Some examples are
1. The railway tracks over which a train runs are made of iron. During summer, the iron expands. To allow this expansion, space has to be left between two sections if rails. If this is not done, expansion of tracks can cause them to bend. This can cause serious accidents.
2. In similar way, in steel bridges, one end is made to rest on rollers, with enough space provided for expansion during summer. If this not done, accidents can occur.
