Can someone with more direct train knowledge provide information or speculation on the following:
http://www.cnn.com/2013/07/10/world/americas/canada-runaway-train/index.html?hpt=hp_t1
Nine black tanker cars filled with crude oil still stand silently in the town of Nantes.
They remained behind when the rest of the train they were attached to broke away and began rolling early Saturday down an incline, seven miles uphill from Lac-Megantic.
...
His engineer reported having deployed the hand brakes on a number of tanker cars and on the engines. The brakes on the locomotives eventually held, he said.
They stopped a quarter of a mile away from their original parking spot in Nantes, he said. They did not make it to Lac-Megantic.
He could not explain what happened with the brakes on the 72 oil cars that did.
- - - - - - -
Please ping those that might be able to explain more how cars might separate in such an event.
I don’t believe that there are any normal circumstances that would cause the cars to break away from each other. The couplings must have been released. I’m thinking teenagers pulling a tragic prank.
The train was parked near the top of a ~1% grade. One locomotive was left running and the regular (whole) train brakes were left on (air pressure from the loco's compressor to make up for the normal leakage). The locomotive brakes were likely applied in some fashion. The mechanical "park" brakes on a few tanks cars were set in some fashion. The (one man) train crew caught a cab to town for the night.
The front locomotive had a fuel leak and the locomotive caught fire.
A Nantes resident was driving by and saw the fire. Nantes FD was called. They shut off the locomotive per procedure and put out the fire. The Nantes FD contacted somebody associated with the railroad. One or more RR reps showed up. The FD left. The RR reps did who knows what and left.
Eventually the brake forces reduced and the train started to move.
By the time the train reached Lac Megantic it was doing something like 40 to 60 mph. The train entered the town's rail yard where the typical speed is 10mph to be able to negotiate the switches and curve.
At least the locomotives and maybe some tank cars made it through the yard. Approximately 50 cars derailed near the first switch and piled into each other disconnecting from the front of the train which kept going. 9 to 13 cars at the end of the train remained on the tracks.
Ruptured tanks spread the crude which caught on fire from some unknown ignition source. The fire swept through parts of the town as some of the crude flowed downhill towards the lake.
The intense fire at the pileup caused 4 to six of the tank cars to achieve a BLEVE explosion.
During the fire the engineer (who was now in town at his hotel) grabbed a rail car moving vehicle and removed the intact tanks cars from the rear of the train and pulled them away from the blaze. A day or so later the RR came and hauled the 9 to 13 intact tank cars back up to Nantes.
The locomotives and possibly a few tank cars came to a stop somewhere on the other side of town as there were still brakes applied, the grade was now level or rising and the mass of the train was now much less.