Saturday June 02, 2007

Fiery crash collapses Bay Area freeway

news.yahoo.com (backblog) :

A gasoline tanker crashed and burst into flames near the San Francisco-Oakland Bay Bridge on Sunday [29 Apr 2007], creating such intense heat that a stretch of highway melted and collapsed. Officials predicted a traffic nightmare for Bay Area commuters for weeks or months to come. Flames shot 200 feet in the air, but the truck's driver walked away from the scene with second-degree burns. No other injuries were reported in the 3:45 a.m. crash, which officials said could have been deadly had it occurred at a busier time.

Nearly 75,000 vehicles a day use the interchange. But because the accident occured where three highways converge, authorities said it could cause commuting problems for hundreds of thousands of people. 280,000 commuters take the bridge into San Francisco each day.

The tanker carrying 8,600 gallons of gasoline ignited after crashing into a pylon on the interchange. A preliminary investigation indicated the driver may have been speeding on the curving road. Witnesses reported flames rising up to 200 feet into the air. Heat exceeded 2,750 degrees and caused the steel beams holding up the interchange from eastbound I-80 to eastbound Interstate 580 above to buckle and bolts holding the structure together to melt, leading to the collapse. The charred section of collapsed freeway was draped at a sharp angle onto the highway beneath, exposing a web of twisted metal beneath the concrete. Officials said that altogether a 250-yard portion of the upper roadway was damaged.

- As you can see, I'm still ploughing through the considerable "backblogs".

As an off-topic thing (and as a peakoiler and all-round energy geek), I was trying to calculate and compare the energy output of the resulting explosion with the potential energy contained in fictional laser blasts from let's say, a Mech from MechWarrior or a Herc from Starsiege.

Here it goes : let's assume that all 8600 gallons of gasoline burnt and went up in smoke and most of the energy went into melting the highway. There is 8.8 KWh of energy in each litre of petrol (what the UK-affiliated parts of the world call gasoline). And, according to Google, 1 US gallon = 3.7854118 litres. So we have a total of 286480 KWh (kilowatt-hours) of energy there, let's divide by 1000 to put this into megawatt-hours, that will be 286 MWh.

Now, I vaguely recall that a "typical" particle-beam weapon (PBW) requires about 400GW of energy to fire. These giant robots are assumed to have big fusion reactors and huge mega-capacitors, but hey that's science fiction, anyway (for now). I also vaguely recall that I needed perhaps 2 or 3 shots to take down "typical" un-armoured civilian structures (buildings, hangars, and perhaps highway intersections??). Each shot took about 1 second. So the amount of energy = 400 GW x 1 second = 400 x 1000 / 3600 MWh = 111 MWh per PBW shot.

So, to melt the highway bridge, it does require 2 or 3 shots (222-333 MWh) from a particle-beam weapon, comparable to the 286 MWh released from the burning gasoline.

Okay, you can call me crazy now :)

(2007-06-02 12:20:14 SGT) [Energy] Permalink

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