(Provisional) Development and Implementation of a Novel Intelligent Speed Adaptation System Based on Sight Distance

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Validation of a Driving Simulator for Road Tunnel Behavioural Studies

Introduction. According to European regulations, road tunnel safety is strategic in the management of national and international road corridors. Although the accident rate is lower in tunnels than on open roads, the severity of crashes in tunnels is higher due to the presence of hard lateral obstacles and limited space in case of lane departure. Driving simulation studies can support design decisions to assess the impact of any safety improvement albeit driving simulators must be validated to understand how the experimental results relate to real driving conditions. Method. This study deals with the behavioural validation of the fixed base driving simulator of the RSDS Lab for safety studies for tunnels. Field speed and lateral position data for vehicles were collected by image analysis of video sequences collected from the CCTV cameras in five sections of the Fréjus tunnel (Italy-France). The tunnel was faithfully modelled in the virtual scenario, and the same data were collected by extracting records at the same cameras’ stations. Thirty-five participants were involved in a between-subject experiment. Fifteen drivers with Italian B licenses drove a car, and twenty professional drivers with Italian C and/or D licenses drove a heavy truck. Results and Conclusions. Normality tests for data distributions and t-tests for the comparison between real and simulated data were conducted. The simulator achieved the relative validation for truck speeds (with values observed in the simulation always lower than those observed in real driving), and absolute validation with regard to truck lateral position. Opposite outcomes were obtained for cars, with absolute validity for speed and relative validity for lateral position. The relative-absolute validation of the driving simulator enables us to establish how experimental outcomes can be generalized to understand the impact of any safety countermeasure

Alternative Horizontal Markings along Curved Exit Ramp Terminals to Improve Driver-Safety-Related Performance

Previous investigation has revealed that diverging maneuvers along curved terminals lead to a deterioration in the longitudinal and transversal performances of drivers with respect to linear ones. As a countermeasure, innovative horizontal markings (HMs) may be used to compel drivers to drive more prudently and maintain better vehicle control. In this driving simulation study, the behavioral effects of alternative HMs along curved exit ramp terminals were investigated. Forty-eight voluntary par-ticipants drove along randomly assigned exit ramp terminals, the design of which involved combinations of the following input variables: (i) horizontal markings (standard HM1, with internal lane bands HM2, with external zebra stripes HM3); (ii) lighting conditions (day and night); (iii) traffic flow in the motorway (1,000 passenger cars per hour pc/h and 3,000 pc/h), and (iv) ramp terminal connection type (continuous and reverse). Longitudinal (i.e., speed) and transversal (i.e., lateral position and diverging abscissa) behavioral data were collected. HM2 leads to greater improvements in the level of road safety thanks to better longitudinal and transversal driver behavior. However, drivers did delay their exit from the motorway with respect to the baseline condition (HM1) independent of the connection type. No relevant improvements were observed with HM3, apart from speed reductions at the end of the terminal and more centered trajectories when approaching the ramp. Results also show that drivers tended to enter the reverse terminal later than the continuous one (where drivers correctly used the taper), thus revealing that the use of the innovative HMs was not able to compensate for this inappropriate behavior adopted along reverse terminals

What's around the curve? A driving simulation experiment on compensatory strategies for safe driving along horizontal curves with sight limitations

This paper focuses on the behaviours adopted by road users when negotiating horizontal curves with sight limitations. Experiments at a driving simulator were conducted on two-lane highways in which drivers were confronted with a range of sight conditions generated by the manipulation of variables such as curve direction, radii and distance of lateral sight obstructions along horizontal curves. It was observed that most of the drivers adopted strategies which resulted in a stopping distance shorter than the available sight distance, thereby maintaining safe driving conditions. Some drivers reduced their speed, some increased the lateral distance from any sight obstructions along the roadside, some did both, while others did neither. A preliminary analysis indicated that the safety benefits resulting from a vehicle speed reduction strategy significantly outweigh those from a lateral shift in the lane. Further analyses on the 1246 cases investigated offered further support for this proposition, while revealing that a higher proportion of drivers opted for the first strategy for safety reasons. Moreover, visibility conditions (safe, partially safe, and unsafe) played a role in the choice of driving strategies. Results provide evidence that a significant group of drivers used the two strategies under severely restricted visibility conditions (i.e., along sharp radius curves); however, the strategies selected were independent of the driver speed profile (i.e., slower, average, or faster)

How to take speed decisions consistent with the available sight distance using an intelligent speed adaptation system

Travelling at excessive speed increases the risk of having a road crash. Intelligent Speed Adaptation (ISA) systems might help the driver to make safe speed decisions along road sections with limited visibility. A recently developed ISA system, called V–ISA (Hazoor et al., 2021), is able to estimate the dynamic (real-time) speed limit, based on the prevailing sight conditions and stopping distance. The V-ISA operates in the following three ways: it can (i) display visual information, (ii) alert the driver with a warning sound, and/or (iii) intervene directly to modify and control vehicle speed. The effects of V-ISA on driving performance have yet to be investigated. Thus, the question of whether V-ISA modulates driving speed choice remains open. Here, we assessed the impact of V-ISA variants on driver speed choice. Thirty expert drivers experienced four simulated driving conditions, in which the three V–ISA variants together with the V-ISA off control condition were tested separately. Furthermore, drivers were asked for feedback on the acceptance and usability of the three V-ISA. Our results suggested that V–ISA was effective in mitigating the risks associated with speeding, with relatively high acceptance and perceived usability levels. The results indicate that V–ISA can have a positive impact on road safety by helping drivers to modulate their chosen driving speed

Intelligent speed adaptation for visibility technology affects drivers’ speed selection along curves with sight limitations

Sight obstructions along road curves can lead to a crash if the driver is not able to stop the vehicle in time. This is a particular issue along curves with limited available sight, where speed management is necessary to avoid unsafe situations (e.g., driving off the road or invading the other traffic lane). To solve this issue, we proposed a novel intelligent speed adaptation (ISA) system for visibility, called V-ISA (intelligent speed adaptation for visibility). It estimates the real-time safe speed limits based on the prevailing sight conditions. V-ISA comes with three variants with specific feedback modalities (1) visual and (2) auditory information, and (3) direct intervention to assume control over the vehicle speed.Here, we investigated the efficiency of each of the three V-ISA variants on driving speed choice and lateral behavioural response along road curves with limited and unsafe available sight distances, using a driving simulator. We also considered curve road geometry (curve direction: rightward vs. leftward). Sixty active drivers were recruited for the study. While half of them (experimental group) tested the three V-ISA variants (and a V-ISA off condition), the other half always drove with the V-ISA off (validation group). We used a linear mixed-effect model to evaluate the influence of V-ISA on driver behaviour.All V-ISA variants were efficient at reducing speeds at entrance points, with no discernible negative impact on driver lateral behaviour. On rightward curves, the V-ISA intervening variant appeared to be the most effective at adapting to sight limitations. Results of the current study implies that V-ISA might assist drivers to adjust their operating speed as per prevailing sight conditions and, consequently, establishes safer driving conditions

A Driving Simulation Study on The Effectiveness of Technologies Against Distracted Driving

Being distracted while driving is one of the main causes of road accidents. To counter the negative effects produced by distraction, onboard sensors, i.e., Technology Against Distracted Driving (TAD) may be used to (i) monitor eye activity, (ii) alert distracted drivers, and (iii) prevent the development of hazardous driving conditions. In this study, the effectiveness of a commercially-available low-cost TAD on participants, who were asked to perform a secondary task that involved a physical, visual, and cognitive distraction while driving, was assessed. Forty-two participants were randomly stratified (by age, gender, and experience) into three groups: (i) group A drivers drove without being distracted, (ii) group B drivers were distracted, and (iii) group C drivers were distracted but benefited from the presence of a TAD device. Driver performance was evaluated along a motorway segment using longitudinal and transversal behavioral factors. Drivers reduced speed and speed deviation when engaged in a secondary task, but experienced a significant deterioration in vehicle lateral control with respect to those in the control group. Conversely, when they used an anti-distraction device to contrast secondary task occurrence, their lateral control improved considerably but their longitudinal behavior changed. In particular, females maintained a prudent speed level to compensate for the distraction caused by engagement in the secondary activity, while males compensated by significantly increasing their speeds and speed deviations

Assessment of poisonous and anti-nutritional compounds in wild edible forages consumed by ruminant species

The present study was conducted to evaluate the anti-nutritional composition of the wild plantsof Soon Valley, Khushab, Pakistan. Anti-nutritional components posed a high risk to health for theruminants. So it is very important to estimate the range of anti-nutritional compounds present inthe wild plants which are used as forage by the ruminants of this area. Anti-nutritional compounds,such as terpenes, tannins, saponins, phytate, alkaloid, cyanide and oxalate were analyzed. Highestterpene contents (200.33%) were showed by Digitaria sanguinalis, Erigeron divergens showedmaximum alkaloid contents (0.93%) while highest cyanide value was observed in Achnatherumhymenoides (0.57%). Excluding cyanide, all anti-nutritional components showed significantvariation in all plant species. The values of anti-nutrients observed in the present study are belowthan the toxic levels. Bulk consumption of monotypic edible parts of plant during one meal maylead to nutritional and health problems. However, traditional methods help to lower down theanti-nutritionals and their respective risks. Similarly, wild edible plants can also be used toimprove the living security and thus reduce the starvation due to the millennium developmentgoal