during this period, the services to zárate and campana were run with diesel locomotives by us company alco. by 1970 the municipality of buenos aires built a tunnel on avenida del libertador that passed under the retiro-tigre branch. between 1985 and 1985 ferrocarriles argentinos (that run all the urban services by then) signed agreements with different municipalities of greater buenos aires to build more tunnels to replace the level crossings existing in those districts.