Felly sgrifennodd Tudor Hughes :
The traffic just
about keeps going under normal conditions but anything that slows the
flow will soon cause long delays.

Well, anything that increases the stopping distances can cause delays,
as motorists leave larger gaps between the cars. Merely slowing the flow
can have a positive effect, up to a point, as seen from the variable
speed limits around parts of the M25 and M42.

Adrian

--
Adrian Shaw ais@
Adran Cyfrifiadureg, Prifysgol Cymru, aber.
Aberystwyth, Ceredigion, Cymru ac.
http://users.aber.ac.uk/ais/weather/ uk