Longitudinal and Transversal Driver Behaviour with Innovative Horizontal Markings Along Curved Motorway On Ramps and Terminals

The manuscript presents a driving simulation study on the effectiveness of two innovative horizontal marking designs (in comparison with the conventional marking) along acceleration ramps and reverse and continue terminals on curved motorway sections. Longitudinal and transversal behavioural data were collected from forty-eight test drivers in response to variations in marking type, lighting conditions, and traffic-flow along the motorway. Although the innovative markings did not have a significant impact on speeds along continue terminals, they did have an impact on the lane gap and the standard deviation of lateral positions. Along the reverse terminal design type, their impact was evident on all the investigated longitudinal and transversal outcomes. This study proved that the perceptual techniques used by drivers engaged in speed and trajectory management along curved terminals are effective in promoting better driving performances

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

The influence of LED road stud color on driver behavior and perception along horizontal curves at nighttime

Scotopic lighting conditions (reduced level of natural light or presence of artificial lighting) may impair driving performance and, therefore, impact on road safety. Thanks to technological developments, low-cost light emitting diode (LED) studs are now being considered as an alternative and affordable pavement marking solution to assist drivers in these conditions. By helping them to maintain their vehicle within the marked lane, the studs should prevent any deterioration in driver performance when negotiating curves at nighttime. However, the few studies that investigated the impact of LED studs on driving performance produced inconsistent results, and the question of whether they actively improve driver performance remains open. Furthermore, while international road regulations allow the use of LED studs, they do not provide consistent prescriptions for their lighting color.Here, we assessed the influence of different LED lighting colors (red, white, and unlit) on longitudinal and transversal driver behavior when negotiating road curves with different radii and sense of direction. In the study, thirty-six drivers drove a dynamic virtual scenario featuring twenty-four curves. After the driving simulation, participants completed a static perception test in which they assessed each curve in terms of the perceived levels of risk, pleasantness, and arousal they experienced while driving on it.In comparison with the unlit and red lit curves, those marked with white lighting LED studs were perceived as less risky, less arousing, and more pleasant independently of the radii and curve direction. Furthermore, when entering these curves, participants tended to shift their driving trajectories towards the center of the road. This effect was most evident on the central part of the curve. Further studies are expected to corroborate these results by focusing on different road geometries and LED stud layouts, as well as testing driving behavior in controlled road field studies

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

Fate of Cajal–Retzius Neurons in the Postnatal Mouse Neocortex

Cajal–Retzius (CR) neurons play a critical role in cortical neuronal migration, but their exact fate after the completion of neocortical lamination remains a mystery. Histological evidence has been unable to unequivocally determine whether these cells die or undergo a phenotypic transformation to become resident interneurons of Layer 1 in the adult neocortex. To determine their ultimate fate, we performed chronic in vivo two-photon imaging of identified CR neurons during postnatal development in mice that express the green fluorescent protein (GFP) under the control of the early B-cell factor 2 (Ebf2) promoter. We find that, after birth, virtually all CR neurons in mouse neocortex express Ebf2. Although postnatal CR neurons undergo dramatic morphological transformations, they do not migrate to deeper layers. Instead, their gradual disappearance from the cortex is due to apoptotic death during the second postnatal week. A small fraction of CR neurons present at birth survive into adulthood. We conclude that, in addition to orchestrating cortical layering, a subset of CR neurons must play other roles beyond the third postnatal week

Glutamate Induces the Elongation of Early Dendritic Protrusions via mGluRs in Wild Type Mice, but Not in Fragile X Mice

Fragile X syndrome (FXS), the most common inherited from of autism and mental impairment, is caused by transcriptional silencing of the Fmr1 gene, resulting in the loss of the RNA-binding protein FMRP. Dendritic spines of cortical pyramidal neurons in affected individuals are abnormally immature and in Fmr1 knockout (KO) mice they are also abnormally unstable. This could result in defects in synaptogenesis, because spine dynamics are critical for synapse formation. We have previously shown that the earliest dendritic protrusions, which are highly dynamic and might serve an exploratory role to reach out for axons, elongate in response to glutamate. Here, we tested the hypothesis that this process is mediated by metabotropic glutamate receptors (mGluRs) and that it is defective in Fmr1 KO mice. Using time-lapse imaging with two-photon microscopy in acute brain slices from early postnatal mice, we find that early dendritic protrusions in layer 2/3 neurons become longer in response to application of glutamate or DHPG, a Group 1 mGluR agonist. Blockade of mGluR5 signaling, which reverses some adult phenotypes of KO mice, prevented the glutamate-mediated elongation of early protrusions. In contrast, dendritic protrusions from KO mice failed to respond to glutamate. Thus, absence of FMRP may impair the ability of cortical pyramidal neurons to respond to glutamate released from nearby pre-synaptic terminals, which may be a critical step to initiate synaptogenesis and stabilize spines

Dejar de vivir: al final en el laberinto: Postfolio

Una transposición de la noción de la inmensidad en las nociones del laberinto y del caos, examinando en paralelo el laberinto como construcción y el laberinto mental