On 26/10/20 10:38 am, 'Brent Efford' via TramsDownUnder wrote:
> I assume Canberra will have trams fitted with adequate battery power by the time the wireless section through the Parliamentary precinct is inaugurated, eliminating the potential unreliability associated with dependence on a centralised overhead (or APS) power supply.
Central power failure stopped the service, but another systems failure was responsible for the 'tapped passenger' incident.
> In Wellington, overhead supply failures in both the light rail-like suburban railway system and the former trolleybus system accounted for most of the wide-area service disruptions over the years. Far more significant as a service disruptor than rare battery fires which affect only individual vehicles.
The failure that 'trapped' people on board was a software systems failure on the tram itself that took out the passenger-driver intercom, so the passengers could not speak to the driver. The loss of a substation and overhead power
triggered the situation, but it was not the cause on it's own.
It appears no one twigged to operate the electro-mechical door override next to the door. They just keep pressing the non functional pass-com alarm button.
And the Sydney trams concerned have traction batteries - the un-contained failure of one set being subject of an open ATSB investigation.
The Sydney Citadis are more than capable of running on battery power to the next passenger stop and 'de-tramming' passengers in a controlled manner. They apparently have approx 500m range on battery. Most modern trams have at least the option for 'limp to more appropriate location' battery mode on loss of overhead power. I've watched (and have video) of a Gold Coast Flexity moving 50m out of siding with the pantograph down.
At least once 'incident' on the CESLR appears to have been a driver accidentally hitting the 'switch to battery mode' button at Town Hall instead of the 'switch to overhead power mode. (The buttons are adjacent) and then conking out some where down the southernern end of George Street when the battery ran down.
A properly engineered and operated tramway (and trolley bus) overhead system has very few failures. It's these modern systems with extensive SCADA systems that micro-supervise everything that seem to have the most problems. How often does Melbourne have a line shutdown due to a large scale power issue ?.
Even Sydney's over engineered system has mostly settled down now. The ongoing 'issues' are operational, not the hardware. (Particularly incident response and 'degraded mode' operations)