PAVEMENT MAINTENANCE SERIES – ARTICLE 1
This first article sets the scene for the evolution of roads, the need for maintenance, and introduces the engineering science behind pavement maintenance.
Ancient people began to open paths as a way to discover new fields, increase their territory, and also for religious ceremonies. These paths didn’t have a specific treatment and, therefore, the water infiltrated the soil due to the rain caused deformations in the subgrade, that is, in short periods of time, it was necessary to build these paths again.
The Romans were responsible for improving road construction because they saw that was required a structure with load resistance, which didn’t allow water infiltration, but also needed periodic care so that the road was always in good condition. For hundreds of years after the fall of the Roman Empire, these paved roads were still the best travel route across Europe, the Middle East, and North Africa.
Pavement Maintenance:
Today in engineering the maintenance is a well-established concept, although in some places its use is more similar to that ancient people, that is, they do maintenance only when the road is in bad condition. In paving, maintenance and conservation activities go far beyond the costs of just the road itself.
A road with irregular pavement, excess cracks or corrugations and patch for example, also affects the costs involved in the operations of vehicles. A car or truck driving along a road under these conditions requires the driver to take frequent acceleration and slowdown actions and impact on fuel consumption.
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Furthermore, depending on the severity level of pavement defects, this lack of maintenance can impact the costs involved in vehicle maintenance, such as damage to a vehicle’s suspension.
How does the lack of maintenance affect pavements today?
Pavement maintenance can be related to a term called serviceability, which was proposed still in the AASHO Road test and helps to understand how the time or traffic impacts in the pavement performance. Serviceability measured in a given period of time how this structure serves the driver for the 3 purposes for which it is intended (structural capacity, rolling comfort and safety).
This evaluation is divided into values from 0 to 5 according to a level of criteria. The maximum serviceability value indicates a pavement in perfect conditions, and the minimum value is that pavement that presents so many distresses that it doesn’t fulfil its purpose anymore. The table below illustrates a scenario of pavement deterioration over time and possible maintenance activities.
Reference: Hicks, G. R. et al (1999)
Through the figure, we can see that when the pavement reaches a serviceability value of approximately 3 (60% of the initial value and fair in the diagram), the costs for maintenance for rejuvenation is low. However, for a serviceability value of 20% of the initial value, the costs for the same activity increases by 5 times. Furthermore, it is also interesting to note that the time interval between them is approximately 12% of the structure life cycle, that is, in a short period of time costs grow exponentially.
Would you like to understand more about pavement maintenance activities? We will approach this in the next article in this series.
REFERENCES:
Hicks, R.G. & Moulthrop, James & Daleiden, Jerry. (1999). Selecting a Preventive Maintenance Treatment for Flexible Pavements. Transportation Research Record: Journal of the Transportation Research Board.
BALBO, José Tadeu, “PAVIMENTAÇÃO ASFÁLTICA: Materiais, projeto e restauração”. São Paulo, 2007.
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