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The San Bernardino train disaster happened on the morning of May 12 1989 in San Bernardino, California A Southern Pacific freight train (SP 7551 East) ran away down the Cajon Pass before derailing and ploughing into a residential area on Duffy Street.• The total property damage was $14.3 million. Many residents moved out after this, and homes are no longer allowed to be built next to the railroad lines.
The accident was featured in an episode of the Crash Scene Investigation documentary series, shown on National Geographic channel in 2006.
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Cause
The train was carrying trona (a material used to make fertilizer) that had been mined and loaded onto the freight cars for shipment to a buyer. The buyer had purchased 6900 tons of trona; thus the mining company contracted for 69 100-ton hopper cars. When the mining company turned in the final contract to the clerk for the bill of lading, they had not filled in any weight, assuming that the railroad would know that they had filled the 100-ton cars to capacity. The clerk filled in the bill of lading as 60 tons per hopper car, going by a visual comparison of 100 tons of coal. As a result, the train was listed as significantly lighter than its actual weight (Warren, 3).
Engine 2 of the first four engines did not have any dynamic brakes, just air brakes. Engine 6 (the last one of the two helper engines in the back) also did not have dynamic brakes. This information about the last engine was not passed on to the lead engineer. Thus, he had faulty weight information and faulty information about his braking power to work with when calculating his maximum descent speed down the steep mountain pass. When he realized that the train was gathering too much speed, he did all he could to brake the front engines and asked the helper engine engineer to do as much as he could to help also (not knowing that he had only one working engine braking in the back). As a last chance to stop the train, the helper engineer activated the emergency brake, unfornunateley this disabled all the dynamic brakes on the train, allowing the train to pick up speed. After the activation of the emergency brake the only brakes which were operational were the air brakes which were melting. The train reached a speed of 110 miles (177 km an hour) on a curve at Duffy Street designed to hold the train at 40 mph. At that speed and with the friction of the brakes, the wheels were actually turning molten when the train left the track in its destructive crash.
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