A9 average speed cameras?

[Grandfondo]

When they are switched on how will they work?
Is it the average from the first one you pass to the last one, or each of the segments you pass through?

[Stevenr]

28th this month,each if the segments as far as I am aware.

[Grandfondo]

Cheers,the train sounds like a good idea if you want to keep your licence!