Forty-two people were confirmed dead, with five more missing and presumed dead.[3] More than 30 buildings in the town's centre, roughly half of the downtown area, were destroyed,[2][4] and all but three of the thirty-nine remaining downtown buildings had to be demolished due to petroleum contamination of the townsite. https://en.wikipedia.org/wiki/Lac-Mégantic_rail_disaster

Anyway rail transport of oil through populated areas is also a major risk. Which is why it’s also banned in some places.

Transport of oil through populated areas is quite common. Local governments that have restricted its transport are welcome to do the same for LNG.

Do some math and even just a single 35,000 gallon tanker load is going to flow around like a liquid for quite some time.

Let’s say 10 tanker cars so 350,000 gallons or 560,000kg are spread down a water channel at the side of a street at 15mph. At 4 minutes their already covering 1 mile which easily takes them out of most towns making longer durations largely meaningless. If the channel is V shaped with a depth of 2 feet and a width of 10 feet. That only adds up to ~4,5000 square meters, and by your calculations most of it should still be there.

It doesn’t last as long if it’s on fire, but there’s going to be an air gap of unmixed natural gas over a likely several feel thick channel of LNG. So even then it’s going to take a while to burn off meanwhile the wave of fire is destroying everything around it.

In a real scenario, the cars are going to be spread out over an area, their ruptures will be relatively small orifices that the fluid must flow through, it's going to spill out rapidly in all directions from that point, any area where a train is passing through is going to be decently wide and flat, worst case scenario probably a 50 foot wide street.

You can look up pictures of derailed tanker cars, for example [0], and see the area where the liquid spills over. By the time the contents of a tanker car have spread over an area of 1 acre, the fluid is only 1in deep, even if none of it vaporizes it's limited in how far it can meaningfully spread. The spill of a cryogenic fluid will by necessity cover less area. As you can see, the spill of 322,000 gallons of flammable liquid affects an area comparable to that threatened by the derailed train cars themselves. That fire lasted 36 hours, wouldn't it be great if all the fuel evaporated in 36 minutes?

[0] https://www.progressiverailroading.com/federal_legislation_r...

And speaking of lumber: https://bangordailynews.com/2020/07/29/news/a-scene-from-hel... (I need a better link, but basically the cars with hazardous material did not leak, and the fire was from lumber.)

Surprise surprise, Lumber is actually more dangerous than LNG! Because none of that would have happened with LNG. With LNG it all dissipates very fast.

32 dead because of derailment of LPG transporting train. Is the hazard posed by LPG much different to LNG?

LNG rises up into the air and is gone.

It seems to me that it could, but I am not an expert. Natural gas has a smell added because it has historically exploded...

> If you are comfortable with oil being transported through densely populated areas, you should be fine with this.

What if I'm not comfortable moving crude but train?

Natural gas is an explosion hazard in enclosed spaces. If you walk into your house and smell gas, that's very dangerous. Note also that even if there is no explosion hazard, fire is still dangerous.

If you are uncomfortable with rail transport of crude, that's a perfectly legitimate stance to take. Honestly, transporting any flammable substance (and many non-flammable ones as well) does pose risks. If you know the risks and benefits and think the former outweigh the latter, let people and especially your representatives in government know. However, society generally seems to accept rail transport of oil and similar chemicals, so outrage over the transport of a less dangerous substance seems like it would be more likely to come from a place of ignorance than rational analysis.

> Ray Mentzer, a chemical engineer at Purdue University, spent his career working on LNG projects for Exxon Mobil. He says the specially designed containers that transport hydrocarbons have a good safety record. But he says transporting the gas through densely populated areas increases the risk if there's a leak.

> "It's not flammable until it's vaporized, but it's going to be vaporized pretty darn quickly and then it's going to seek an ignition source," he says. "Believe me, it will find an ignition source pretty darn readily."

I will also note that those train tracks in the town in the photos had a derailment only a few years back. I am familiar with the area and know people who live there.

https://response.restoration.noaa.gov/about/media/train-dera...

I would also note that the engineer's use of informal language here is clearly alarmist.

Well yes, but actually no.

You can't get a freight train up to the kind of speed you need to create an "instantly dump the contents of the pressure vessel" type crash without creating a "slowly vent the contents out" type crash first.

You would need to use a bomb to rupture a pressure vessel to get the kind of fuel/air mix you need for an explosion or fireball. Fuel-air explosives operate in this manner. But they are devices with countless engineering man-hours spent making them actually work and fairly precise manufacturing. Parking ye ol' Winnebago (or Penske, if you're a history buff) beside the tracks and waiting for the train to go by is not going to be a very productive approach. Look at people blowing up propane tanks on YouTube. At best they get a fireball.

I'd much rather have nat-gas wafting up and away rather than crude oil, propane, or some other volatile that sits at ground level.

Lighter-than-air gas is crucially different. If you let that leak out it won't flow downhill through the city, it'll go straight up. Of course you can argue that gas is dangerous, but not by example of an accident where most of the flammable material flowed away (and caused harm elsewhere) instead of either burning or exploding at the site.

Again it’s a question of scale, you don’t think of say molasses as fast moving liquid but increase the scale to 2.3 million gallons and you can be talking about a 25 foot tall 35 mph wave. https://en.wikipedia.org/wiki/Great_Molasses_Flood

You can't have your cake and eat it.

Read up on how you can get temperature inversion layers in the atmosphere. In your model that kind of effect shouldn’t happen, but actual fluid dynamics gets complicated.

Or were you thinking about transporting LNG together with something that that would help start a fire?

At which point those secondary fires can easily ignite the literal pools on LNG being described.

Would you describe this as a noticeable risk compared to driving around in a car, in urban traffic, with gasoline? Or are you comparing it rather to an alternative that more or less avoids transport of LNG?

I think the worry is that the volume of shipments for LNG would be much higher, and hence the probability of something happening is higher. A singular shipment of LNG would be no worse than a single shipment of car gas.

Any such aerosolization would rapidly go up into the sky.

It would make a fire, but not a disaster.

Here is a PDF with seems to have the longest url I've ever seen: https://pdf.sciencedirectassets.com/278653/1-s2.0-S187770581...