Glad you like the pics.
Originally the tramway system used 550V DC, which was later converted to 650V. Since voltage doesn't matter too much for systems like this rumors say they're slowly raising to 750V, but that's not confirmed. The Stadtbahn always used 750VDC which is common for subway and long-distance (sometimes interurban) tramway systems around here. The interurban tramway to Baden uses 950V on their lines out of town, shares the U6 750V for a short distance and the tram 650V downtown. That's a real cool system A tramway, about 30km long I guess, linking all the small villages to Vienna, going every 7.5 or 15 minutes. It's the last remnant of the old lines that went far into the countryside.
The voltage is a reason why even the new Stadtbahn cars from 1954 (pic #3) had incandescent bulbs instead of flourescent tubes. Tramways used AFAIK a 220V flourescent tube and two 220V light bulbs in series. The Stadtbahn had 6 95V bulbs wired in series to get up to the 750V. Only the 1980 cars had inverters and flourescent tubes.
