If a continuous railway track is used for railway lines, the track will buckle when temperature rises. This will cause a train to derail. To prevent this, small gaps are left between sections of the iron rails. These allow the tracks to expand in hot weather.
Electricity cables and telephone wires
On a hot day, electricity cables and telephone wires expand and sag. In the early morning or at night, the temperatures are low. Cables and wires contract and tighten. Electric cables and telephone wires are hung loosely to allow for expansion and contraction.
Usually, one end of a bridge is fixed. The opposite end rests on rollers. There is also a sliding joint at the moving end. When the metal bridge expands or contracts, it is not damaged.
Concrete road surface
If concrete road surfaces and pavements were laid down in one continuous piece, cracks would appear. Road surfaces and pavements expand and contract because of changes in temperature. To prevent cracks, small sections or tiles are used. The gaps between these sections are filled with a soft material. On a hot day, the tiles expands and squeeze the material so that the concrete road surfaces and pavements will not crack easily.