Roads require maintenance works during all their life cycle, depending mainly on traffic intensity (focusing on heavy vehicles), time and environment. There are three basic types of maintenance strategies: preventive, corrective and replacement.
- Preventive maintenance keeps the road to a stable level service, avoiding the roads to deteriorate quickly.
- Corrective maintenance prevents the road elements or section to reach a high level of damage with large-scale interventions, such as integral or structural rehabilitations.
- Replacement program applies when the road has reached to its service life and rehabilitation works are highly required.
The degradation rate of a road asset is not linear. After an initial drop of the road condition in the first years (Point 1 “Initial Loss of Quality”), the asset tends to maintain a fair condition for the majority of its life. However, after the 75% of pavement lifetime (Point 2 “Structural Loss”), the deterioration rate increases exponentially, worsening drastically the road condition.
Evolution of maintenance / rehabilitation cost over time and road condition
In order to extend the road’s lifespan, a combination of preventive and corrective maintenance activities applies at different stages of the asset’s service life (with more emphasis on the former), even a rehabilitations program may be applied at some point.
Therefore, from the technical-economic point of view for the road operator, the maintenance strategy seeks that the road condition would be between Point 1 “Initial Loss of Quality” and Point 2 “Structural Loss”, although much closer to Point 2.
The complexity comes when incorporating the user costs in the overall economic analysis, from the perspective of country competitiveness. Poor road condition influences negatively in road user costs: higher vehicle maintenance, higher fuel consumption, longer journey times, lower comfort, higher safety risks, etc. Thus, the worse the road condition, the higher the overall cost for the user.
With this new perspective, the optimal level of conservation of the road is determined by the sum of the maintenance cost and the cost for the user. As a result of this analysis, the optimal conservation level moves closer to Point 1 “Initial loss of Quality”, against the strictly economic interests of the highway operator (closer to Point 2 “Structural Loss”).
Optimal level of preservation based on generalized preservation and user costs