I wrote the following in the " General QR City thread " on 2nd Sept. I think it may answer your questions...…
Since the introduction of the NGR's there have been an increased number of noise complaints in the Brisbane area as their whistles are much louder than other classes. The situation was highlighted on Current Affair a few months ago.
On the Cleveland line 4 consecutive stations have level crossings - Lindum, Wynnum North, Wynnum, Wynnum Central. The named stations except Wynnum have the crossing at the immediate end of their platforms. The Wynnum crossing is about 100 metres away.
Before entering the platforms there are "W" signs. Stopping trains sound their whistles at these signs, stop at the platform then sound again on departure ( at the crossings ).
I have noticed in the past couple of weeks an "EXP" sign has added to the "W" signs approaching the platforms. My guess is that stopping trains no longer have to sound their whistles prior to stopping, and only the expresses/empties need to do so.
Through Wynnum there are about 20 expresses/empties in both directions per weekday.
The "W" sign before the Glenora St crossing on the UP line between Wynnum North and Wynnum does not have an "EXP" added, making me think my thoughts might be correct. Attached is a photo of these additions on the bi-di tracks before Wynnum North platform.....
Footnote....Since writing this article 4 days ago it appears my assumptions are correct. Expresses only using their whistles now at the designated 'W' signs, at least at Wynnum North which is my station.