Giuseppe Cantisani

Road Roughness and Whole Body Vibration: Evaluation Tools and Comfort Limits

An important element of achieving quality in a road network is the control of vehicle vibration due to pavement roughness and road irregularities. Scientific literature and international standards suggest that we evaluate these phenomena by measuring the whole body vibration (WBV) on the road user, but, for the practical aims of road engineering, this expression has to be related to road unevenness indexes, especially the most common one (the international roughness index, IRI). This index, in turn, is obtained from measured pavement geometric data using a conventional model of a mechanical system representing part of a vehicle. To better investigate the problem of user comfort, more complex models and analyses are needed. In this paper, a model of a real and common vehicle is presented and used, after a calibration process, to perform many dynamic simulations. The obtained results, in terms of weighted vertical acceleration ( aWZ , that is, the WBV index, according to ISO standard), show good correlation...

The integrated design of urban road intersections: A case study

The design of urban road intersections always requires many activities, in order to analyse the technical aims of the project, as well as the environmental and architectural context. The choice of the optimal solution should be the result of a complex, well organised and optimized process. Updated techniques, devices and software are available nowadays, to integrate all the involved aspects. The proposed case study concerns an urban road intersection in the territory of Orte (VT, Italy), whose best geometrical and functional design solution has been defined using various tools, which mainly allow: (1) the three-dimensional geometrical modeling of the layout and road elements; (2) visualization, also with dynamic scenes; (3) functional analysis of traffic flows (traffic micro-simulation techniques).

Improvement of portable concrete barrier design using computational mechanics

Concrete safety barriers have been employed broadly in Italy since the 1980s, particularly on highways and freeways. Safety barrier homologation and design standards have not yet precisely determined specific fields of application or modality of installation, in particular for concrete barriers. Such barriers have sometimes been judged too rigid and, therefore, inadequate to pass crash tests conducted with lightweight vehicles. No changes have been made nor have new designs (crosssection shape and size) been developed in the past 20 years. For all those reasons, the possibility of achieving better overall performance with concrete barriers has been investigated (containment of heavy vehicles and lower accelerations on occupants of lightweight vehicles). One design proposal for these modular systems is to use lightweight concrete and make the element shorter than the one that is usually adopted in Italy. In that way, the higher lateral deformability of the barrier could lead to a greater dissipation of ene...

Reliance of pavement texture characteristics on mix-design and compaction process

The surface texture in Hot Mix Asphalt (HMA) pavements has an important role respect to all functional performances: wet and dry friction, rolling noise generation, tire wear, and so on. The texture of a new pavement is a consequence of HMA composition (mix-design) and of construction techniques, especially considering the compaction process. While numerous studies have investigated the effect of mix design on texture, it is still unclear the effect of construction techniques. In this research, some experimental results coming from on-site investigations during the HMA construction, were processed, in order to determine the texture characteristics of pavement surfaces, in terms of mega, macro and micro-texture, using both volumetric and profilometric measures. Furthermore, the asphalt mix composition (grain size, void ratio, bulk density, percentage of bitumen, etc.) were assessed on pavement cores. Some statistical correlations between texture and asphalt mix composition were also carried out. The results confirm that the main influence on the pavement texture level is related to the aggregate maximum dimension, but also the void percentage has a significant influence. The compaction conditions, instead, seem to determine a lower effect, but nevertheless some observations can be deducted. More general, the presented research proposes some considerations, useful to improve the design of mixtures and the compaction techniques of HMA, especially in order to obtain a reduction of rolling noise generation.

Retrofit of an Existing Italian Bridge Rail for H4a Containment Level Using Simulation

This paper describes the methodology for the development of a crashworthy heavy containment bridge rail for the Italian Highway System. The current design was determined to be inadequate for heavy vehicle containment and could not be demolished due to damage risk to bridge superstructure. Italian Highway Agency has decided to retrofit the current design. Two different bridge rail models are developed and analysed using 30 ton heavy vehicle according to European EN1317 Test TB71 requirements. Detailed finite element analyses are performed to evaluate the acceptability of retrofit alternatives. A versatile, highly non-linear and widely accepted finite element program LS-DYNA is used to simulate the crash events. Analysis results show that the final bridge rail model successfully contains and redirects the 30 ton vehicle and it is found to be an acceptable retrofit to existing bridge rail design. A full-scale crash test is recommended to substantiate simulation findings.

New research opportunities for roadside safety barriers improvement

Among the major topics regarding the protection of roads, restraint systems still represent a big opportunity in order to increase safety performances. When accidents happen, in fact, the infrastructure can substantially contribute to the reduction of consequences if its marginal spaces are well designed and/or effective restraint systems are installed there. Nevertheless, basic concepts and technology of road safety barriers have not significantly changed for the last two decades. The paper proposes a new approach to the study aimed to define possible enhancements of restraint safety systems performances, by using new materials and defining innovative design principles. In particular, roadside systems can be developed with regard to vehicle-barrier interaction, vehicle-oriented design (included low-mass and extremely low-mass vehicles), traffic suitability, user protection, working width reduction. In addition, thanks to sensors embedded into the barriers, it is also expected to deal with new challenges related to the guidance of automatic vehicles and I2V communication.