Many different devices have been developed to measure skid resistance or road surface friction. They all assess skid resistance by measuring friction between rubber and the wet road surface in some way. However, there is no absolute value of skid resistance against which a measuring device can be compared. While it is possible to make test surfaces or identify in-service roads that have levels of skid resistance within a certain range, it is not possible to tell in advance what the actual skid resistance will be - especially as the measured value varies from one device to another anyway. The development of true reference surfaces would be a significant step forward on the road towards a harmonised approach to skid resistance measurement and reporting. The purpose of this report is to review the topic of test surfaces used for checking and calibrating skid resistance measuring equipment and the potential use of reference surfaces to contribute to the harmonisation purposes. The outcomes of this part of the study, in conjunction with deliverables D04 and D05 will then feed into the next stage of the TYROSAFE project to develop a road map for future harmonisation. For a survey of current practice, a detailed questionnaire was sent to project partners and, through them, manufacturers, operators of test equipment and those organisations responsible for equipment accreditation were approached. The purpose of this questionnaire was to see how different countries use test surfaces on roads or test tracks to calibrate their measurement devices, in the absence of "true" reference surfaces with known skidresistance characteristics. The general conclusion drawn from this part of the work was that many different surfaces are used as test surfaces, most often (but not exclusively) made from conventional road-building materials. However, because they do not have access to test tracks (there are not many of these in Europe), most organisations use in-service roads for their calibration checks. Consequently, the selection of test surfaces is not based just on a specific combination of friction and texture levels but on what is readily available on the road networks concerned.