There seems little point, considering traffic growth, in expanding carriageways by one or even two lanes. Five or so years later they will doubtless be overwhelmed.
Far better go the whole hog don’t you think and add a second M25 deck for use as a toll road à la Bangkok for example.
Those with bottomless pockets can speed along the upper levels whilst the remainder, stuck in the jam below, will have the luxury of time to deliberate the necessity of their journey.
We need less traffic not more road!
BEN ZABULIS (M), 31 Redhill Lodge Drive, Redhill, Nottingham