Maintaining road pavements to improve Europe's road safety
The UN Road Safety Collaboration has developed a Global Plan for the Decade of Action for Road Safety 2011-2020, which is officially launched on 11 May 2011. COST Action 354, ‘Performance Indicators for Road Pavements’, has been working towards a common set of indicators and a tool to manage these, boosting both the potential safety and management of the European road network across Europe.
Every driver wants to drive on safe and comfortable roads – the onus is therefore on decision-makers and road operators to be able to create and sustain an efficient and safe road network. COST Action 354 is here to help.
It’s easy to know a bad road when you drive on it, but defining what a bad road is seems to be more of a challenge. The European road network has several diverging road management approaches which each define the conditions of a road differently. From ‘transverse evenness’ to ‘skid resistance’ each road administration can use different parameters of technical characteristics to assist their maintenance plans and, significantly these can vary not just from country to country but also within the same country.
What to do about it?
COST Action 354 ‘Performance Indicators for Road Pavements’ has the answer. It is working towards a common European methodology to define uniform performance indicators and a common maintenance tool to be used across Europe. Significantly, as the Chair of the Action, Prof Johann Litzka, underlines this methodology has to take both “the needs of road users and road operators into account”.
A system of ‘performance indices’ has been defined to indicate the condition of a road, using the relevant technical characteristics. The Action has taken into consideration the wide variety of potential users of this system and ensured that within this common framework, procedures can be applied in different ways, depending on the type of measurements available and the analysis approach undertaken by each road authority.
A score from 0 (very good condition) to 5 (very poor condition) can be given to each index to ensure the assessment is an objective one – and these have been defined for each of the major areas of maintenance, which are:
- Longitudinal evenness;
- Transverse evenness;
- Bearing Capacity;
- Air Pollution;
- Surface defects.
What is not included here are noise pollution indicators, but although very important, the Action found there is sadly insufficient data to monitor their influence to be able to include them.
There’s a second aspect of the methodology, derived from the list above, and this is the development of four combined performance indices. Each of these represents important aspects of pavement performance relevant to road users and road operators. These four indices cover safety, comfort, structure and environment and this ‘Combined Performance Index’ characterises the contribution of the pavement structure and condition to the performance of the road.
The final layer used within the methodology is a ‘General Performance Indicator’ which is a mathematical combination, which combines the other two indices in order to give an overall impression of the road pavement’s condition – and allows badly performing sections to be identified. With all of this information at the maintenance authorities’ fingertips, a general maintenance strategy can be derived. This ensures that decision makers have a useful tool to assess the general condition of the network and to evaluate future strategies and consequent funding requirements.
A prototype tool
A methodology is a good start but the Action has gone further by developing a tool to facilitate the calculation of each of the three indices. This tool has already been used to conduct a comprehensive sensitivity analysis. This analysis has demonstrated the effects of changing the weights of the input parameters on the one hand and the influence of modifications in the recommended combination procedures on the other.
The tool can be provided by COST Action 354 on a CD-ROM and can also be used to implement examples of the calculation of the different indices, using actual data available to a road administration. Through the indices defined and the tool developed this Action has ensured a big step towards a more integrated approach in the management of the European road network.