Cattle generally can't in North America…old engines had "cowcatchers" that actually did push wayward animals off the track when the engine hit them, but in the UK some years back a train between Glasgow and Edinburgh (IIRC) hit a cow and was derailed.
What would cause a train to derail?
A derailment is when a train runs off its rail, either because of a collision with another object, a conductor error, mechanical track failure, broken rails, or defective wheels. A derailment doesn't necessarily mean the train leaves the tracks – some may be minor.
Is it possible to derail a train?
Derailments can be caused by outside force damage such as a tree or debris on the track, a grade crossing collision, or a washout of the rail bed,” Allen said. “There may be a mechanical issue such as a flaw in the wheel, bearings, or trucks.
Can cattle derail a train?
What stops a train from derailing?
One way to prevent train derailments is making sure train wheels and bearings (the component that keeps wheels turning smoothly) don't overheat. Railroads do this by installing sensors along their tracks that assess the strength and health of wheels and bearings passing over them.
Can a piece of metal derail a train?
Yes. A huge and heavy iron bar/rod can certainly derail a train. The iron bar must be sufficiently heavy so that it is not easily crushed or pushed aside by the engine.
How do train tracks not buckle?
The steel rail on a railway track is a very long piece of metal that can expand or contract significantly in the summer and winter. This generates forces that try to push and pull the railway out of shape. The mass of the sleepers and ballast are designed to contain these forces and prevent the track from buckling.