Proactive Evaluation of Traffic Signs Using a Traffic Sign Simulator

Traffic signs and pavement markings are a crucial aspect of road design since they are essential sources of information for road users to calibrate their driving behavior, evaluate route possibilities and cope with unexpected events. A proactive evaluation of (the quality of) these road design elements will help to improve the safety performance of the roadway. This paper presents the Traffic Sign Simulator, an innovative research tool to study the influence of these elements on road users’ routing decisions, lane choice and visual behavior, to investigate road users’ comprehension of these signs, and to collect suggestions for improvements. Using a driving simulator mock-up, participants navigate through a full HD video from route(s) in which the planned traffic signs have been digitally implemented using specialized software for camera-tracking and 3D video-integration. Participants’ route and lane choice and their visual behavior (using eye tracking) are monitored while driving through the scenario(s). Laptop preand post-tests are applied to collect additional in-depth information concerning the participants’ processing, comprehension and general evaluation of the traffic signs and suggestions for improvement. The paper illustrates the possibilities of the Traffic Sign Simulator with a case study that examined the effectiveness of temporary work zone signalization (i.e., traffic signs, digital information panels and pavement markings) as it was used during the reconstruction works on the Vilvoorde fly-over near Brussels, one of the busiest interchanges in the Belgian motorway network

The impact of perceptual countermeasures on driving behaviour in rural-urban transition : a driving simulator study

Many journeys include transitions from a road stretch where the speed limit drops from higher values to lower values. These transition road segments (i.e. rural to urban) are more complex for drivers because of changes in the road environment combined with sudden speed changes (i.e. 70 kph to 50 kph in Flanders) which often yield to an inadequate adaption to the speed limits. As speed influences both the probability of a crash and its severity, these transitions could be considered as higher accidents prone zones. Furthermore, logistic models describing the relationship between impact speed and pedestrian fatality risk show that the risk increases very rapidly for any small increase in the impact speed after 50 kph. Therefore, appropriate speed management at rural to urban transitions between 70 kph and 50 kph is essential. Different types of approaches have been used to manage driving speed on roads. Allpress & Leland argued that perceptual countermeasures shape the roadside environment designs to increase drivers’ estimation or feeling of speed. This increased perceptual speed might result in an actual speed decrease. Furthermore, as previously tested by researchers, perceptual countermeasures were one of the acceptable possible solutions to adequately reduce driving speed and increase road safety at transitions. In this study, we focus more specifically on optical pavement markings of which various types exist. Optical speed bars (OSB) with reduced spacing in travelling direction were used to increase drivers’ perceptual speed; while dragon teeth markings, peripheral transverse bars and herringbone pattern were used for producing road narrowing effect. To achieve combined perceptual effects of increasing drivers’ attention, increasing perceptual speed and creating road narrowing effect, researchers tested combinations of different treatments. In the current study, we aim to achieve combined perceptual effects (i.e. increase drivers’ attention, perceptual speed and perceptual road narrowing effect) by implementing a single treatment using a driving simulator. To achieve combined perceptual effects, we introduced Optical Circles ‘OC’ with increasing diameters based on the concept of forced perspective illusion and compared with a modified form of the commonly used speed bars (i.e. Optical Bars ‘OB’ with increasing widths and decreasing spacing). To the best of our knowledge, circle markings have never used for this purpose while speed bars are commonly used with fixed width and decreasing spacing

Humoral immunity to SARS-CoV-2 in kidney transplant recipients and dialysis patients: IgA and IgG patterns unraveled after SARS-CoV-2 infection and vaccination

Background: Infection with SARS-CoV-2 in high-risk groups such as kidney transplant and dialysis patients is shown to be associated with a more serious course of the disease. Four years after the start of the COVID-19 pandemic, crucial knowledge on the immune responses in these patient groups is still lacking. Therefore, this study aimed at investigating the humoral immune response after a SARS-CoV-2 infection compared to vaccination as well as the evolution of immunoglobulins over time. Methods: Kidney transplant recipients, patients on haemodialysis or on peritoneal dialysis and healthy controls were included in this longitudinal multicenter study. SARS-CoV-2 anti-RBD, anti-NP and anti-S1S2 immunoglobulin G (IgG) and A (IgA) as well as the neutralizing antibody capacity were measured. Results: Kidney transplant recipients had a significantly better humoral response to SARS-CoV-2 after infection (86.4%) than after a two-dose mRNA vaccination (55.8%) while seroconversion was comparable in patients on haemodialysis after infection (95.8%) versus vaccination (89.4%). In individuals without prior COVID-19, the IgG levels after vaccination were significantly lower in kidney transplant recipients when compared to all other groups. However, the IgA titres remained the highest in this patient group at each time point, both after infection and vaccination. A history COVID-19 was associated with higher antibody levels after double-dose vaccination in all patient categories and, while decreasing, titres remained high six months after double-dose vaccination. Conclusion: Kidney transplant recipients had a more robust humoral response to SARS-CoV-2 following infection compared to a two-dose mRNA vaccination, while patients on haemodialysis exhibited comparable seroconversion rates. Notably, individuals with prior COVID-19 exhibited higher IgG levels in response to vaccination. Hybrid immunity is thus the best possible defence against severe COVID-19 disease and seems also to hold up for these populations. Next, it is not clear whether the higher IgA levels in the kidney transplant recipients is beneficial for neutralizing SARS-CoV-2 or if it is a sign of disease severity.SCOPUS: ar.jinfo:eu-repo/semantics/publishe