Well spotted, Stu. DfT need you as a proof reader!
In relation to inconsistencies pointed out between Chapter 6 and TSRGD, DfT has said that TSRGD takes precedence and that TSM will be revised ‘at the next opportunity’. They will doubtless say the same for these issues.
The old TSRGD 2002 stipulated that the road hump warning sign (Diagram 557.1) could only be installed together with road markings (Diagrams 1004 and 1062) and supplementary plate. This is with regard to roads that are not within a 20mph “Zone” (signed using Diagram 674),
TSRGD 2016 has removed that link between warning sign and road markings. However, Chapter 4 of the Traffic Signs Manual doesn’t seem to quite recognise this. Figure 12-1 (the hump warning sign) says “May be used only in combination with the plates …. and with the marking to diagram 1062”.
In para 12.1.2, with reference to 20mph speed limits, “Hump markings are always required where a 20mph speed limit is signed using diagram 670”. And presumably any other speed limit?
Am I reading all of this right?
There may be circumstances where the hump markings alone i.e. no upright sign, would be deemed sufficient enough warning but Chapter 4 does not touch on this possibility outside of a 20mph “Zone”.