Q. Why is a small space left at the joint between the two rails?
![](https://syskool.com/wp-content/uploads/2014/02/Expansion_joint_Hayle-1024x768.jpg)
![](https://syskool.com/wp-content/uploads/2014/02/Bordeaux-aps-isolationampjoint-1024x731.jpg)
A. Metals expand on heating and contract on cooling. A small space is left between each set of two rails of the railway line to allow for their expansion in summer and contraction in winter, respectively.
![](https://syskool.com/wp-content/uploads/2014/02/figure_10.png)