It looks like this discussion has run its course.
Thanks to everyone who contributed. I look forward
to sharing more on other discussions.

One more thing before we finish: my experience with British motorways is that the concrete surfaced sections are significantly noisier, but I've been told that's not the case in Australia. What did you think of them?

Hi there BANJO ol' friend...

Your knowledge of the Hume Hwy is immense. I guess in my own defence we/I had somewhat tunnel vision looking out for errant motorists at the wheel of their cars, committing all sorts of terrible offence's. Similar to that of excessive speed by a couple of clicks; over the posted speed-limit.

FYI our Mr MILAT is currently cooling his heels in the 'super-max' section of Goulburn Gaol, and from all accounts is none too happy; finding the place all to restrictive to suit his needs. Moreover, he's reminded (often) the likelihood of his release, is at best remote if ever, which hasn't made him very happy either. And another unsubstantiated rumour, he's not made many friends among those with whom he shares facilities - perhaps we'll read someday he's the recipient of a 'sharpened ended toothbrush' hitherto dipped in excreta, that's been slipped adroitly between his ribs, into a lung? Or am I only hoping?

The man was not born of a mother's womb, he dropped out of the arse of a dog!

Dear Aidan,

Some sections of the concrete surfaces on the Hume Highway
were noisy but sections of asphalt were just as noisy.
What was annoying, the bumps between the various sections
and at bridge crossings.

PS:

Not to mention all the dismantled bodies of the
poor kangaroos that were at times unavoidable
as the car wheels hit the bones.

Dear O Sung Wu,

I'd forgotten about Ivan Milat being in the super max
section of the Goulburn jail. Hopefully that man will
never be released. My husband reminded me of Milat's
atrocities as we drove past the sign of Bowral. It gave me
chills just looking through the car windows.