Why are hinges sometimes included in arch bridge designs?

In bridge engineering, hinges are sometimes incorporated into arch bridge designs specifically to reduce stresses caused by the expansion and contraction of materials due to temperature changes.1

By allowing the structure to react to varying temperatures, these hinges prevent the buildup of detrimental internal stresses that could otherwise compromise the integrity of the bridge. While modern arches made of materials like steel or concrete are often highly rigid, the use of hinged intersections allows different parts of the arch to work independently, providing engineers with greater flexibility in design and the ability to manage forces across large spans.12