Distance ‘D’ and the ‘when red light shows’.

The ‘When red light shows – wait here’ & ‘When stop sign shows – wait here’ needs to be a minimum of 15m from the light head or stop go board which it accompanies. However, the distance from first sign to the start of the lead in taper on a 30mph road is 20-45m. This isn’t a problem when you can put the signs at 45m but what if you can only put the first sign at a distance of 20m to achieve the minimum visibility required (60m) on a 30mph road (for instance where you have a bend on the approach). This would mean the chapter totalling 4 signs would be placed beside each other in a space of 5m which would not only look strange but also be hard to read for motorists. On top of this if you need to add a ‘joining traffic not signal controlled’ in the approach this would further tighten the space between the signs.

I've tried to show this below using dimensions & adding a hill detail.