This report describes the calculation of road surface friction based on texture values. The friction is measured with a ROAR device and stored every 5 m. The texture is measured with a laser and stored every 0.5 mm. Both types of devices are mounted on the same equipment having a laser and a ROAR positioned in the outer and inner wheel path. This makes it possible to measure friction and texture values in the same run in both wheel paths. Wavelet transformation of the texture profile has been used as an index to be correlated with the measured friction. Calculated MPD (Mean Profile Depth) values in accordance with the ISO standard 13473-2 have also been analysed. In Denmark, road pavements with a friction value below 0.40 measured by the ROAR, are regarded as slippery roads and hence the analysis has mainly dealt with data obtained on pavements with friction below 0.40. The analysis showed that the calibration of the distance measuring devices for the texture and the friction plays an important role for obtaining a good correlation between the friction and texture measurements. It was discovered that differences up to ± 5 m between the different distance measures could occur on a 3 km road section. The report shows some mathematical methods, which can compensate for the differences in the distance measurements and hence positions the measured data equally. The models described in the report, which calculate road surface friction based on texture data, gives a good correlation between the two data for sections having low friction levels, although the difference in the distance measures complicates a qualitative comparison between the calculated and the measured friction values. For road sections with a high friction level, the calculated friction values are higher than the measured friction values. This is however considered not being critical, as the target is to pinpoint the road sections with low friction. As a by-product of the data analysis it turned out that road surface friction values are mainly related to the wavelet coefficients associated to the wavelength length between 7 and 8 mm.