Here is a photo of the "guts" of one of these devices. It is a Bluetooth
tag - https://www.bluecats.com/product/bc313-tag/
I have heard, but can't confirm, that they are used for something far more
mundane than vehicle tracking or announcement triggering - to allow the
contractors who clean the stops and replace timetables etc to log where
they have been.
On Thursday, October 15, 2020 at 11:06:54 AM UTC+11 Mal Rowe wrote:
> On 15/10/2020 10:47, David Batho wrote:
> Would it be some kind of ‘transponder’ for the tram’s location, or to trigger appropriate announcements in the tram as it approaches the stop?
> I think you are right David.
> I suspect the thick white discs are new 'signposts' for the AVM (Automatic
> Vehicle Monitoring) system.
> I did a search of Vic tenders and they pur out a tender for an upgrade to
> the old AVM system, last year. It included the following line:
> *"The AVM uses radio signposts (270 on the network) and odometer to locate
> trams, which are reported as being the last-reported distance (meters) past
> last signpost, and is shown to Controllers textually, as well as on
> character-based line maps. Meanwhile there are 1700 stops on the network,
> of which the system is not aware."*
> So I am assuming these are the new stop based signposts, but I don't know
> why there are sometimes 1 and sometimes 2 - it could be a roll-out change
> in progress.
> My understanding is that the plan was to go to GPS, but it was found to be
> unreliable in the Melbourne CBD due to high rise buildings.
> Mal Rowe - observing change