In Austria we have a whole metro line which smells like vomit in the hot summer months - it's also the metro line which connects the most important tourist sites. So tourist get a very special smell of Vienna.
The reason is organic glue used in the 70ies during construction to harden the ground. So the smell is "baked in" the structure of the whole metrotunnel.
Your paragraph on this similar issue conveys almost the same level of info as the whole article and is equally interesting.
I don't see myself as a TLDR extremist, but I feel there's a cultural shift that needs to happen, or I am just personally ruined and doomed to get irked at verbose articles the rest of my days.
The reason is organic glue used in the 70ies during construction to harden the ground. So the smell is "baked in" the structure of the whole metrotunnel.
http://homepage.univie.ac.at/horst.prillinger/ubahn/deutsch/... (German)