Valerio Veraldi

Investigating the influence of highway traffic flow condition on pollutant emissions using driving simulators

In the last 20 years the attention of international organizations towards air pollution has been improved, leading to definition of laws and regulations. In order to evaluate strategies and policies, forecasting tools have been adopted by institutions. Currently, the estimation of traffic emissions is based on static models, in which the amount of pollutant is computed as a function of average parameters obtained on a single road stretch. The well-known traffic increase of recent years has significantly changed the actual flow conditions, producing a strong rise of interferences. As this facet affects the operating condition of each vehicle, the use of a standard emission model at high traffic interference can lead to some inaccuracies. In such cases, instantaneous emission models introduce deeper capabilities; essentially, the pollutant prediction is directly tied to the engine vehicle operation point in reallike traffic condition. This second modelling approach has been adopted in the current work. A complete lumped parameter vehicle model has been built to be used as a virtual on-road emission/fuel consumption test unit. Investigations have highlighted the dependence of emission level and fuel consumption on drivers’ behaviour; indeed, the analysis took advantage of the experiments carried out in the virtual reality laboratory: on a typical highway geometry, characterized by a dual lane carriageway with three lanes each, three different flow conditions have been simulated. Once the relationship between highway interference level and drivers’ behaviour has been evidenced (in terms of emissions and fuel consumption), a relation between highway interference level and emissions/fuel consumption has been highlighted. Finally, in order to assess the differences

Driving Behavior in Weaving Maneuver: A Driving Simulator Study

In terms of road safety, as well demonstrated in previous studies, the combination of concentrated flows in one specific area might induce more critical maneuvers. In this contest, one of the crucial points for road safety are weaving lanes where different flow can perform different maneuver merging and diverging, producing some conflict points. Bearing in mind this facet, this particular elements, have to be designed with a specific geometry, in order to ensure both maneuver, deceleration for exit and acceleration for entrance in the main flow. The main goal of this paper is the analyze the exchange maneuver of vehicles by means of a real time driving simulator, which allows to evaluate the performance of car users when approaching the exchange of lanes under the same boundary conditions. More specifically, the present paper deals with the extension of previously performed research on this type of element. Therefore, same indicators, same analysis technique and virtual reality scenarios were adopted, in order to establish a comparison between two different conditions of approach to the weaving lane: the first with same speed between the main and the secondary flow, the second one, with a significant speed difference between the flows. The analysis of the maneuvers has been addressed at first under a geometrical point of view and then estimating the related risk parameters in line with the same indicators presented in the previous research (deceleration and risk area evaluated as longitudinal ant transversal distance between vehicles). The main results highlight that, under a geometrical point of view, in different speed condition between the two flows, car users tend to reduce the length of the maneuver, performing the weaving earlier and then occupying a reduced length of the lane in comparison at same speed condition. Under the point of view of risk analysis, results are more significant in terms of traffic flow management rather than in terms of lengths of the lanes. In case of flows with different speed, car users tend to use brakes more often, probably because they are calibrating the speed of the vehicle approaching the weaving lane.

State of Alertness During Simulated Driving Tasks

Grip strength testing is a common tool in healthcare evaluation due its predictive ability for a range of concerns including nutritional status, fall risk, and frailty. With respect to frailty, grip strength is one of the Fried criteria, which is the most widely used frailty assessment tool. One problem with maximal grip strength testing is that values might underestimate maximal force due to problems with motivation or discomfort associated with the maximal test. An innovative serious game using the Grip-ball dynamometer was designed to measure grip strength in comparison to the frailty threshold of Fried. Discomfort levels were assessed using a visual-analogue scale for the Serious Game, the Grip-ball in a standard test, and the Jamar dynamometer, which is the gold standard for grip-strength testing. Discomfort was significantly higher for the Jamar, which had a 95% confidence interval of 6.2-7.5, in comparison to 1.5-2.4 for the Grip-ball and 0.7-1.3 for the Serious Game. The Serious Game was able to identify individuals who were not able to produce sufficient grip force to pass the Fried threshold for frailty, while improving comfort levels for the users when compared to a Jamar dynamometer.