There are two wires in the overhead and one rail in the street:
http://www.p.lodz.pl/I35/personal/jw37/urbtr/images/nancy-06-16.jpg
http://www.p.lodz.pl/I35/personal/jw37/urbtr/images/nancy-06-35.jpg
http://www.p.lodz.pl/I35/personal/jw37/urbtr/trsh-nancy.html
Phil