Some YouTube rabbit holes are worth the trip, like a foray into the genre of tunnel-cleaning trucks. It's next-level powerwashing porn.
These promo videos invariably have the best music tracks, too:
Check out the high drama as this tunnel gets a scrubbin':
It even makes washing solar panels awesome:
This one has the best before and after:
• Camion lavage tunnels (YouTube / Colas Suisse)