Complex sentence: When the voice automation system was installed in subway trains, the stop announcements on Line 1 trains referred to the station as "Sheppard" while the announcements on Line 4, however, refer to the the station as "Sheppard-Yonge".
Split into simpler sentences: When the voice automation system was installed in subway trains, the stop announcements on Line 1 trains referred to the station as "Sheppard". The announcements on Line 4, however, refer to the the station "Sheppard-Yonge".