What ballast does beneath the sleepers
The crushed stone under a railway sleeper must hold the track in place while leaving water a way out. Its condition can change a line's geometry long before the rail itself wears out.
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Why a train wheel has a different shape from a car wheel
A railway wheel does more than roll. Its tread meets the rail at changing radii, while its flange waits beside the rail; together with the fixed axle, those shapes help a train follow curves and stay stable on straight track.
The timetable hidden inside a passing loop
A passing loop is a brief stretch of double track on a single-track railway. Its location and length decide where trains can meet, how timetables fit together, and how delays spread.
How steel rails make room for summer
Long welded rails have few expansion gaps. Their summer margin lies in a chosen neutral temperature and in the fastenings, sleepers and ballast that hold them straight.