Dick de Waard

A SIMPLE PROCEDURE FOR THE ASSESSMENT OF ACCEPTANCE OF ADVANCED TRANSPORT TELEMATICS

There is no standard way of measuring driver acceptance of new technology. A review of the literature shows that there are almost as many methods of assessment of acceptance as there are acceptance studies. The tool for studying acceptance of new technological equipment that is presented here has a major advantage compared with many other studies in that esoteric knowledge of scaling techniques is not required. The technique is simple and consists of nine 5-point rating-scale items. These items load on two scales, a scale denoting the usefulness of the system, and a scale designating satisfaction. The technique has been applied in six different studies in different test environments and analyses performed over these studies show that it is a reliable instrument for the assessment of acceptance of new technology. The technique was sensitive to differences in opinion to specific aspects of in-vehicle systems, as well as to differences in opinion between driver groups. In a concluding section explicit recommendations for use of the scale are given.

The use of psychophysiology to assess driver status

Twenty subjects completed an on-the-road driving experiment, consisting of two different tests conducted on two separate days. A two-part test was administered while subjects were under the influence of alcohol (BAC < = 0.05%); a four-part test was administered without alcohol consisting of a 2.5 h driving test under vigilance conditions on a quiet highway. The order of the tests was balanced across subjects. Changes in relevant physiological parameters, such as ECG and EEG, reflected changes in driver status and predicted driving impairment. Impairment of driving performance was measured in a standard driving test (SD lateral position and SD steering wheel movements) and in a recently developed car-following test (reaction to speed changes of a leading car).

MEASURING DRIVING PERFORMANCE BY CAR-FOLLOWING IN TRAFFIC

The measurement of impairing effects on driving performance by such external factors as alcohol, medicinal drugs, or mobile telephoning, etc., is extended with a new test. Most existing methods of measuring impairing effects in the actual driving environment have the drawback that, irrespective of high sensitivity, they measure driving skills that are involved in only a very low percentage of accident causes, i.e., accidents after motor-response or eye-hand co-ordination errors. Since in accident causation, attention and perception errors predominate over response errors, on-road studies should examine specifically deterioration in attention and perception. The ability to follow a car in front, as measured by coherence and reaction time to speed variations, offers such a measure of attention and perception performance.

ASSESSING DRIVER STATUS - A DEMONSTRATION EXPERIMENT ON THE ROAD

Twenty subjects completed an on-the-road experiment that consisted of two parts on two separate days. One was a one-hour driving test under the influence of alcohol (BAC less than = 0.05%), the second a two-and-a-half-hour driving test under vigilance conditions. Impairment of driving performance was measured in a car-following test as well as in a standard driving test. Changes in relevant physiological parameters, such as ECG and EEG, reflected changes in driver status and predicted driving performance impairment.

CRITERIA FOR DRIVER IMPAIRMENT

Most traffic accidents can be attributed to driver impairment, e.g. inattention, fatigue, intoxication, etc. It is now technically feasible to monitor and diagnose driver behaviour with respect to impairment with the aid of a limited number of in-vehicle sensors. However, a valid framework for the evaluation of driver impairment is still lacking. To provide an acceptable definition of driver impairment, a method to assess absolute and relative criteria was proposed to fulfil the paradoxical goal of defining impaired driving which is consistent yet adaptable to interindividual differences.

Limiting speed, towards an intelligent speed adapter (ISA)

This study concerns the effects of a prototype intelligent speed adapter (ISA) on speeding in actual traffic. Twenty-four subjects were included in a test of effects of feedback on speed behaviour, mental workload and acceptance. Subjects drove an instrumented vehicle in normal traffic on various types of roads with different speed restrictions. Subjects completed the test route twice, half of the subjects received specific feedback in the second trial (experimental group), half of the subjects did not (control group). The groups differed in several ways, the most important being adaptation of their behaviour after feedback. Subjects in the experimental group behaved more according to traffic rules, in particular speed limits, than subjects in the control group. No significant differences in workload were found. Two types of feedback were tested to acceptance and were rated differently.

Plasma, oral fluid and sweat wipe ecstasy concentrations in controlled and real life conditions

In a double-blind placebo controlled study on psychomotor skills important for car driving (Study 1), a 75 mg dose of +/- 3,4-methylenedioxymethamphetamine (MDMA) was administered orally to 12 healthy volunteers who were known to be recreational MDMA-users. Toxicokinetic data were gathered by analysis of blood, urine, oral fluid and sweat wipes collected during the first 5h after administration. Resultant plasma concentrations varied from 21 to 295 ng/ml, with an average peak concentration of 178 ng/ml observed between 2 and 4h after administration. MDA concentrations never exceeded 20 ng/ml. Corresponding MDMA concentrations in oral fluid, as measured with a specific LC-MS/MS method (which required only 50 microl of oral fluid), generally exceeded those in plasma and peaked at an average concentration of 1215 ng/ml. A substantial intra- and inter-subject variability was observed with this matrix, and values ranged from 50 to 6982 ng/ml MDMA. Somewhat surprisingly, even 4-5h after ingestion, the MDMA levels in sweat only averaged 25 ng/wipe. In addition to this controlled study, data were collected from 19 MDMA-users who participated in a driving simulator study (Study 2), comparing sober non-drug conditions with MDMA-only and multiple drug use conditions. In this particular study, urine samples were used for general drug screening and oral fluid was collected as an alternative to blood sampling. Analysis of oral fluid samples by LC-MS/MS revealed an average MDMA/MDEA concentration of 1121 ng/ml in the MDMA-only condition, with large inter-subject variability. This was also the case in the multiple drug condition, where generally, significantly higher concentrations of MDMA, MDEA and/or amphetamine were detected in the oral fluid samples. Urine screening revealed the presence of combinations such as MDMA, MDEA, amph, cannabis, cocaine, LSD and psilocine in the multiple-drug condition.

Effect of road layout and road environment on driving performance, drivers' physiology and road appreciation

Infrastructural changes were implemented on rural 80 km/h roads in The Netherlands in an effort to reduce speeding. The road infrastructure changes were designed to produce discomfort for the speeding driver by providing noxious auditory and haptic feedback. On experimental roads, smooth-surface road width was reduced by using blocks of gravel chippings placed along the centre line and at intervals on road edges. It was predicted that these changes would increase mental load while driving, and thereby decrease speeding. In a field experiment 28 subjects drove an instrumented vehicle over experimental and control roads. A decrease in driving speed and swerving behaviour was found on the experimental roads, and this was coupled with a decrease in heart rate variability, consistent with an increase in mental load. Roads in two different road-side environments (woodland vs. moorland) were also tested. There were differences in driver appraisal of the two environments, but no interactions were observed between these appraisals and driving performance on the experimental roads. It is concluded that the infrastructural measures have a useful role to play in road safety through a reduction in driver speeding.

An experimental study to evaluate the effectiveness of different methods and intensities of law enforcement on driving speed on motorways

Two field experiments were conducted to establish the most effective method of enforcement in reducing driving speed and to establish the most efficient strategy in terms of police force personnel required. In the first experiment, the effect of three variables on driving speed on motorways was studied. The first variable, intensity of enforcement, was manipulated by creating three different objective levels of apprehension for detected speeding drivers. The second variable was method of enforcement. On-view stopping and ticketing of offenders was compared to mailing of fines on the basis of the cars licence plate number. The third variable manipulated was the time delay in the mailing of fines. Time delay between detection of the offence and feedback to the driver was shortened in one condition. In a second experiment, police enforcement effort was optimized by relating intensity level of enforcement to the proportion of speeding vehicles. In the first experiment, police enforcement was applied for four weeks; in the second experiment, enforcement activities were continued for 12 consecutive weeks. In both cases the main dependent variable was driving speed. Before, during, and after the application of enforcement, speed was registered using induction loops. In addition, driver opinion about speeding and speed enforcement was studied using postal questionnaire surveys. The results show the largest and longest lasting reduction in driving speed in the highest intensity level-condition, giving support for a relation between objective chance of apprehension and speed choice. On-view stopping of offenders was shown to be a more effective method to reduce driving speed than mailing of fines. Some of these results are discussed in the light of game theory. The questionnaire surveys indicated that most drivers did not notice the recurrence in enforcement activities due to infrequent passing of the sections of motorways studied. The preventive effect of police enforcement appeared to be far more substantial than its repressive effect. Enforcement primarily deters the current nonoffender from speeding.

Effects of MDMA (ecstasy), and multiple drugs use on (simulated) driving performance and traffic safety

RationaleThe effects of MDMA on driving behaviour are not clear, since the direct effects of MDMA on cognitive performance are reported as not generally negative.ObjectivesTo assess in an advanced driving simulator acute effects on simulated driving behaviour and heart rate of MDMA, and effects of polydrug use.MethodsA group of young participants who had indicated that they regularly used MDMA were asked to complete test rides in an advanced driving simulator, shortly after the use of MDMA, just before going to a party. They were tested again after having visited the “rave”, while they were under the influence of MDMA and a number of different other active drugs. Participants were also tested sober, at a comparable time at night. Separately, a control group of participants was included in the experiment.ResultsDriving performance in the sense of lateral and longitudinal vehicle control was not greatly affected after MDMA, but deteriorated after multiple drug use. The most striking result was the apparent decreased sense for risk taking, both after MDMA and after multiple drug use. This was clear from gap acceptance data, while the ultimate indicator of unsafe driving, accident involvement or even causation, was increased by 100% and 150%, respectively.ConclusionsDriving under the influence of MDMA alone is certainly not safe; however, driving back (home) after a dance party (“rave”) where MDMA users regularly combine MDMA with a host of other drugs can be described as extremely dangerous.