Verzilvering van de wegomgeving bij het invoegen op de (auto)snelweg:Leesbare, begrijpelijke en zinvolle informatie op dynamische informatiepanelen ter ondersteuning van de snelheidskeuze tijdens de invoegmanoeuvre voor oudere weggebruikers

Two studies were completed to determine in which way information could be presented to drivers on how to merge smoothly and safely into motorway traffic. First a selection of matrix sign information carriers, further referred to as signs, were developed. A selection was evaluated by a focus group on content, information density, lay-out, understandability and usefulness. On the basis of these results eight signs were selected for further analyses. These eight signs were presented on a laptop on which a driving simulator ride was played. Participants evaluated the signs on legibility, understandability, and usefulness. Both a group of older people and a younger control group participated. Results of the older group were the main focus of the study. As criterion for real world implementation suitability, or at least for further evaluation, a new composite measure was developed in which understandability ratings were counted twice as opposed to legibility and usefulness ratings that were counted once. The 85 percentile score was used to ensure that the majority of users actually assessed the signs positively. Out of the eight selected signs one was rated as very good, and one as very bad

Comparing treatment effects of oral THC on simulated and on-the-road driving performance: testing the validity of driving simulator drug research

The driving simulator provides a safe and controlled environment for testing driving behaviour efficiently. The question is whether it is sensitive to detect drug-induced effects. The primary aim of the current study was to investigate the sensitivity of the driving simulator for detecting drug effects. As a case in point, we investigated the dose-related effects of oral a dagger(9)-tetrahydrocannabinol (THC), i.e. dronabinol, on simulator and on-the-road driving performance in equally demanding driving tasks. Twenty-four experienced driver participants were treated with dronabinol (MarinolA (R); 10 and 20 mg) and placebo. Dose-related effects of the drug on the ability to keep a vehicle in lane (weaving) and to follow the speed changes of a lead car (car following) were compared within subjects for on-the-road versus in-simulator driving. Additionally, the outcomes of equivalence testing to alcohol-induced effects were investigated. Treatment effects found on weaving when driving in the simulator were comparable to treatment effects found when driving on the road. The effect after 10 mg dronabinol was however less strong in the simulator than on the road and inter-individual variance seemed higher in the simulator. There was, however, a differential treatment effect of dronabinol on reactions to speed changes of a lead car (car following) when driving on the road versus when driving in the simulator. The driving simulator was proven to be sensitive for demonstrating dronabinol-induced effects particularly at higher doses. Treatment effects of dronabinol on weaving were comparable with driving on the road but inter-individual variability seemed higher in the simulator than on the road which may have potential effects on the clinical inferences made from simulator driving. Car following on the road and in the simulator were, however, not comparable

Effects of alcohol (BAC 0.5\u89) and ecstasy (MDMA 100 mg) on simulated driving performance and traffic safety

Rational An increasing number of fatal road-accidents have been reported in which ecstasy was found in the blood of drivers. Although, ecstasy is frequently found to have been used in combination with alcohol, studies on the acute effects of ecstasy co-administered with alcohol on driving performance are relatively rare. Objective The present study was designed to establish the extent of driver impairment as a consequence of ecstasy or combined ecstasy and alcohol use as compared to driving under the influence of 0.3\u89, 0.5\u89 and 0.8\u89 alcohol. Furthermore, subjective performance was also assessed. Results Alcohol and ecstasy mainly influenced automated driving performance such as lateral and speed control. However, small to no effects of the substances were found on more complex driving behaviour. Overall, variance within the different driving measures was high especially when participants were treated with 3.4-methylenedioxy-methamphetamine (MDMA) and alcohol. Furthermore, equivalence testing showed that combined use may lead to impaired driving for some, but not all, drivers. Participants rated their own performance to be slightly worse than normal in both studies. Since driving was actually seriously deteriorated, this was a falsely positive assessment of their condition. Conclusions The dissociation between subjective perceptions and objective performance decrements are important notions for traffic safety since this may affect a driver’s judgement of whether or not it is safe to drive. For example, an intoxicated individual might decide to drive because the feelings of alertness caused by MDMA cloud the impairing effects of other drugs such as alcohol, thereby creating a potentially serious risk for traffic safety.Infrastructures, Systems and ServicesTechnology, Policy and Managemen

Determination of blood/serum ratios of different forensically relevant analytes in authentic samples

For forensic toxicological investigations only whole blood, but no serum is often available. Pharmacokinetic data are helpful for interpreting the results, but most of these studies indicate serum or plasma concentrations. In order to obtain reliable conversion factors which also take intersubject variability into account, the blood/serum ratios (B/S) of oxycodone, morphine, fentanyl, hydromorphone, zopiclone, MDMA, dexamphetamine, alprazolam, risperidone and 9-hydroxyrisperidone were determined by LC-MS/MS using authentic samples. Blood and corresponding serum samples were obtained from driving studies performed with controlled or known dosages of the above drugs. The analytes were analysed in blood and serum and the following mean B/S ratios (relative standard deviations) were determined: oxycodone 1.48 (8.19 %); morphine 1.03 (3.59 %); fentanyl 0.87 (13.9 %); hydromorphone 1.04 (8.11 %); zopiclone 0.89 (16.1 %); MDMA 1.19 (8.04 %); dexamphetamine 0.89 (10.9 %); alprazolam 0.81 (5.84 %); risperidone 0.65 (7.52 %); 9-hydroxyrisperidone 0.73 (12.3 %). These mean values are largely in line with those reported in the literature. The B/S ratios did not appear to depend on partition coefficients, whereas there was strong evidence that B/S ratios decreased with increasing plasma protein binding