"Essential services" means the erection, construction, alteration or maintenance, by public utilities or municipal or other governmental agencies, of underground or overhead gas, electrical, steam or water transmission or distribution systems, collection, communication, supply or disposal systems, including poles, wires, mains, drains, sewers, pipes, traffic signals, hydrants and other similar equipment and accessories in connection therewith; reasonably necessary for the furnishing of adequate service by such public utilities or municipal or other governmental agencies or for the public health, safety or general welfare, but not including buildings.