What does the term "O'Leary Blvd" most likely refer to?

The term "O'Leary Blvd" most likely refers to a station location because names that include "Boulevard" typically indicate a location where transit services are offered, such as train or bus stops. In transit systems, station names often reflect streets, avenues, or notable locations to help passengers identify where they can board or alight from transit services.

In contrast, the other options mention specific elements of transit infrastructure but do not match the naming convention typically used for stations. A rail yard generally pertains to an area where trains are stored or serviced, which would not commonly include a "Boulevard" in its title. Similarly, main line tracks represent the primary routes trains travel upon, while a signal control center refers to the operational hub that manages train signals and operations. Therefore, the naming of "O'Leary Blvd" aligns with how station locations are designated within transit systems.