Road transport provides over 80 percent of all transportation in Europe. A well maintained road infrastructure is therefore essential to Europe's economic and social development. Maintenance of the road infrastructure calls for structured planning, taking into account the life-cycle costs of the fabric of the roadway (or pavement) and the consequences for road users in terms of delays and risk of accidents at lane changes and closures associated with the execution of maintenance.
The objectives of PARIS were:
- to develop road pavement deterioration models for use in road pavement management systems;
- to produce uniform definitions, data acquisition and analysis methods to interpret road pavement performance;
- to develop a central research database for road pavement condition data gathered in the participating countries;
- to validate the road pavement deterioration models developed.
PARIS developed a coherent set of road pavement performance models based on real-world data from all participant countries and additional data from accelerated loading tests. The models produced are suitable for use in the daily practice of road pavement management, and they only require input parameters that are readily available to the road pavement manager. Further, they describe the part of the evolution of damage (or distress) that is of relevance in the planning of road pavement management.
Significant recommendations are:
- The models developed should be tuned or calibrated for local conditions. Although they are based on a large and high quality data set covering most of Europe, they are not necessarily suited for direct use in local road pavement management systems.
- The models developed are based on data from detailed distress surveys, whilst in practice rather less detailed information is available. Therefore, there is a need to assess the influence of less detailed input parameters on the output of the models by undertaking sensitivity analysis.
- The method for distress data acquisition should be adopted as the standard for future road pavement performance studies.
- Safety and environmental factors should be included in future studies by gathering data on performance indicators such as skid resistance and tyre-road noise.
- Further analysis should be done on rigid road pavements, because structured data on the long-term performance of this type of road pavement are scarce in Europe.
- Road pavement performance studies should be focused not only on newly built road pavements, but also on road pavement maintenance treatments. Such information is essential to the selection of maintenance strategies.
- Life-cycle cost analysis procedures should be developed for road pavement performance, based on European practice.
The main policy conclusions from PARIS are the following:
- The development of European road pavement deterioration models is important for a better harmonisation of infrastructure maintenance across Europe.
- A new more sensitive measurement should be adopted at the European level in place of the International Roughness Index IRI for the high quality primary network of Europe, this parameter was found inappropriate for use in maintenance management.
- A European standardisation will be needed to derive Equivalent Standard Axle Loads (ESALs) from traffic counts: too much variety in the current methodology exists in the European practice of road pavement management.