we have the opportunity to compare Telraam S2 measurements to data of commercial devices (dialog displays), saving the data of car speed and number in to directions, not far away from our S2. However, beside minima and maxima, it provides the mean of speeds only, not V85. The mean, in turn, is not available from the Telraam output (at least not in the public sector, without using the API). A workaround would be, if I would just sum up the weighted values of the bar chart (% x speed category; using the mean speed (35 kmh for the category 30-40kmh)). However, I assume there could be a bias if the distribution is not even within the class.
Is there a more elegant way to get the mean speed recorded?
Our system does not currently calculate the Mean or V50 for speed. It has been requested elsewhere, so I will raise this internally and see how we might address this.
As you say, it might be possible to calculate it yourself. If you were to download the data it is probably something that could be calculated from the raw data easily enough, which would be better than using the percentages on the graph.
You can download your individual device data form your dashboard if this is of interest