1,721,018 research outputs found
Human element and design rules: state of the art
No full textBetween several transport systems one of the most used is the road, for the freedom that such modality guarantees to user, above all in case of good working. The relative statistics, concerning the phenomenon of the accident, attribute to the human factor the responsibility of beyond 83%. This last data has contributed to assume that, within the complex system "man-vehicle-infrastructure-environment", greater importance to the interaction "man-infrastructure", so towards the infrastructure characteristics, the dimension of the section, the visibility, the presence of different vehicles, the perception of the spaces, etc., influencing the control of the vehicle, from part of the users, in more or less favorable environmental conditions.
The road is the environment in which vehicles moves and with which the driver, through the vehicle, interacts. For this reason it is important that the environment transmits, to the user, clear marks, so that the corrected behaviour comes favourite.
Once the functions involved in the guide are defined it is necessary to find the role of these in the design. It is interesting to verify in that way and to that level, within the search and the normative systems, it is dealing with the relationship between technical choices and effects induced on the user. This work proposes to evidence actual state of the art regarding the role assumed from the user in the design, with reference to proposals from the wide panorama of research and of Italian, European and American normative system. The objective of the present article, that constitutes only the first phase of a wide research on the same topic, is to supply an outline of the situation of main design rules, inside of which, are considered the human elements
Sicurezza stradale. Rapporto tra ipotesi progettuali e dinamiche reali
No full textI dati pubblicati dall’Organizzazione Mondiale della
Sanità e dalla Commissione Europea rilevano che
annualmente gli incidenti stradali causano, a livello
mondiale, 1.2 milioni di morti e 50 milioni di feriti. A
fronte degli studi attribuenti al fattore umano
un’incidenza pari al 90 % e dei rilievi che riportano
l’esistenza di tratti stradali caratterizzati da elevati valori
dell’incidentalità, attribuendo, in tali casi, al fattore strada
un’incidenza del 30 %, è accresciuta l’attenzione sul
rapporto uomo-strada in riferimento alla sicurezza
stradale.
La ricerca nazionale ed internazionale al fine di ridurre i
valori dell’incidentalità, specie sulle strade extraurbane a
due corsie e carreggiata unica (ove si sviluppano la
maggior parte degli incidenti gravi), e quindi per
migliorare l’interazione uomo-ambiente stradale si rifà
alla design consistency. Uno degli elementi cardine di
ques’ultima è il concetto della velocità operativa, sulla
quale si basano le principali teorie della design
consistency. In Italia, come è noto, con il D.M. del 2001
sono entrate in vigore le nuove norme di progettazione
stradale, secondo le quali le principali caratteristiche
geometriche e di progetto dell’infrastruttura viaria sono
calcolate ancora in funzione della velocità di progetto. In
Sardegna, negli ultimi anni, sono stati aperti al traffico
diversi tratti di una strada extraurbana a carreggiata
unica e due corsie progettata nel rispetto del D.M.
5/11/2001.
L’obiettivo del presente articolo è verificare, su tale
strada, della quale sono note le principali caratteristiche
geometriche e di progetto, i principali modelli nazionali, e
qualche modello internazionale, redatti in riferimento
all’interazione tra conducente ed ambiente stradale.
La ricerca del Dipartimento di Ingegneria del Territorio
dell’Università di Cagliari è finalizzata, appunto,
all’implementazione di tali modelli finalizzata alla
redazione di riferimenti univoci, attendibili e accettabili a
livello nazionale
Gli interventi di riqualificazione e di adeguamento della rete viaria possono concorrere al recupero delle aree interne
No full textStatistical Analysis of V85 Models on Horizontal Curves of Italian Two-Lane Rural Roads
No full textInjuries are one of the main causes of death according to the new report published by WHO (World Health Organization). For this reason the attention of road safety research especially regards the study of the relationship between driver and road environment, in order to obtain a reduction of injuries number and severity.
Several studies were developed to find the relationships between road geometrical and design features and driver behaviour.
Generally driver behaviour is expressed by the operating speed. In scientific literature there exist several analytical models to calculate real speed as a function of geometrical road characteristics.
In this work some of them were collected and their hypotheses were studied. Generally the values of these parameters were similar in the majority of the models and they can be found in the Italian rural roads in order to make surveys.
The next step was the statistical analysis of the existing models with hypotheses that could be applied to Italian roads in order to define the best one
Studying Roundabout Performances Using Kriging Techniques
No full textGenerally road intersections are the most dangerous
places into the road space. This is mainly caused from the many
conflicting points existing in that road area. Generally
roundabout reduces considerably the number of conflicting points
with respect to a stop or yield intersection, from 32 to 8 conflicting
points. For this reason, in recent years, many countries have
adopted roundabouts as a design solution for both urban and
rural road intersections. This happens even if the available space
is not enough: for this reason, there are a lot of non-standard
roundabouts, for example with one of legs without deflection.
The absence of deflection can modify the roundabouts
performance. Roundabout works well if specific traffic and
geometric conditions exist. The parameter used to estimate if a
roundabout can work well or not is its capacity (where capacity is
defined as the maximum entering flow). One of more popular
method to investigate roundabout performances is based on the
relationship between entering flow (Qe) and circulating flow (Qc).
These models have been built by using statistical regressions and
only for well designed roundabouts.
The paper reports a different approach to the phenomenon: an
approach based on geostatistical theories, which consider the
relationship between Qe and Qc as a regionalized phenomenon.
According to this collected data are not random values but are
supposed to be related to each other with a defined law. The paper
analyzed both roundabouts with and without deflection
Relationship Between Sight Distance and Operating Speed on Horizontal Curves
No full textAll guidelines give more or less interesting and considerations about stopping and passing sight distances. Sight distance is the portion of the roadway available for view at any given time. In the Italian design guidelines sight distance is considered an important factor for road safety. It is the base for the calculation of design elements such as curve radii and vertical curvatures. The amount of available sight distance is considered of the utmost importance in the safe and efficient operation of vehicles on a highway.
The aim of the analysis is to investigate the relationship between the operating speed and the geometric features, into the studies of several countries, in order to create an operating speed model, where the V85 is expressed as a function of Curvature Change Rate of the single curve (CCRs) and available sight distance.
In the beginning of the article, the most important national and international models, which enable to calculate V85 in the Italian highways, are summed up.
Then speed surveys, varying the available sight distance, are carried out. Driving speed in the midpoint curves is evaluated. During surveys just passenger vehicles in free flow are included (headway of at least 5 seconds). Besides different constraints have been imposed to select curve sites: rural area, marked and paved roadways with constant lane width, no intersections near to curve, longitudinal grades ≤ 6%.
The research project, which is carried out by the Department of Land Engineering of the University of Cagliari, aims to develop an analytical model that permits to calculate V85 as a function of CCRs and available sight distance
Sustainability of Pedestrian Paths
No full textGenerally, when we talk about sustainability we think the main reference is the respect of the natural environment,
but the concept of sustainable road infrastructure may be even wider especially if you think the pedestrian paths, where
the concept of sustainability is closely linked to that of quality of the road. In this regard it is known that the quality of a
road is perceived differently by different users, whose behaviours vary according to the motivations of the
displacement, the length of the path to follow, the security and the comfort perceived. These differences are even more
pronounced in the case of pedestrians, for whom the concept of sustainability/quality of the path takes a key role, even
in just the choice of the same. When designing a pedestrian path, often it still refers to '"average user", ignoring the
great variability in the skills, abilities and knowledge that characterize the population that already moved or which in
fact see denied the possibility of moving.
This article analyzes the pedestrian behavior with specific attention to critical detectable along the existing
pedestrian routes especially for the mobility-impaired pedestrians, analyzing the difficulties of moving people with disabilities. In the first part of the article are briefly described the basic principles of Design for All and the characteristics of pedestrians in relation to age and motor skills, in order also to highlight how the concept of the
average user in the design of spaces pedestrian is obsolete. The second part analyzes the perception of the quality of pedestrian paths by pedestrian themselves, paying particular attention to those with reduced mobility. The work,
reported in this article, is the first part of a broader research work that sees the authors engaged with Psychologists,
Botanists and Architects, about the quality of the urban road
Study on Safe Way to School in Italy
No full textEvery year thousands of accidents which have occurred involving children aged between 2 and 14 years were recorded mainly on the way to school. The way to school is the first and most important approach for children with the use of urban space. The most evident response to the risk of road is provided by the parents' behavior: they go to school with their children. Last statistics have shown that in Italy on the urban road network accidents and injuries grow over 80% and a little less than 2/3 of deaths from road accidents. The described situation is heavy with pedestrian-vehicle conflicts, in which speed is the main factor in the severity of the accident, especially when children are involved.
Medical studies indicate that the increased exposure of children to the dangers of the road is related to their incomplete development compared to the standard features of the adult. Hence the need to plan safe way to school.
The paper is divided into the following parts:
• general overview of the urban area;
• construction and analysis of the O/D matrices on the paths of children;
• analysis of key issues and critical;
• explanation of proposed projects.
For the organization and planning of the ways to school we used a careful analysis of the interested areas and urban paths. When the school is located in residential neighborhoods, we verified, for example, the feasibility of a "30 zone”. In the outside of the “30 zone” we proposed several design solutions to lead the children towards school paying attention to crosswalks. Another solution that we considered was the creation of a “residential zone”, in which the car drivers give priority to the pedestrians and the motorized traffic is deterred. When the design of “30 zone” or “residential zone” was not possible, we designed the ways to school along urban roads. Another solution was the design of “restrict traffic zone” next to school, at least during time entry and exit of the children, so that there are not cars in front of school
Analysis of Horizontal Curves Operating Speed Models for Italian Two Lane Rural Roads
No full textThe scientific literature shows the existence of many studies about influences of road
features on driver behaviour. Most of researchers focused their attention on the building of
mathematical models that should be able to link driving behaviour and road characteristics.
Several international research works show that operating speed is an excellent driver
behaviour parameter. The road characteristics are represented by curvature change rate of
the single curve (CCRs) or by circular curve radius (R). In Italy two-lane rural roads can be
divided into two main categories: roads built before and after 2001. The main difference
between these two types is that the roads built before 2001 did not include transition curves.
A previous statistical analysis (that was carried out at the University of Cagliari, Italy) had
demonstrated that the existing international models are representative of driving behaviour
on the Italian roads built before 2001; but none of them is applicable to the roads that were
built after 2001. For this reason it was decided to proceed with the construction, on the basis
of speed data collected, of new models of driving behaviour in Italy. The work is divided into
four main steps:
1. construction of a model for roads built before 2001 (although some of the existing ones
are applicable to Italian two-lane rural roads, it was decided to construct an ad hoc
model because of the close correlation between the model itself and the context in which
it has been created);
2. construction of a valid model for the Italian roads built after 2001 (because none of the
existing ones is applicable to this type of road);
3. construction of a valid model for both types of roads (roads built before and after 2001);
4. in the conclusions, comparison between the obtained results and some existing
international models
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