659 research outputs found
Compensation effect between deaths from Covid-19 and crashes: The Italian case
No full textEmergencies such as the Covid-19 pandemic pose several decision-making issues, while clear evidence of successful strategies are still unavailable, different policies may be identified. However, in such emergencies, the preservation of public health, by firstly reducing human loss of life may be prioritized and then restrictive measures are implemented. The trade-off between damage due to the threat and the decrease in damage due to the lockdown is largely unexplored. Here we show that there is a degree of compensation between damage from epidemic deaths and from traffic deaths, especially in the case of immediate restrictive measures imposed by governments. Based on the Italian case, we found that damage from loss of human Capital and health care costs could have been fully compensated if the lockdown had been imposed ten days earlier. Considering only one Italian region (Puglia), where the epidemic was delayed and then restrictions were timely, damage due to loss of human Capital was largely compensated in the real scenario. However, damage due to loss of welfare could not have been fully compensated for, since Covid-19 deaths largely outnumber traffic deaths in the simulated epidemic period and loss of welfare damage is scarcely dependent on the age-at-death. From a broader perspective, societies seem to react to external threats as a whole organism, thus tending to restore the original equilibrium. Governmental decisions could accelerate this process. However, in the case of similar threats, some wounds cannot be compensated for, such as the incalculable damage due to loss of welfare
Connecting Rural Road Design to Automated Vehicles: The Concept of Safe Speed to Overcome Human Errors
No full textThe human-road-vehicle automated system is a challenge to overcome human errors. Several rural road crashes happen due to loss of friction, unlikely predictable by drivers. The friction diagram method (FDM) by the authors, described in previous papers, is able to evaluate the skidding risk taking into account vehicle, environmental, road factors. An important variable is the vehicle speed. According to the FDM, the speed corresponding to the maximum friction used can be computed. If all vehicles will travel at speeds lower than that, all other safety checks being verified, then the skidding risk can be reduced. Automated vehicles could travel at the safe speed predicted for each section, by acquiring all the necessary information directly from the road. The algorithm can be customized according to the particular vehicle, tires and road conditions. Additional remarks about the shift from traditional road design practice to the driving automation are also given
The deviation angle for one-lane roundabouts: A general mathematical formulation and application
No full textProperly designed roundabouts may lead to safety improvements based on both reducing approaching speeds and controlling traffic. Measurements of deflection of vehicle trajectories are commonly used to estimate roundabout speed control. One of these measurements is the deviation angle, which is mentioned in both the Italian and Swiss road standards and, in specific conditions, can be more effective than other methods. This article presents a general mathematical formulation for linking several geometric parameters with the deviation angle in different rural and urban one-lane roundabout configurations, which is currently missing in the literature. For urban roundabouts, refuge islands for pedestrians and cyclists were considered. Based on the proposed formulation, a sensitivity analysis of the influential geometric parameters was conducted. Results suggest that an insufficient deflection of trajectories (deviation angle less than 45°) is always present for roundabouts with inscribed circle diameter less than 25 m; for urban roundabouts with refuge islands for pedestrians and cyclists having inscribed circle diameter less than 34 m and orthogonal legs; and for roundabouts with angles between opposite legs smaller than 140°. The main parameters which are responsible for a decrease in the deviation angle are: a decrease in the inscribed circle diameter; a decrease in the angle between opposite legs; and an increase in the width of the circulatory lane. Some optimized procedures for roundabout design, the generalized application of the deviation angle method and alternative speed control measures in cases of small deviation angles are discussed
Route familiarity in road safety: A literature review and an identification proposal
No full textRoute familiarity can be an important safety-related variable, which is often neglected. A review of previous works highlighting the relationships between route familiarity and road safety in behavioural studies and engineering standards/frameworks has been conducted. Theoretical frameworks supported by experimental results have revealed that driving behaviour can be affected by route familiarity. The latter may lead to distraction and self-confidence; and in turn to more dangerous behaviours after repeated journeys. From an economic perspective, the possible worsening of driving safety performance may be explained by trade-offs with mobility benefits. Route familiarity is also considered in engineering practice. Road design guidelines assuming a “design driver” were suggested as implicitly preserving the safety of familiar/unfamiliar drivers. The mix of familiar and unfamiliar drivers in traffic flow is explicitly considered when computing the design traffic. The safety implications of these matters find only partial confirmation in previous studies focused on involvement in crashes. However, comparing those findings was difficult due to the high variability in measuring the route familiarity itself. An attempt to harmonize the possible identifications of familiarity for future studies, based on previous findings, is proposed. The proposal considers two different scales used for measuring route familiarity: one based on travelling frequency, the other on distance from residence
The influence of memory on driving behavior: How route familiarity is related to speed choice. An on-road study
No full textDifferences in driving behavior due to the presence of users familiar (or unfamiliar) with the road are considered in the road and traffic engineering. However, although considered, the matter is largely unexplored: there is a lack of theoretical foundations and data on determining the impact of route familiarity on accident rates, speed choice and risk perception. On the other hand, some literature studies confirm that route familiarity is influential on driving behavior, encouraging research in this sense.This paper reports the results of an on-road test carried out on a two lane rural road in the District of Bari in the Puglia Region (Italy) over six days of testing by following this time schedule: first four tests in four consecutive days, the fifth test in the ninth day after the first test and the sixth test in the twenty-sixth day after the first test. The main aim of the experiment was to find relationships between route familiarity and speed choice. In particular, speed data were analyzed by considering the influence of road geometry and human factors.The main finding is that speed choice seems to be affected by route familiarity: speed increases with the repetition of travels on the same route. The particular schedule used for the tests allows to consider the influence of memory on the speed behavior of the test drivers. Moreover, some relationships between changes in speed over days, road geometry and drivers' attitudes were shown
Geometric Design Issues and Safety Analysis of Two-way Rural Road Tunnels
No full textRural road tunnels may pose specific issues from several perspectives: mainly environmental, geotechnical/structural (excavation methods), economical. Geometric road design is then an often arduous task, which should be conducted by trying to make trade-offs between the different issues, and at the same time, it should be compliant to relevant standards and regulations. Nevertheless, the safety of road tunnels should be preserved, not only considering technological systems (e.g. ventilation systems, emergency exits and paths), but also regarding traditional road-safety issues related to road geometric features. In fact, the analysis of recent accident data related to two-way two-lane rural road tunnels has revealed that accident frequencies/rates in two-way two-lane rural road tunnels are comparable with those on the corresponding open sections, even with some differences concerning the accident types. Since road safety issues may be exacerbated by geometric design inaccuracies, some relevant road tunnel geometric issues are discussed in this study. These issues, scarcely treated in previous research and not addressed in detail in technical documents, emerge from the match between different design needs. In detail, those relate to: 1) the possible need for variable road tunnel cross-sections in case of lane/shoulder widenings for the sake of improving visibility or for other reasons, or in case of lay-bys, 2) the possible need for climbing/overtaking lanes in case of steep downhill or uphill slopes. An attempt at addressing the mentioned problems is provided, based on relevant existing research and technical documents. In particular, the preliminary design stages leading to a "WES" (Without Enlargement Solution) solution are described. Hence, besides enlarging the research body in this specific field, the study is also potentially deemed useful for practitioners who have to face similar design problems
Integrated American-European protocol for safety interventions on existing two-lane rural roads
No full textThe main purpose was to integrate two strategies for road safety analyses (qualitative: audits, inspections; and quantitative: accident predictions) and develop a possible protocol for the safety interventions on existing two-lane rural road segments. Those road sections do not typically belong to the TEN-network, to which the 2008/96/EC Directive is mainly oriented. Hence, they could lack of methods for designing safety-based interventions. The main research questions were: Which possible problems can arise from the application of this protocol to real cases? Which data are practically needed? Which possible solutions can be provided for the highlighted problems? The integrated protocol, including: 1) the HSM predictive method, 2) the EU Regulations, 3) the local road design standards, 4) some research developments; is applied to real two-lane rural road segments requiring safety-based interventions. Its application is divided in the typical road safety analysis stages. A wide list of possible problems was highlighted and addressed: 1) lack of data, 2) difficult comparison with current road standards in order to identify safety problems, 3) lack of methods for evaluating the skidding risk along the layout, 4) setting speed limits, 5) need for optimizing the selection of countermeasures based on their aims and their timely application, in different recurrent situations, 6) availability and comparison of predictive methods. Based on the problems and solutions discussed, main advantages (1) the systematic approach, 2) the quantitative assessment of benefits, 3) the possible transferability) and disadvantages (difficulties in overcoming the lack of data and calibrated accident prediction models) of the method were remarked
The role of route familiarity in driving behaviour
No full textDifferences in driving behaviour due to the presence of users familiar (or
unfamiliar) with the road are considered in the Highway Capacity Manual (HCM)
procedure used to evaluate the level of service of Freeways and Highways. However,
although considered, the matter is largely unexplored: there is a lack of theoretical
foundations and data on determining the impact of route familiarity on accident
rates, speed choice and risk perception. On the other hand, some literature studies
confirm that route familiarity is influential on driving behavior, encouraging research
in this sense. In this paper, the authors propose some possible relationships between
route familiarity and road safety by considering an experiment carried out on a two
lane rural road and, in particular, by analysing how the habit of driving on a given
route could be influential in speed choice, risk perception and, potentially, on
accident rates too
Investigating the Deviation Angle Method for Ensuring Deflection at One-Lane Rural Roundabouts
No full textRoundabouts developed as a road intersection design option has resulted in a series of nonuniform design guidance criteria in Europe, as well as in the United States and other Countries. In addition to different design specifications about the geometry of the elements constituting a roundabout (width and lanes of the circulatory roadway, entry and exit legs, splitter island), the methods for guaranteeing that vehicle paths deflect through the roundabout are also different. These methods ensure proper travel speeds between conflicting traffic flows. Currently, the main parameters used by standards to control the deflection are the deflection radius, the entry path radius, and the deviation angle. After a comparison between International deflection methods for roundabouts, this study checks the geometric requirements of the deviation angle for more than 7.000 hypothetical one-lane rural roundabouts. The Computer-Aided Design (CAD) drawing of the roundabouts takes into account the range of variability of their main geometric parameters, according to the Italian Standard. Subsequently, a number of the considered roundabouts checked with both the entry path radius and the German methods. Some results showing the greater effectiveness of the less popular deviation angle method are discussed. The main aims of this paper are:1) to promote the deviation angle method, which is only used in Switzerland and Italy;2) to improve standards, as regards the applicability and validity of the deflection angle method;3) to help practitioners to know in advance the outcome of the deflection checks at the beginning of the iterative design process, once the boundary conditions are known
Geometric and Operational Features of Horizontal Curves with Specific Regard to Skidding Proneness
No full text(1) Run-off-road (ROR) crashes are a crucial issue worldwide, resulting in a disproportionate number of traffic deaths. In safety research, macro-level analysis on large datasets is usually conducted by linking explanatory variables to ROR crash frequency/severity. Micro-analysis approaches, like the one used in this study, are instead less frequent. (2) A comprehensive Italian Fatal + Injury (FI) crash dataset was filtered to identify two-way two-lane rural road curves on the national road network on which more than one ROR FI crash (i.e., at least two crashes) in the observation period of four years had occurred. The typical features of the ROR FI crashes and the recurrent geometric (characteristics of tangents and curves) and operational features (inferred speeds, acceleration/decelerations) of the crash sites were reconstructed. (3) The main contributory factors in ROR FI crashes are: wet pavements, speeding, and distraction. Sites with a relevant history of ROR FI crashes present recurrent safety issues such as inadequate horizontal curve coordination, an insufficient tangent length for decelerating, and inferred operating speeds comparable/higher than the inferred design speeds. (4) Based on findings, some practical suggestions for road safety management and maintenance are proposed through specific indicators and countermeasures (speed, perception, and friction related)
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