This deliverable presents an overview of some of the results obtained in the safety evaluation of incident warning systems as presented in a seminar organised by the HOPES project in May 1995, at the Drive Central Office in Brussels. Whereas the evaluation studies were planned as a coherent set of studies using multiple levels of indicators and a range of incident warning system implementations, the achievements of the studies were very much dependent on the successful and timely implementation of the incident warning systems planned in the pilot projects involved. Due to various factors, not all planned systems were actually realised. As a consequence, the seminar does not so much present evidence of the potential safety effects of the various systems under evaluation, as overview of the research methodologies, the quasi-experimental and experimental design and the dependent variables or indicators that can be meaningfully used to assess the safety impact of incident warning systems. The seminar shows that there is a wide range of tools at the disposal of those genuinely interested in the safety effects of incident warning signs. It also shows that the selection of the appropriate indicators is essential to the validity of the assessment, and that some of these indicators are sensitive to quite subtle variations in the design of the incident warning systems in terms of specificity and complexity.
Samenvatting