Some exciting news just in! We have established that the Transperth Bus Service that stops in front of Sonoma is Bus Route 353. (Stop No: 27605)
This route runs from Ellenbrook to Bassendean Train Station & return.
Good news is that according to the timetable Sonoma is only 15 mins bus trip to Bassendean Station, and then a 10 minute train ride to the CBD.