D7.1 Methodology for the evaluation of interventions Safe tolerance zone calculation and interventions for driver-vehicle-environment interactions under challenging conditions

Abstract

This deliverable aims to provide the methodology for the evaluation of both real-time and posttrip safety interventions, which will be developed to improve driver safety through keeping the driver within the boundaries of the ‘Safety Tolerance Zone’. In particular, the methodology will cover all the features and particularities of each one of the interventions examined, as well as the statistical issues involved in effectiveness assessment of interventions. In order to evaluate the effectiveness of the safety interventions, the logic model of change behind the i-DREAMS interventions (comprising of Safety Outcomes (SO), Safety Promoting Goals (SPG), Performance Objectives (PO) and Change Objectives (CO) is presented and the dependency among the different levels was highlighted. Moreover, it was sought to link the SO, SPG, PO, and CO with driving behavior and safety critical indicators, in order to identify the potential measurements to be provided from the i-DREAMS platform and will be utilized for intervention assessment. For the interventions taking place in a professional work setting, data analysis and interpretation of results will have to take companies’ safety climate into account, as this can be expected to be a crucial environmental factor influencing intervention effectiveness. In line with corporate safety climate, individual user acceptance is also to be included in the analysis and interpretation of intervention effectiveness. In addition, an overview of past methodologies and frameworks from literature that have been used to assess interventions was described. It was revealed that safety promoting goals and performance objectives had the greatest effect on the assessment of interventions. Although safety constitutes the cornerstone of the i-DREAMS project, little evidence for safety outcomes was identified, due to the limited time framework of interventions and the fact that the crashes were rare events. Safety promoting goals (i.e. driver fitness, vehicle control, speed management) appeared to have an influence in a great extend for the assessment of interventions. Moreover, performance objectives, and especially, speeding, harsh acceleration, harsh braking, lane deviation and left turns had the strongest impact on the evaluation of interventions, while driver related characteristics such as distraction, stress, fatigue, drowsiness, attentions, concentration and blind spot appeared to have lower impact. The final section of the deliverable deals with the evaluation methodology, based on the aforementioned different safety levels of the logic model of change. The ultimate purpose of the methodology is a summative assessment focusing on outcome and process evaluation. At the beginning of the evaluation, appropriate research questions need to be defined and indicators, measures and determinants need to be outlined. The criteria, KPIs and user acceptance, acceptability and reliability factors, which will support the assessment are also thoroughly described in this document. Methodologically, three different methods are proposed: before-after analysis, case-control trials and questionnaires. With regards to before-after analysis, both quantitative (i.e. safety outcomes, safety promoting goals, performance objectives) and observed qualitative (i.e. change objectives) indicators can be utilized, and comparisons can be drawn using beforeafter or case-control study designs. Questionnaires, will be exploited mostly for the evaluation of qualitative indicators (i.e. change objectives) Finally, following the design of the assessment methodology, the crucial next step within the iDREAMS project is connected with the organization of the back-office database, which will provide all necessary data for the realization of the individual evaluations as well as the comparisons between different countries and transportation modes.