What are those white lights at the bottom of the lamp pile?

With the addition of reflectivity, signs no longer need to be directly illuminated at night time. The headlights of the car combined with the reflectivity with the sign gives us plenty of visibility for signs.

However, if you've ever cleaned out a traffic management depot you may have noticed those white lights crushed at the bottom of the pile. These are the old lights they used to illuminate signs at night time. They should still be use for certain signs.

According to TSRGD 2016 all signs that cause people to stop, give way and terminal signs (speed limit triggers) are required to be illuminated when under street lighting at night time. This includes signs such as 'when red light shows wait here' and 'when stop sign shows wait here'. Personally I've never seen these signs illuminated under these conditions and there could be legal ramifications if a motorist fails to stop and causes an accident.