Giuseppe Loprencipe

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.

Rail roughness and rolling noise in tramways

Companies which manage railway networks have to cope continually with the problem of operating safety and maintenance intervention issues related to rail surface irregularities. A lot of experience has been gained in recent years in railway applications but the case of tramways is quite different; in this field there are no specific criteria to define any intervention on rail surface restoration. This paper shows measurements carried out on some stretches of a tram network with the CAT equipment (Corrugation Analysis Trolley) for the principal purpose of detecting different states of degradation of the rails and identifying a level of deterioration to be associated with the need for maintenance through rail grinding. The measured roughness is used as an input parameter into prediction models for both rolling noise and ground vibration to show the potential effect that high levels of roughness can have in urban environment. Rolling noise predictions are also compared with noise measurements to illustrate the applicability of the modelling approach. Particular attention is given to the way the contact filter needs to be modelled in the specific case of trams that generally operate at low speed. Finally an empirical approach to assess vibration levels in buildings is presented.

Comparison of methods for evaluating airport pavement roughness

ABSTRACT The correct and timely assessment of the airport pavements surface quality is fundamental to verify the presence of any irregularities that could be detrimental to aircraft operations. Furthermore, a rough runway can increase the maintenance costs of both pavements and aircrafts landing gears, due to the increment of dynamic loads and fatigue phenomena on airplanes structural elements, reducing their service life. Nowadays, the maintenance budget available by airport agencies is very restricted, thus, it is necessary to define properly the type and the extension of interventions able to restore runway evenness. In this paper, the roughness assessment of real runway profiles is carried out using first of all BBI and IRI but also ProFAA simulation model, with particular attention to Cockpit Vertical Accelerations, underling the different impact on airport pavement management of the results provided by them. In particular, very low correlations for the whole sample of examined profiles were found between IRI and BBI (R 2 = 0.11) and between IRI and cockpit vertical acceleration (R 2 = 0.03), while a better correlation was obtained between BBI and cockpit vertical acceleration (R 2 = 0.59). Neglecting runway profiles characterised by long wavelengths roughness, a very high correlation between IRI and BBI (R 2 = 0.91) was found, that underlines their different sensitivity to long wavelengths. In particular, it was found that for roughness characterised by low wavelengths, the IRI method seems to be more conservative than BBI. In addition, two different IRI acceptance thresholds were taken into account, one used in South Africa (2 m/km) and one adopted in Canada (2.7 m/km). For the whole profiles sample, little differences were found in their runway sections evaluation (about 4%) compared to BBI method; while, considering the reduced sample where profiles characterised by long wavelengths roughness were excluded, the use of IRI limit of 2 m/km would seem to be too conservative.