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This paper presents part of the studies developed in the European project ENSEMBLE. (ENabling SafE Multi-Brand pLatooning for Europe). The first part of the paper describes the validation of a numerical model based on comparisons with experimental results obtained from a test section subjected to the pass of 3 human-driven trucks simulating a platoon configuration. The numerical model is then used to predict the maximum and accumulated strains produced by the passage of each truck on the same test section at two different temperatures when the following platoon parameters are varied: (1) inter-truck time gap, (2) truck speed and (3) lateral deviation (wandering). The results confirm that the proper control of these parameters can help to keep the same level of fatigue damage as with trucks in individual configurations. In this way, the environmental, social and economic benefits of platooning can be attained without compromising the existing pavement structures. [ABSTRACT FROM AUTHOR]

The objective of this study is to assess the impact of climate on the performance of bituminous pavements with two different methods, and then to examine their impact on actual design scenarios. Three climate cases were selected for the comparisons involving the effect of temperature: one in France (Bordeaux) and two in the United States (Seattle and Phoenix). The case of an experimental site in Québec was also used for comparisons concerning consideration for seasonal variations in ground bearing capacity. The analyses were based on French (Alizé-LCPC) and US (AASHTOWare Pavement ME Design) mechanistic-empirical pavement design approaches. Interesting features of the two design methods are outlined and their fatigue cracking models are linked together. The results of the study highlight the importance, for design purposes, of the empirical fatigue equations as a function of temperature. For the site studied in France, the design results in terms of AC base layer thicknesses indicate that both methods show a similar trend with an increase in temperature. For the site in Québec, which is submitted to severe freeze/thaw cycles, the results show that taking temperature and moisture into account for unbound materials leads to a prediction of more severe permanent deformation. Highlights Presentation of two mechanistic-empirical (ME) methods for pavement design Description of the fatigue equations governing asphalt mixes for design purposes Identification of the parameters used in the design of pavement structures Study of the influence of the climate in France and Québec on pavement performance Comparison of the French and US methods for pavement design and correspondence between them [ABSTRACT FROM AUTHOR]

• Continuous behavior of HSL with bituminous sub-layer over 4-years was observed. • The bituminous sub-layer reduces acceleration levels under the ballast even after 4 years of service. • No fatigue damage was caused in the bituminous sub-layer under high-speed train traffic. • This study underlines the very good overall behavior of the track. • Detection of track damage using accelerometers appears possible. Tamping and ballast wear, due to dynamic stresses, lead to frequent and costly maintenance operations. To mitigate the impact, an innovative track structure combining a bituminous (asphalt concrete) layer below the ballast has been built on the Bretagne-Pays de la Loire High-Speed Line (BPL HSL). The track is intended to reduce the amplitude of the accelerations produced by passing High-Speed Trains (HST) which are the main reason for the settlement of ballast. BPL HSL includes 105 km of asphalt concrete sub-layer below the ballast and 77 km of granular sub-layer. In order to study the dynamic responses of these different structures, some track sections have been instrumented with anchored deflectometers, accelerometers, strain gauges and temperature probes. The aim of this paper is to present the results achieved after four years of commercial traffic. The data processing methods developed for this acquisition phase and the measurements of the substructure deflection, the vertical accelerations under ballast, and the vertical and horizontal strain of the various sections were presented. Deflection measurements, vertical strains and vertical accelerations peaks at the top of the sub-layer are compared between the granular and the bituminous track structures and shows that there is no evolution of the measurements during the four years of monitoring. The study clearly demonstrated that the presence of the bituminous layer in the structure reduces the acceleration levels under the ballast that cause its deterioration. Such conclusions suggest that a bituminous sub-layer might contribute to lower track maintenance needs over the service life of the line, decreasing operational costs and increasing capacity. [ABSTRACT FROM AUTHOR]