The message
from "Dave Plowman (News)" contains these words:

Far more likely their long life if correctly driven. If energy consumption
was important with traffic lights they'd turn them off overnight, etc.

In the States they installed them for energy savings. There was an
article about it in New Scientist once, or at least, a side item.
Apparently at the time LEDs were more expensive than they are now so
they only changed the red and green. The ambers weren't on long enough
to make the payback worth it.

The outcome across the whole of the union was roughly equivalent to the
output of a medium sized power station IIRC.

--
Skipweasel
Pay no attention to that man behind the curtain.