English title : Distraction by non-driving activities : feasibility study. For some driver secondary tasks it has been shown in laboratory as well as field studies that they have detrimental influences on driving. But it is mostly unknown how often and in which situations these tasks are executed while driving. However, only from the integration of frequency and riskiness of a given secondary task it can be estimated how its execution influences accident risk. Four study types are feasible for the examination of frequency and riskiness of secondary tasks. The question of riskiness can be answered in an effective way in simulator experiments although here generalization on real driving is questionable. In naturalistic driving studies, frequencies of task executions as well as their riskiness can be gathered in real traffic. Results of these studies are most valid. However, naturalistic driving studies are high in financial demands as well as in time consumption. Information on secondary task frequency may be alternatively gathered by surveys. Herein, on the one hand, drivers could be interviewed in a face-to-face situation instantly after their driving trip. On the other hand, a representative sample of drivers could be asked to fill in a driving-diary by registration of their secondary tasks while driving. Both types of surveys enable an effective approach to a representative sample of drivers and secondary tasks frequencies. For both survey types it is essential that secondary tasks can be and are reported by drivers. All of these approaches need a definition of driver secondary tasks. In a literature analysis, a catalogue of relevant driver secondary tasks has been developed. In the analyzed literature, two types of studies have been prominently found. One the one hand, there were statistical accident data from different countries. On the other hand, driver observational studies have been conducted. In accident studies it was found that 10% to 30% of all reported accidents were due to driver secondary tasks. In observational studies driver have been found to execute secondary tasks while 30% of their driving time. Results show that not every secondary task done raises drivers´ accident risk, but for some special tasks in certain driving situations, a significantly higher accident risk is found. However, results are very heterogeneous and for Germany in particular, unfortunately almost no data exists. On this background a feasibility study was conducted, interviewing approximately 300 drivers. It was tested if face-to-face interviews instantly taken after a trip are feasible for gathering driver secondary task information for Germany. Five different driver groups were identified within the sample. These groups also showed different patterns of secondary task engagement. Eighty percent of drivers reported to have executed one to three secondary tasks within the last 30 minutes of driving. Looking at secondary task duration, result showed that interaction with passengers and operating non-driving related technical devices lasted longest. Subjective reports can be summarized by showing that drivers are aware that secondary tasks can be dangerous while driving but that they also believe that these tasks they have executed have not been distracting or dangerous. These believes show why drivers are this often and this long occupied with secondary tasks, as they seem to be confident that secondary tasks may become dangerous, but in their certain situation, this is not the case. From a methodological point of view, using face-to-face interviews directly after the trips can be evaluated as a success. Drivers are well able to report their tasks and thus it is possible to get an assessment of driver secondary task engagement quite fast and with much less time than it is required by naturalistic driving studies. The high responder rate and the similar results as compared to other studies support the impression that drivers honestly report their engagement in secondary tasks to their best knowledge. It has been shown that secondary tasks are a relevant problem field in Germany, concerning frequencies of tasks as well as durations. Results should be replicated using bigger samples that include other driving situations (exempli gratiaa nighttime, other seasons, other destinations) as well as other driver groups (truck drivers in cities). Using the presented approach, this would be possible with a limited effort. The original report contains the interview sheet used in the study as an annex. The reproduction was omitted in the present publication. It is available at the Federal Highway Research Institute and can be viewed there. (Author/publisher)
Samenvatting