[flavio81]

Thanks for this post!

>I'm sure Clojure would have been chosen if it was developed today.

Clojure was already available in 2013. The paper shows they made use of the CLOS object-oriented system, which is a key feature of Common Lisp.

[cutler]

2013 is just the publication date. The document cites an implementation of their London Underground system which has been in production since 2008 and a another within the Dutch rail system dating back to 1998.