They have heard of route numbers but they do not know what they actually are.

Well there's one road that might not be true of - the N17, thanks to the Saw Doctors song about it:

Well I didn't see much future
When I left the Christian brothers school
So I waved it goodbye with a wistful smile
And I left the girls of Tuam
Sometimes when I'm reminiscing
I see the prefabs and my old friends
And I know that they'll be changed or gone
By the time I get home again.
And I wish I was on the n17
Stone walls and the grass is greener
Travelling with just my thoughts and dreams

Well the ould fella left me to Shannon
Was the last time I traveled that road
And ass we turned left at claregalway
I could feel a lump in my throat
As I pictured the thousands of times
That I traveled that well worn track
And I know that things will be different
If I ever decide to go back
Now as I tumble down highways
Or on filthy overcrowded trains
There's no one to talk to in transit
So I sit there and daydream in vain
Behind all those muddled up problems
Of living on a foreign soil
I can still see the twists and the turns on the road
From the square to the town of the tribes.