Here is the example sentence:
Nach einer betrieblichen Störung in Hegermühle kommt es leider zu Verspätungen und eventuellen Ausfällen.
It was an announcement taken from S-Bahn Berlin's website.
I was wondering if zu is used as a preposition here? And if so, what case (Dativ?) is this phrase zu Verspätungen und eventuellen Ausfällen in?
Yes, zu is a perfectly ordinary preposition here.
Zu is just one of many short function words serving grammatical purposes that can also serve as common content words; the article der is also a relative pronoun or a demonstrative pronoun, the verb affix an- also serves as a normal preposition, etc.
The example sentence might be slightly hard to read because the particle zu is used with infinitives, which tend to end in -en, while here the preposition zu governs dative plural forms, which also end with -en. As you see, inflection endings also tend to get reused. Nevertheless, context usually makes it clear enough what kind of zu you're dealing with.
