Hacker News Reader

Comment by ShakataGaNai | Hacker News Reader

While this is unfortunate to have happened, this says more about CT being smart and having an over abundance of caution, than lack of faith in a technology.

BART, which has been running for 50 years recently [1] had an issue with the heat that caused a train to derail. For several days that section of track was totally shut down. For weeks afterwards they ran the trains at an extremely low speed through the miles of surrounding track - for safety. It's been a month and I'm honestly not sure if they are running "at speed" again yet.

It's good to be cautious when you don't know the cause of an issue or aren't sure what happened. Someone could have shot the bus's battery... or it could be wired in a faulty manner... or they could have a design flaw. Lots of options, good to ground them until you know why. Lest we have another MAX8 debacle.

[1] https://www.eastbaytimes.com/2022/06/21/bart-train-partially...

View on HN

Why don't we pull diesel bus fleets off the road whenever there is a diesel bus fire?

Complacency.

My take on 737MAX tragedies was lack of FAA diligence. Relocating engine mounts to squeeze in the oversized engines should have required the type certification process. Instead the FAA looked away and approved a software layer to make it seem similar to existing 737s so pilots could avoid re-training for what would be a new type certification.

That was regulatory failure while a bus battery fire could be a one-off manufacturing defect.

Yes. Good thing to ground them, but it also shows these vehicles are not ready. Even if its an act of sabotoge, like someone shooting at the battery. It would not happen with a regular diesel bus.

Umm, it did. In CT. Last month. https://archive.ph/FZ2wv

I think the difference here is that an EV battery fire quickly spreads to the entire length of the bus, because the battery spans the entire length of the bus internally. Whereas the diesel fire is contained to the fuel tank and engine block, which could allow passengers to more easily escape to whatever end of the bus isn't on fire.

New battery chemistries like LFP should solve the thermal runaway issue.

> I think the difference here is that an EV battery fire quickly spreads to the entire length of the bus

It's an interesting theory, but I don't see it supported by these articles.

The entire diesel bus had its back third engulfed very quickly, from these sources.

The entire electric bus burned, but we don't have any information on the rate at which the fire propagated.

If anything an EV should be possible to design to be safer against fires, as it's the battery itself that burns. A metal fire break on the floor and a gap between that and the battery should give warning signs (smoke coming out the sides) and give people time to evacuate before it becomes too serious. Temperature sensors throughout the battery could give warning signs even before it gets to that.

In an ICE vehicle it's the vapour of the fuel that burns. The engine of buses/coaches is typically under the floor, with access panels, so vapour can easily get into the cabin.

No, the bus batteries involved here do not propagate quickly. When it can't be contained, it takes more than 20 minutes to spread, which is plenty of time to evacuate the bus.

I don't see anything in this article about someone sabotaging the fuel line. In fact, they don't even mention how the fire started at all.

Why is this article relevant?

Here's the comment flow:

> Even if its an act of sabotage, like someone shooting at the battery. It would not happen with a regular diesel bus.

He's saying, even with sabotage, it would not have happened with a diesel bus.

Then a link was posted showing a diesel bus catching fire, no sabotage required. Diesel vehicle fires aren't some impossibility, as a quick google search will make clear.

Well yeah, you can forcibly set anything on fire if you want to, the comment was specifically referring to compromising the fuel system of the diesel vehicle, which we have zero information to indicate was the cause.

Shooting the battery pack won't cause the pack to do anything quickly. People would still have plenty of time to get out.

Reply on news.ycombinator.com