The joint tram network of the VBZ and VBG comprises 15 separate routes. The network operates on meter gauge track, electrified using overhead line at 600 V DC. The VBZ infrastructure is largely street based, with varying degrees of segregation from other street traffic but little use of dedicated rights of way for the trams with the notable exception of a tram tunnel in north-east Zürich that was originally built for an abortive metro system, and modified for tram usage. By contrast, on VBG infrastructure, VBZ trams operate on long stretches of dedicated track.