old tarmac for gravel drive base?

[delboy]

Hi,
I have an ugly tarmac drive that cannot accomadate enough cars,
My idea is to dig out part the lawn area next to the drive, then dig up the tarmac from the existing drive and fill in the dug out area of the lawn using the tarmac as a base for a new gravel drive.
will this work?
how deep should I make the gravel?
will the dug up tarmac be ok as a base?
cheers!

[SandMan]

You will need to compact the tarmac, but first break it up as small as possible which makes it good for compaction, my past experience in using chippings is to have no less than 75mm else you be ever covering up the tarmac subbase all of the time.