The company behind that software, HAFAS (which is used almost everywhere in the German-speaking countries) constantly advertises for C++ and Java positions. As far as I'm aware the main part of the software, including the web facing portions, is written in C++.
The software has a long history, the first webserver with it was started in 1995 and even that most likely reused logic from their first version of 1989. So the language choice is not too surprising.
