At what speed can a bus driver continue driving in the lane marked by this sign?

Erklärung
The struck-through settlement board shows that the built-up-area regime does not govern this stretch, so the bus keeps its 90 km/h ceiling; the blue circular sign with the downward-arrow plate sets a 60 km/h minimum for that lane. The lawful band is therefore from 60 km/h through 90 km/h, and capping it at 70 km/h or treating 60 km/h as the only permitted speed misreads a minimum as a maximum.