Overview
The standard of road infrastructure differs throughout the European Union Member States. In general, the means of transportation are of a lower standard in the new Member States, but the present volume of heavy road transport requires a sustainable road infrastructure immediately.
There is a constant need for new resistant pavement materials that should comply with EU regulations. Due to the priority of motorway construction, the standard of maintenance of other roads has fallen, resulting in an increased need for effective road maintenance and improvement over the years to come. The materials and technologies now used in the new Member States differ from those adopted in common practice in the EU-15.
SPENS focuses on developing procedures for producing and implementing improved materials for road construction, taking into account the local tradition, the availability of materials and construction techniques, as well as the specifics of roads that have already been constructed.
The research work will concentrate on the assessment of existing road conditions and maintenance planning, on pavement renewal and the upgrading of roads, and on the environmental impacts of roads.
The overall objective of the SPENS project was to generate knowledge to enable a more rapid rise in the standard of road infrastructure, by developing appropriate tools and procedures for long-lasting and more cost-effective improvement of roads.
Efficient and economic rehabilitation of the existing road network could be attained if reliable and scientifically based information is available on both present pavement conditions and current actions about pavements. A new systematic decision-making methodology about pavement rehabilitation and upgrading would contribute to sustainable surface transport.
The proper use of new techniques, such as reinforcing pavements, could bring economical and ecological benefits. Guidelines would indicate the best practice on how to use these methods and materials.
The development of new techniques, which allow for the incorporation of recycled waste materials of different origins into building materials for roads, would contribute to savings in natural raw material resources.
An uneven and rough road surface gives rise to higher fuel consumption, exhaust emissions, costs for vehicle wear and road traffic noise. The research would contribute towards the implementation of pavement types with high durability. Instructions for the selection of pavement types with low noise emissions can reduce the cost for noise abatement measures, which are a growing cost factor in the construction of new roads.
The research work was organised into four technical work packages, and addresses the specific problems of the new Member States.
Since financial resources for road maintenance and rehabilitation were very limited, sophisticated pavement management systems could provide results upon which long-term optimum decisions could be made. The research of one work package focused on techniques for gathering the proper input parameters and the development of a systematic methodology analysis of the deterioration caused by traffic.
The research work outlined in the work package 'Improvement of pavement structures' showed the potential of new techniques for the improvement of new and existing flexible road pavements. For example, the efficiency of different kinds of reinforcement for road widening and rehabilitation were established, and a practical model for the optimisation of an asphalt mixture design was tested. Within this work package the benefits and limits of waste and by-product materials, including recycled materials, for road construction were studied.
Evaluation of materials and pavement layers appropriate for road upgrading were analysed in a separate work package, which focused on modified bitumen as asphalt binders, high modulus asphalt mixtures, and their actual field performance. Laboratory work was concerned with a number of mixtures, the most promising of which were tested in the field, taking into account the specific climate and traffic loads.
The work package 'Assessment of the impact of roads on the environment' focused on the characterisation of different types of road pavements with regard to environmental features and traffic noise emission, taking into account the typical compositions and pavements used in the new Member States.
The research work gained from clustering with other on-going research projects, but was oriented towards implementation, and focused on the issues which were the most important for end-users such as road administrations and contractors.
Funding
Results
The scope of the SPENS project was sufficiently wide that results might be seen to be output at each and every stage and workpackage. While diverse, its principal results might be seen to be:
- The development of a systematic decision making methodology for pavement rehabilitation and upgrading of low-volume roads in Central and Eastern European countries, based on skid resistance, transverse unevenness (rut depth), surface defects, longitudinal unevenness and bearing capacity, and using techniques such as, resurfacing (surface dressing, slurry seal, thin overlay), overlaying, pavement strengthening (upgrading by asphalt layers, 'sandwich systems', recycling) and reconstruction.
- A wide range of findings regarding the reinforcement of pavement bound and unbound layers including the production of a user-friendly pavement design methodology and best practice and practical guidelines. Once conclusion was that the use of reinforced structures may prolonged the service life of pavements by more than 20 per cent.
- The demonstration that crushed concrete can be a good and environmentally acceptable replacement for natural aggregate for construction of unbound layers and that no practical problems seem to exist in its use. Crushed concrete was found to show better long term behaviour than compared natural aggregate with no negative environmental effects.
- The software package 'Programme for Asphalt Mix Design and Optimisation' (PRADO) was developed for the analytical study of asphalt mixture composition by volumetric calculation and can be used for prediction of complex modulus of asphalt mixture from rheological properties of pure binder and prediction of mechanical properties and performance of a mix.
- It was determined that asphalt mixtures with a softer type of binder can be used for regions with lower temperature and traffic volume where it is important for asphalt pavement to have good resistance to fatigue and thermal cracks, while in regions with higher temperature and higher traffic volume, it is recommended to use harder types of binder. These binders cannot be used for asphalt pavements in regions with extreme daily temperature changes and roads with heavy traffic.
- The demonstration that noise emission from NMS road surfaces is comparable to that of standard road surfaces in the rest of the EU. Asphalt concrete and SMA surfaces dominate, and problems are usually due to the use of old types of concrete surfaces or bad maintenance condition. SMA paveme