Complex sentence: While this function proved useful at above-ground stations and termini (especially in winter), station dwell time was significantly increased, and passengers had trouble getting used to the new system, not knowing how to open the door.
Split into simpler sentences: While this function proved useful at above-ground stations and termini (especially in the winter months), it did cause a few problems. Station dwell time was significantly increased, and passengers had trouble getting used to the new system, not knowing how to open the door.