Derailment

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A derailment is when a train comes off its rails. It can disrupt service and is a serious safety hazard. Derailments are usually caused by one or more of these: a broken rail or weld, track misalignment or buckling, excessive speed on a curve, problems with wheels or axles, or an obstacle on the tracks (like a vehicle at a crossing or, rarely, an animal). In some cases, safety devices at track exits are meant to prevent bigger accidents.

History and scale: The first recorded derailment happened in 1833 in New Jersey. Derailments were common in the 1800s, but safety improvements have reduced them. In the United States, derailments have declined over the decades, though they still occur. High-speed derailments often grab attention when a curve is taken too fast.

How a derailment happens (simple explanation): On curves, wheels follow the curve, and if the rail or wheel is worn, or if the curve is too sharp or the train speeds up too much, a wheel flange can climb onto the rail head and the wheel can leave the track. Other failures, like broken rails or weak track joints, can also push a train off the rails. Large forces between cars, poor maintenance, or an obstacle can contribute too.

Safety measures and recovery: Railways use devices like trap points and derails at sidings to keep trains from leaving the main lines. After a derailment, crews pull or lift the derailed cars back onto the track with ramps, jacks, or cranes. If the train is badly positioned, parts of the track may need repair or replacement, and authorities may pause service in the area.

Notable examples:
- Hightstown, New Jersey, 1833 — the first recorded derailment.
- Hatfield, England, 2000 — rolling contact fatigue led to a derailment.
- Eschede, Germany, 1998 — wheel tire fracture caused a high-speed derailment.
- Polmont, Scotland, 1984 — a cow on the line contributed to the crash.
- Salisbury, England, 1906 — a locomotive overturned on a sharp curve.
- Overspeed incidents on curves: Santiago de Compostela (2013) and Philadelphia (2015) involved trains going too fast on curves.

Prevention and ongoing improvement: Regular track maintenance, improved rail and wheel design, better testing and inspection, and modern signaling and control systems help reduce derailments and catch problems before they cause accidents.