Suitability of averaging GPS/GNSS paths to build geometrically correct digital road maps

At present, almost all vehicles have one or more GPS receivers on board. Usually these receivers work in point positioning mode, with deviations of several meters in planimetry and even higher in altitude. Such accuracy is not sufficient for the representation of the road network, both for assisted and automatic navigation purposes and for the creation or updating of large-scale maps. Many free cartographic sources are based on the idea that the continuous repetition of tracking with point positioning receivers makes the measurements converge towards results closer to the actual position of the roads travelled. Here we have experimented whether, by averaging the results of hundreds of tracks found on the same route, we can arrive at accuracy compatible with those needed for navigation and cartography that we have set here compatible with that for the traditional cartography scale 1:5000. The results show that in good conditions of visibility of the sky good results are obtained by averaging a limited number of tracks, more paths are needed in urban areas, while results are not reliable in areas with dense vegetation cover.