Why are there gaps in bridges?

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As I pass by the Mactan-Mandaue Bridge yesterday, I noticed those little gaps in the bridge. I researched about the gaps and what could be the possible reason behind these. Upon reading few of the articles found in the internet here are some of what I learned about it.

The gaps in bridges are called "Expansion Joints" or also known as "Movement Joints" .
These joints are not only present in bridges but on several sections in buildings, sidewalks, railway tracks and other structures as well.

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The main function of the expansion joints is to allow the road to contract or expand when the temperature changes. For example, when seasons change, the concrete slabs expand or contract depending if it is warming or cooling.
Also,structures made of concrete may contract or expand due to shrinkage of concrete and also due to settlement.
Without the expansion joints, the structures would crack because of the stress acting.

The bridge expansion joints pave way for the concrete to naturally expand and contract without cracking.Where can they be observed, you may ask? The expansion joints are commonly placed at the end of bridges to the place where it meets up with the freeway. In short, these expansion joints help give the Mactan-Mandaue bridge a little room to breathe, an allowance perhaps.

I hope this gives you clarity about it! If you have informations to add, feel free to leave a comment below!