1,721,171 research outputs found
Appunti del corso di Tecnica ed organizzazione del cantiere. Parte I: Il Quadro Normativo e Legislativo
No full textAppunti del corso di Tecnica ed organizzazione del cantiere. Parte II: I Materiali ed i Processi Costruttivi
No full textAppunti del corso di Tecnica ed organizzazione del cantiere. Parte III: Il Progetto del Cantiere: gli Impianti, le Opere Provvisionali, le Attrezzature e le Macchine
No full textIntegrated performance indicator in urban road infrastructure management
No full textThe management of the road sector today is based on goals and results. In urban areas goals are defined in the transport policy set by local government, and the most common objectives in these policies are: accessibility for all users (i.e. vehicles, pedestrian cycle, etc.), safety, environment, transport quality and mobility, asset development and improvement.
Decision support system ought to be used for defining and prioritizing different maintenance/improvement activities, in order to ensure the fulfilment of the pre-defined goals. These processes are based on indicators, which measure the effectiveness of the maintenance activities respect to the pre-defined objectives. As matter of fact substantial efforts have been made to define and develop suitable and relevant performance indicators in the past decade.
In this study the lessons learned from this findings are used in order to develop a set of performance indicators for management of urban road pavement. An holistic approach is used in developing the framework of indicators, that is hierarchical (articulated in three levels), fully integrated (conversion from technical to key indicators), target oriented (fits the specific target that needs to be measured), and based on measured road attributes. The present paper illustrates the overall framework focusing on methods and criteria used in the development of environmental indicators dealing with relevant issues such as traffic induced noise and vibration. A case study is also presented in order to demonstrate the effectiveness of the framework proposed
Analysis of the porous asphalt viscoelastic behaviour
No full textIn the latest years porous asphalt concrete has been largely used as it reduces the noise and avoids aquaplaning phenomena.
The use of modified bitumen has allowed to obtain porous asphalts with remarkable mechanical characteristics.
Therefore, it can be useful to carry out a right characterization of porous asphalt, starting from the evaluation of a reliable complex modulus under both performance and provisional regard. After this, we can
examine the representative rheological model and finally study the resistance to fatigue and rutting.
The mix asphalt mechanical behaviour is normally characterized by using the components of complex modulus: absolute value and phase angle. These components are both important for a right analysis of pavement performances.
In the first part of this work we realized a study about the
applicability of the test method EN 12697-26 to porous asphalts. An extensive campaign of tests (four point bending test) was carried out, at different temperatures and frequencies.
We analyzed:
1. The measure repeatability and the numerousness of the sample, in order to obtain a reliable complex modulus characterization in both absolute value and
phase angle for a fixed error;
2. The linear behaviour and the stiffness modulus variability with the strain, in order to choose the test conditions (referred to in situ strain conditions);
3. The influence of compaction variability on the complex modulus, in order to give directions about the specimen preparation.
In the second part of the work the adaptability of the predictive formula proposed by Witczak et al. for the stiffness modulus and of the rheological models more in
use was evaluated
An exploratory step for a general unified approach to labelling of road surface and tyre wet friction
No full textWet skid-resistance is of paramount importance for road safety as it has been recognized to affect wet-road accidents. Recently European Regulations are introducing mandatory classification for tyre friction performance by means of tyre labelling procedure. In this paper an experimental study has been carried out in order to search for a relationship between indexes employed in the tyre and pavement classification. Coupled friction tests have been performed in a controlled manner on five test track with varying texture properties and significant statistical relationship has been derived between Wet Grip Index (WGI), as defined in the European Tyre Labelling Procedure and the International Friction Index (IFI), according to World Road Association (PIARC) friction harmonization experiment. If a temperature correction of skid data is applied a good correlation between WGI and IFI can be obtained. Although the experimental study has to be integrated with a wider measurement campaign, preliminary results seem to indicate that a unified wet tyre-road classification can be pursued allowing a better awareness of the road safety level among road users
Multi-Objective Approaches to Cross-Asset Resource Allocation in Transportation Asset Management
No full textPredicting roughness progression of asphalt pavements by empirical-mechanistic model
No full textThe evaluation of road roughness progression represents one of the most important issue of modern pavement design and management. The roughness deterioration models developed so far, are often based on an empirical approach. Usually, an extensive long-term measurement campaign on a wide range of pavement sections is needed to calibrate such complex regression models and additional difficulties occur in collecting data on overlay roughness evolution. Furthermore, empirical models are unable to take into account new pavement materials performance. Empirical-mechanistic approach could partly solve these problems allowing the development of deterioration models by numerical simulations.
In this paper an empirical-mechanistic model, implemented in a computer software, is described in order to simulate the progression of pavement roughness as function of loads, climate, structural configuration, overall construction quality and material properties. The analysis is performed by dividing the road section into 0.250.33 m long sub-sections. Material properties and layer thickness are assigned to the sub-section through a autoregressive process and non linear elastic behaviour of granular materials is taken into account. The simulation is performed through an iterative process according to which, within each computational step, the program calculates pavement stress-strain level and permanent deformation induced by dynamic loads, for 16 different types of axes and 8 daily climatic condition in each sub-section. At the end of step the total rutting is computed in each sub-section, the profile is updated and the IRI index of the road section is evaluated. The model has been used to simulate roughness progression and a preliminary parametric analysis has been performed whose results are briefly illustrated
Progetto degli interventi di manutenzione strutturale delle pavimentazioni stradali flessibili e semi-rigide
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