All signs seem to indicate that Petaluma is poised to silence SMART train horns except in emergency situations. In response to complaints about the horns while the Sonoma-Marin Area Rail Transit authority was testing trains and warning systems, Petaluma plans to implement quiet zones for city rail crossings on April 19th. City Engineer Curt Bates says he wrote a work order to purchase and install “No Train Horn” signs. Service along the 43-mile rail line from north Santa Rosa to downtown San Rafael is scheduled to begin in late spring.