This is interesting. We can certainly look at the data for some of these streets, if you or others can give us more local knowledge to help evaluate the specific segments.
I have looked at many other devices in Oxford and none of these show this discrepancy, so it could be something to do with the set-up of the device on Howard Street which could be causing this.
In the past there were some issues with speed measurements arising from our night data, and we’ve recently started to purge some of the misleading data while we optimise the night count algorithms. I think we should already have done this for these devices, but we can take a look.