Michael R N Dolbear wrote:

"MB" wrote

It's too easy just to check you can see a picture from the camera and
assume it is recording.

Which is why there needs to be a system in place to check at some
regular interval that they are recording and that the recordings are
archived properly with that being logged.

The interim report says
Initial analysis of the tram’s OTDR indicates that some braking was applied
in the 180 metres before the 20 km/h (12.5 mph) speed restriction board, but
this was only sufficient to reduce the tram’s speed from 80 km/h (50 mph) to
approximately 70 km/h (43.5 mph) by the time the tram passed the board and
entered the curve on which the accident occurred.
==
And
The RAIB’s ongoing investigation will include consideration of:
{. . .}
l any previous over-speeding incidents at Sandilands Junction;
==

Does this mean that trams' OTDR (and CCTV) data are archived so, eg, any
report of possible over-speeding can be checked against real data on this
and on normal running?



Mainline practice is that the vehicle's OTMR stores the data for as long as
it can; it's basically always full and deleting the oldest data at the rate
that new comes in. In practice I think that's around 2-3 weeks for plain
OTMR data, presumably those fitted with CCTV have larger data storage
devices?

When a vehicle is downloaded (for fault finding, assessment or
post-incident) afaik the whole file is then kept and made available for
other authorised uses. If a download is not taken, then once the info times
out on the vehicle's data recorder then it's lost.

Tramway practice may be different.


Anna Noyd-Dryver