Abstract
Given their environmental impact, the careful design of asphalt pavements is crucial. Previous research has highlighted the influence of several parameters on the outputs of different pavement design methods. In this study, the focus is on heavy vehicle trends, considering both the percentage of heavy vehicles in the average traffic flow and its evolution over time, which is usually included as a growth factor in the design inputs. Since these factors are very often assumed to be based on old estimates, the first aim of this study was to update them by exploring a recent series of continuous data collected on the Italian motorway network and showing how to infer estimates from historical traffic data. Subsequently, the variability of these input factors is introduced in standard pavement design methods to assess their influence on the design process and to quantify the risk of overdesign. While the analysis of historical heavy vehicle traffic data may reveal an overall zero-growth traffic tendency, different scenarios should be considered and assessed in cost-benefit analyses given the not negligible influence of growth factors on pavement thicknesses. This influence is shown here in different simulated design conditions, with different initial traffic volumes, share of heavy vehicles, and resilient moduli.
Highlights
The construction of asphalt pavement systems has a strong impact on the environment
This study was conceived in order to answer some research questions which may be of interest for both practitioners and for the further development of research
It was aimed at assessing the relationships between heavy vehicle historical continuous traffic volumes and the related estimates useful for pavement design
Summary
The construction of asphalt pavement systems has a strong impact on the environment. Different approaches to improve the sustainability of road pavement systems have been proposed based on modified asphalts, recycling, life-cycle assessments, and optimized maintenance plans [1,2,3,4,5]. Independently of the type of pavement system, there are several uncertainties in the design process which may result in inappropriately determining the thickness of pavement layers. Whilst considering traditional asphalt pavement systems, a possible disproportionate thickness resulting from overdesign is a potential source of environmental damage. Careful design of road pavement systems may prevent squandering of resources. Different methods can be used for designing road pavement systems. As a result of the sensitivity analyses, the important role of some factors was highlighted (for example, the determination of the subgrade resilient modulus, see [10])
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