I used it to say I have and because its free - I won't be using it after
But I must say, i was very impressed - the ventilation through the tunnel is excellent and your radio works the whole way, despite going under water! I think they've done well...
If I understand it correctly, the tunnel operators actually re-transmit certain stations. eg. In the Melbourne tunnel, a couple of the Geelong stations we listen to will cut out in the tunnel, but have perfect reception above ground.
This is also how they can transmit safety messages across the spectrum without interference.