That does seem a much more reasonable situation, than just allowing them to drive at 60 blind to any local requirements as implied by the earlier poster.
Out of interest, does (a) always apply, even when driving over lines that the driver does have route knowledge?
I've had a quick check. Basically, if a driver doesn't have the formally-acquired route knowledge themself, then there should be a conductor, but if there isn't, then they can drive alone as long as that specific route isn't barred for such activity. It comes in the successor to DS/DV 408, Ril 408:
"Bahnbetrieb Fahrdienstvorschrift / Züge fahren; Ohne Streckenkenntnis fahren, Ortskenntnis 408.2301 / Seite 1 / .... / 1 Ohne Streckenkenntnis des Triebfahrzeugführers fahren / (1) Wenn der Triebfahrzeugführer ausnahmsweise nicht streckenkundig ist, muss er fahren, wenn ihm ein streckenkundiger Mitarbeiter beigegeben wird. / (2) Darüber hinaus gilt: / a) Wenn ein streckenkundiger Mitarbeiter nicht zur Verfügung steht, darf der Triebfahrzeugführer auf Weisung seiner Auftrag gebenden Stelle fahren, ohne dass ein streckenkundiger Mitarbeiter beigegeben wird, soweit es im Streckenbuch nicht verboten ist. Er hat dann seine Fahrweise den Strecken- und Sichtverhältnissen anzupassen. / b) Die zulässige Geschwindigkeit beträgt auf Hauptbahnen 100 km/h, auf Nebenbahnen 40 km/h. Im Streckenbuch sind die Nebenbahnen und die zulässigen höheren Geschwindigkeiten bekanntgegeben."
(I don't know of an English translation. The key bit is (2), which says that if no colleague with route-knowledge is available, then if instructed his superior and if the line isn't barred for such an action, the driver can drive without a colleague with route-knowledge, adjusting his driving to line and visibility conditions, and not exceeding 100 km/h on main lines and 40 km/h on secondary lines.)
I'm pretty sure the requirement always to have the route documents in front of you was also in DV 408, but I can't find at a quick look in the completely re-organised Ril 408. However, the fact that all modern cabs have provision for the electronic display of the information (eBuLa) and you routinely see that it's in use suggests that the requirement is still there — and regarded as important, as the screens are immediately alongside the speedos in the ICEs.