Speed signs at Construction Zones

Question

If you are travelling on the N1 South near the Diepkloof interchange the speed limit drops to 60km by the construction site. The freeway then splits into N1 & N12. If you continue on the N1 South there are signs that signal 60km zone. If you take the N12 split there are no road works and no signs at all until +- 1km then its 120km. I want to know if once you take the N12 split is that automatically a 120km zone and if not why dont they put up a sign that says 60km? The JMPD are trapping under the bridge just after the split on the N12, but before you can see the 120km sign, is this allowed if there arent any speed reduction signs.

Answer

The previous road sign will apply if there is no other intersecting roads.
 
The speed limit that is posted applies, but if it clearly looks that the lower limit should not apply it may be worthwhile taking it up with Adv Dicker and Director Gernicke of JHB Metro.
 
I have had quite a few enquiries on this as I know of about 12 persons who were charged who were all under the impression that the speed limit  is 120 km/h there.