The tram network operates 24 hours a day - from 4AM to 12AM there are 15 "day-time lines" (tram lines 1-9, 11-15 and 17), and from 12AM to 4AM there are 4 "night" lines (tram lines 31-34) which cover most of the day-time lines on a reduced (around 30-40 minute) frequency.