There is also a small amount of trolley service in Budapest. Their network consists of 13 routes covering 57 km of track, mainly in the inner city. All of the route numbers are higher than 70, because the first line began operating of Stalin's 70th birthday. The trollies are of limited convenience, subject to the same traffic delays as buses, but without their random route capabilities. However, because they are electric, they do not contribute to Budapest's enormous pollution problem. The Budapest Transport Authority (BKV) once attempted to phase out the service, but this attempted has failed due to pressure from environmental interests.