Direction to be followed (D1)

"The signs indicate that the vehicle may only be driven in the direction of the arrow or, in the case of two arrows, in either arrow's direction. The symbol is adapted to the conditions of the location."

Direction to be followed (D1)

The arrow indicates straight on, you may only drive straight on and not turn left. There could be many reasons for this on this road. One example can be that there is heavy traffic. If a car were to stand still at the intersection a bottle neck could form behind you

Mandatory signs

"Unlike prohibitory signs, mandatory signs provide information to the road users regarding how they should behave, for example, to turn in a certain direction or that pedestrians are to use the path reserved for them. There is therefore a more positive implication with mandatory signs compared to prohibitory signs, and where an option is presented, it is thus generally better to use mandatory signs than prohibitory signs."

Driver license handbook