Page 6 - Research and innovation un materials applied to railways

interface with the base metal and also innovative solutions based on plastic-ceramic
materials. Surface technology and the development, analysis and improvement of coatings
also has a relevant impact on aerodynamics which is ever more critical with the increase
of speed, as it is possible to control the separation of the boundary layer in order to reduce
aerodynamic resistance.

Finally and regardless of the materials used in the structure of the vehicle, the
requirements of weight, cost and especially onboard comfort, entail the use of new
solutions and interior materials with improved insulation properties and acoustic and
thermal absorption. The seat is one of the most relevant factors in comfort perception.
Traditionally these have been manufactured using metallic structures and polyurethane
foams. This component is benefitting from the use of new materials, such as silicon or
melamine resin based foams, which increase mechanical resistance, reduce weight and
improve comfort.

III. PLATFORM AND TRACK

The huge developments in High Speed and the increase of the loads transported by
vehicles, amongst other factors, is driving forward the constant evolution of railway
infrastructures. This also needs to adapt to growing demands in terms of cost,
maintenance and durability, noise and vibrations. The use of new materials to meet these
demands is one of the keys of national and European R&D&I programmes, including the
Shift2rail initiative.

The key to respond to these demands is the incorporation of elements with adequate
elastic and durable properties. Rails, sleepers, track bearing plates, baseplates, under-
ballast mat, new ballast compositions, bituminous sub-ballast, are some of the key
elements that provide a response to these demands.

Bituminous blends not only improve the vibratory behaviour of the track, but they are also
capable of increasing its carrying capacity, stability, resistance to deformation, capacity to
protect the rest of the infrastructure or its durability, with reference to the traditional
system. Furthermore, it implies a reduction in delivery time and could even signify a
reduction in the costs of construction. However, once again the increasing demands for
speed, load and frequency make it necessary to revise the solution.

For example, the modification of bitumen through plastomers or elastomers is capable of
improving its behaviour and life span. This wide spread solution faces environmental
challenges which is driving forward the search for solutions based on re-used materials.
Rubber dust from out of service tyres, lamp black or recycled fibre fillings are some of the
environmentally friendly solutions that are being proposed.

Bituminous materials can be advantageous for sub-ballast layers. The high density gravel
and sand layers have been making way for bituminous solutions manufactured from hot
mix asphalt. The behaviour and durability of this type of solution in service conditions are
becoming the object of research with the aim of optimizing its design and composition.
Furthermore, environment related issues are pushing forward the search for new
solutions, based on low temperature asphalt mixes or the valuation of re-used or recycled
materials.

Position Paper: Research and innovation in materials applied to railways 5