1,721,270 research outputs found
Older drivers and safety: a roadway study using driving simulator
No full textThe population is aging all over the world and the proportion of seniors is increasing from 10 to 20 % of the
total population. The number of serious injuries due to crashes increases from about 50 crashes per billion
km for the age groups from 25 to 65 years old to more than 250 crashes per billion km for the older age
groups. The impact of older drivers on road safety is due predominantly to age-related impairments.
Considering the difficulties, both in gaining older drivers’ compliance with safety measures and in avoiding
difficult driving situations, and considering the limited effectiveness of additional in-vehicle devices, this
paper proposes to enhance the safety of the infrastructure for elderly people. Studies examining roadway
characteristics have mainly focused on intersections. Here, the roadway geometry has been analyzed. Two
stretches of a very hazardous road were simulated using an interactive driving simulator. Two age groups of
young and older drivers were tested. The speeds of younger and older drivers were compared along the
roadway. The understanding of the road was also assessed through a comparison of the two age groups. It
was found that, if the geometry of the roadway is complex and tortuous, the speeds of older subjects are
generally much lower than the speeds of younger subjects. The dispersion of speeds is always much greater
for older rather than for younger drivers. From the outcomes of this study, the self-understanding road is
expected to be self-understanding for both younger and older drivers, but at a different level. Younger
drivers make more correct manoeuvres than older drivers. This study concludes that the older drivers
experience more difficulties in understanding roadway geometry
Evaluating participatory practices, an inherent challenge for territorial development
Full text linkFil: Guardamagna, Melina. Consejo Nacional de Investigaciones Científicas y Técnicas. Universidad Nacional de Cuyo; Argentina.Fil: Benedetto, Andrea. Universidad Nacional de Cuyo; Argentina
ELeNA Evaluation of LEvel of Noise around Airport
No full textSoftware per la valutazione del rumore in ambito aeroportual
A decision support system for the safety of the airport runways. The case of the heavy rainstorms
No full textWater content evaluation in unsaturated soil using GPR signal analysis in the frequency domain
No full textThe evaluation of the water content of unsaturated soil is important for many applications, such as
environmental engineering, agriculture and soil science. This study is applied to pavement engineering, but
the proposed approach can be utilized in other applications as well. There are various techniques currently
available which measure the soil moisture content and some of these techniques are non-intrusive. Herein, a
new methodology is proposed that avoids several disadvantages of existing techniques. In this study,
ground-coupled Ground Penetrating Radar (GPR) techniques are used to non-destructively monitor the
volumetric water content. The signal is processed in the frequency domain; this method is based on Rayleigh
scattering according to the Fresnel theory. The scattering produces a non-linear frequency modulation of the
electromagnetic signal, where the modulation is a function of the water content. To test the proposed
method, five different types of soil were wetted in laboratory under controlled conditions and the samples
were analyzed using GPR. The GPR data were processed in the frequency domain, demonstrating a
correlation between the shift of the frequency spectrum of the radar signal and the moisture content. The
techniques also demonstrate the potential for detecting clay content in soils. This frequency domain
approach gives an innovative method that can be applied for an accurate and non-invasive estimation of the
water content of soils – particularly, in sub-asphalt aggregate layers – and assessing the bearing capacity and
efficacy of the pavement drainage layers. The main benefit of this method is that no preventive calibration is
needed
OPEN-GRADED ASPHALT MIXES: HYDRAULIC PERMEABILITY AND MECHANICAL CHARACTERISTICS
No full textSkid and hydroplaning induced by water film on pavement are critical problems for road safety.
Porous pavements are considered to potentially be effective solutions. A new low cost and user friendly piece of
equipment for measurement of Darcy hydraulic permeability of pavement is presented in this study. The
reliability and repeatability of measurements have been verified. The main points used to verify the strength of
the equipment, recently patented in Italy, follow: (i) the measurement is developed before pavement construction
in the laboratory and it is possible to optimize the mix design, (ii) Marshall samples were used for hydraulic
measurements, unless destruction or perturbation was necessary, for subsequent mechanical testing, (iii) standard
cores extracted from existing pavement can be inserted into the instrument to measure the current hydraulic
permeability, (iv) the equipment measures permeability, assuming homogeneity and isotropy as a hypotheses, (v)
the equipment is low in cost, both for materials and for technology, (vi) no electric or other power is needed, it
works under hydraulic load, (vii) the equipment works both at constant and at variable hydraulic load. Finally,
the experimental outcomes of a research project are discussed, in order to assess the correlation between the
hydraulic permeability of pavement and bitumen content, which voids percentage and aggregate grading. Very
cautious standards for mix design are imposed in order to have adequate permeability, and this is validated after
pavement development. The final permeability obtained respecting those standards is always higher than the
needed one. It induces relevant economic and environmental costs. After verifying in the laboratory the
hydraulic permeability and the mechanical resistances of the 24 pavement samples, the effectiveness of an
experimental procedure for the optimization of the mix in terms of hydraulic and mechanical standards has been
assessed. Outcomes show that permeability always decreases if Young’s Modulus increases. Aggregate grading
influences this relationship and the procedure of making of samples influences the mechanical and hydraulic
final characteristics. Relevant economic and environmental benefits are a reasonable expectation
A three dimensional approach for tracking cracks in bridges using GPR
No full textCorrosion associated with reinforcing bars is the most significant contributor to bridge deficiencies. The corrosion is usually caused by moisture and chloride ion exposure. The reinforcing bars are attacked by corrosion and yield expansive corrosion products. These oxidation products occupy a larger volume than the original intact steel and internal expansive stresses lead to cracking and debonding. There are some conventional inspection methods for the detection of the reinforcing bar's corrosion but they can be invasive and destructive, often laborious, and lane closure is required and it is difficult or unreliable for any quantification of corrosion. For these reasons, bridge engineers always prefer more to use the ground penetrating radar (GPR) technique. In this work a novel numerical approach for three dimensional tracking and mapping of cracks in the bridge is proposed. The work starts from some interesting results based on the use of the 3D imaging technique in order to improve the potentiality of the GPR to detect voids, cracks or buried objects. The numerical approach has been tested on data acquired on a bridge by using a pulse GPR system specifically designed for bridge deck and pavement inspection. The equipment integrates two arrays of Ultra Wide Band ground coupled antennas, having a main working frequency of 2. GHz. The two arrays are using antennas arranged with a different polarization. The cracks, associated often to moisture increase and higher values of the dielectric constant, produce a not negligible increase of the signal amplitude. Following this, the algorithm, organized in preprocessing, processing and postprocessing stages, analyzes the signal by comparing the value of the amplitude all over the domain of the radar sca
- …
