The episode of Tunnel Vision in which Mr Key trudges through the sewers declaiming sewer- and tunnel-related prose will be broadcast tonight at 9.00 PM on ResonanceFM. At least, I think so. If through cataclysmic mishap you miss it, it will be repeated on Saturday 15th at 4.00 PM.
UPDATE : And if, through a second cataclysmic mishap, you miss the repeat, I understand that a podcast will be available from Sunday 16th. Check the Resonance podcasts page.