Re: Fwd: Melbourne trams
  Matthew Geier

On 14/10/20 3:10 pm, Mal Rowe wrote:

> I know the E's have cameras that can record what's in front of the tram, but don't know if they are 'always on' or turned on by the driver.

> Yarra have published video of dangerous behaviour, so I assume there are some recordings.


> Can anyone help with more info?


I can't say what actually happens on the E class, but I've some experience with a camera system - the one fitted to the Sydney Variotram. It's a 15 year+ old box, and I know 1000s of these are in buses. It's a 'X11 MDVR' Appears to have been OEMed out of China by a local distributor. (Who once I found them, were most helpful about information for a device they haven't sold for over 10 years).

On the Variotram the 7 camera's record all the time - if the battery is on, the cameras are recording. The camera's have microphones, but looking at the MDVR boxes we ripped out of the other trams, some were configured to record cab audio and some were not.

The recorder buffer isn't a ring, when the disk fills the recording stops, so they have to be regularly serviced. This is done by removing the hard disk and connecting it to a PC where very clunky propreitory software can download the video files and delete the old recordings. The hard disk appears to be able to hold about a months worth of recordings. Of course different sized hard disks could be fitted. (Standard 3.5" SATA)

The recorder has many options, including a motion sensor, GPS and mobile data connection. It can also log various vehicle functions. The Variotram recorders only had motion and GPS. No 3G modem or other vehicle functions monitored.

The recordings are time and location stamped (GPS). There is an 'alarm' flag as well, where the sudden jerks detected by the XYZ movement sensor trigger an alarm.

The downloading software has the ability to search for these alarm flags.

The system on the E class would be using digital cameras, the MDVR X11 uses analogue cameras and the video is digitized in the box before being saved to the hard disk.

Note that even if only triggered recordings are saved, the system has to record 100% of the time into a ring buffer so that the situation leading up to the trigger is saved. The Saloon cameras really need to record all the time as the driver may be unaware of am 'incident' in progress and be able to manually trigger a save. And a 'passenger altercation' won't trigger any of the sensors.

I would assume the camera's record 100% of the time the tram is turned on.

They may or may not record audio - that would be the policy of the operator to decide.

Thoreb C90 (also used on a lot of buses for engine monitoring) can do cameras. The Variotrams were fitted with Thoreb C90s late in their life - but only configured to run the destination displays and voice announcements. None of the other advanced functions of the Thoreb system were used. The Thoreb had it's own GPS receiver for triggering the station announcements and had a connection to the door enable circuit so it knew when the doors were open.

So as withdrawn, the Variotrams had 3 GPS receivers!. One for the MDVR, and one on each Thoreb C90 (each cab had it's own system).

So the question of what and when the E class cameras save video would be in a Yarra Trams policy document somewhere.

On the E class the recorder is probably intergrated into the train management computer. This also appears to be the case on both the Urbos 3 and the Citadis 305s.