On Sat, 17 Jun 2006 14:32:24 +0100, Dave Fawthrop wrote:

On Sat, 17 Jun 2006 14:02:46 +0100, Steve Firth
wrote:

|I would suggest that you start with a solar panel, and then add a wind
|gneerator if necessary. However I also work on eletrical/electronic
|installations on motorways and if you look you will see that for low
|current drain stuff we use solar only, for higher drain uses we have both
|wind and solar.

What are those green boxes which you see beside motorways, with a solar
panel on the top?

They are traffic counting devices. The box is linked to a set of loops
buried in the road surface one pair of loops in each lane. You can usually
see the loops as a shiny outline on the road surface. The green box counts
traffic flow and sends the data back to the National Traffic Control
Centre. NTCC use the data to work out where there are serious delays and
then set messages on the EMS signs to divert traffic around the problem.