Holding the line
Question: How do welded railway lines, with no gaps, cope with expansion and
contraction in different temperatures?
Answer: Older rails buckled in hot weather once they had expanded to fill the
gaps between them. Welded rails are laid down under tension, by being stretched,
so a rise in temperatures causes only a drop in the tension. With no need for
gaps, passengers have a smoother ride. But if the temperature continues to rise
after the tension has dropped to zero, the rail will buckle, just like the old
type.
Barry Lord
Rochdale
Greater Manchester
Answer: In the…
