Can you expect not to see warning signs behind the visible sign compelling drivers to drive slowly?

In the video, you are driving along a street in a housing estate in a town and approaching the entrance to a side street; on the right there is the blue sign D-40 "residential area", and just in front of you there is a pedestrian crossing. Beyond the visible sign, devices forcing slow driving might not be marked with warning signs. The answer is: yes.

The Regulation on road signs and signals states that sign D-40 marks the entrance to a residential area and also informs you that devices and solutions forcing slow driving placed in the residential area might not be marked with warning signs. This means speed bumps, raised junctions, chicanes and narrowings - outside the area there would be sign A-11a before a speed bump, but inside the area it may be missing. The rule is logical: in a residential area the Road Traffic Act limits speed to 20 km/h, a pedestrian may use the whole width of the road and has right of way over vehicles, and parking is allowed only in designated places - at such a speed a bump is not a danger, just a reminder. When you drive past D-40, you slow down to 20 km/h, drive ready to stop for a child running out from behind a car, and expect a bump round every bend, including an unmarked one.

Legal basis: § 58 para. 1 and 2 of the Regulation on road signs and signals; Art. 20 para. 2, Art. 11 para. 5 and Art. 49 para. 2 point 4 of the Road Traffic Act (Prawo o ruchu drogowym)