidance system

When a site is being developed, a coherent and consistent orientation and guidance system must be available to those visiting or using structures that can be accessed by the public.

The aim must be to create a common system for guiding all users when public buildings and open spaces are being developed internally and externally. Orientation and guidance systems make a key contribution to directing people with visual or cognitive impairments and all other users clearly and safely to their destination. There is an urgent need to consider the uniformity and consistency of the selected system within the context of its use if learnability, and therefore orientation, are to be facilitated.

In the model project for barrier-freedom in the historic town centre of Warburg, the criteria on barrier-free construction, which are set out in the current regulations, have generally been met. As the design was drawn up back in 2009, before the publication of the current norms, and due to the great limitations inevitable when undertaking construction in such a setting, it has sometimes been necessary to deviate from those norms.

 

Example  Barrier-freedom in the historical town centre of Warburg – Designing the streets

 

The picturesque charm and coherent architecture of Warburg's historical town centre attract visitors and citizens alike.

One of the main objectives when creating contemporary designs for public spaces in the Neustadt has been to strengthen the historical ensemble, with its very special flair, while at the same time ensuring compliance with the current use requirements in relation to barrier-freedom, attractiveness for tourists and daily life.

One contribution to this comes from the uniform surface, which integrates well into the historical ensemble, linking to traditional decorative and architectural elements of Warburg and interpreting these in a modern way, but also takes into consideration the requirements for barrier-freedom.

 

Overall concept as the basis for an orientation and guidance system

In Warburg, an individual, uniform and comprehensive concept for the selection of surfaces was developed that takes account of the many ways in which the old town is used. It takes into consideration not only the needs of people with impaired mobility, but also creates clear zoning as well as an orientation and guidance system for those with visual and cognitive impairments.

The overall concept, which is being implemented street-by-street in annual construction sections, guarantees the consistency and comprehensiveness of the selected system in the context of the uses to which the old town is put, and that system is easy to learn. 

 

Zoning principle as the basis for an orientation and guidance system

The structure of the chosen surface reflects the historical form of the street spaces at the turn of the century. Diagonally paved paths run through the streets, which have, moreover, been created using a mixture of small and large paving stones. As the historical streets are narrow, a 1.2 metre path was created on each side.

As a minimum, these paths have been provided with a surface texture permitting safe walking and kept free from any built-in elements, displays, advertising structures and parking vehicles. This has also been clearly agreed with local business people! This zone, which is unequivocally to be kept clear, benefits not only to those with impaired vision or mobility, but also offers all users, residents and tourists unambiguous, consistent guidance as they move through the historical old town.

At 1.2 metres, the width of the paths is also the minimum width necessary for wheelchair users. As the paths are at the same level as the roads, there is also room to move sideways when, for example, one wheelchair meets another coming in the opposite direction. To facilitate usability for wheelchairs and walker-rollators, a transverse gradient of 1.5% to 2% has been selected for the paths. The differences in height between entry points typical of old town settings have been compensated for in the lateral surfaces and the central zone.

The "inner city" of Warburg is partly a pedestrian zone, although residential traffic and parking are provided for predominantly in the narrow streets. Even surfaces right across all streets have been planned.

All the paths are made of bright dolomite or concrete paving, while the roadways and accompanying pavements are made of greywacke alternating between darker beige-brown-grey.

The roadways of residential streets with a high volume of traffic, in particular those with regular buses, are made from coloured greywacke asphalt. Their colour thus blends into their surroundings.

 

Surfaces as an orientation and guidance system

In the pedestrian zone, paved surfaces made of greywacke of ashlar quality with a mottled surface are used. The diagonally laid paths made of dolomite are manufactured from sawn stones whose surface has been sandblasted. Thanks to their more precise joints and level surface, these qualities of stone offer a high level of comfort for pedestrians and drivers, while also maintaining a visual appearance appropriate to the natural stone material and historical environment.

The significantly different way in which the path and the central zone have been laid, and the supplementary framing of the path with tactile small paving stones made of greywacke, enable blind people to find their way by means of touch. In addition to this, tactile fields that draw attention and direction-signing fields (stainless steel studs as surface indicators) have been integrated into the path where there are crossings and entry points.

Perceptibility for the visually impaired is ensured by using materials for the path (dolomite) and surface (greywacke) that achieve a luminance contrast of 0.4, when dry or wet. This contrast value, which is recommended in the regulations, has been demonstrated in laboratory testing.

 

Limited design scope

The introduction of the "protection target" concept into the DIN provides the opportunity, for example, to develop creative, tailored solutions for listed properties, but precisely with regard to the impairments of vision now to be taken into account under the DIN, the design scope for outdoor spaces is low.

For instance, the contrast and minimum luminance values for guidance and orientation systems formulated in the DIN can only be attained by combining very dark and very bright materials. In the absence of knowledge of whether other solutions might also achieve the protection target for guiding and orienting people with sensory impairments, it is to be anticipated that the values set out as examples in the DIN will mainly be applied. Here, more advanced scientific research or model projects could result in a wider range of solutions.

 

Transparent planning process

A transparent presentation of decisions about the selected solutions is key to demonstrating compliance with the characteristics defined in the protection goals. As an interdisciplinary undertaking, the departments responsible for social and health buildings and agricultural construction of the TU Dresden, as part of the "Zukunft Bau" (Future of Construction) research initiative of the Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety (BMUB), have developed guidelines on barrier-free construction. This provides a framework for transparently documenting the agreed solutions at each planning stage.

To facilitate communication with the participants and make it more reliable, these guidelines define, for each planning phase from needs planning through to execution planning, the minimum aspects of barrier freedom to be addressed. For each planning step, the results are to be documented both in writing and in the form of drawings.

Moreover, the guidelines include sample captions for the evidence of barrier freedom in drawing form, which when used regularly make it easier to read, and consequently facilitate communication with the building authorities and those representing the disabled, particularly in the case of complicated measures for new construction and remodelling. In 2014, applying the guidelines became mandatory for federal government construction projects.

 

Photo: Lohaus + Carl GmbH Landschaftsarchitekten und Stadtplaner