This paper describes the method with which r+m, in conjunction with Publex, carried out research into the measurement of billboard coverage. First we will discuss the assumptions that are the basis of this study - central to this being - the premise that every billboard should be seen as a separate medium (comparable with a title in printed media). We will then go on to discuss the newly developed research model, by r+m and Publex, and the relationship between its central themes. After this - results produced until now from our research - will be used to show how far the model fits with earlier assumptions concerning billboard coverage. In conclusion we will look at future developments. This does not only mean research into further refinements of the model but also into the possibilities it presents for campaign evaluation.