For Objective 1, Dr Eriksson conducted semi-structured mental models’ interviews with 34 UK drivers and 20 Swedish drivers. Drivers answered open-ended questions about causes of accidents, when they speed and why, and when they do not speed and why. Interview responses were summarized, categorized, and key themes were included as questions in the confirmatory survey questionnaire (see Objective 2).
For Objective 2, Dr Eriksson developed an online survey based on the interview data (collected for Objective 1), to investigate the prevalence of misunderstandings of accidents risks and which reasons for speeding and avoid speeding were most common. Data analysis drivers’ identified risks and their importance in causing accidents and national accident statistics data. There was an English version of the survey, as well as a Swedish translation. 183 UK and 183 Swedish drivers answered the survey.
For Objective 3, Dr Eriksson designed two online surveys to investigate drivers’ travel time judgments and test an intervention. The intervention was a dashboard tool with information about speed and pace data. In the first survey, 142 UK drivers and 100 Swedish drivers participated. The data analysis compared performance on travel time tasks between the intervention and a control group. Performance was measured both as accuracy and time to decision. The time analysis was used to set time limits to induce time pressure in the second survey. 382 UK drivers and 201 Swedish drivers participated in the second survey. An intervention and control group were randomly assigned to a time pressure and time delay condition. Data analysis included comparisons of how well participants performed under time pressure and with a time delay.