Why do engineers design bridges with expansion slotsions?

Bridges are designed with expansion slots to allow for the expansion and contraction of the bridge deck due to temperature changes. When the temperature increases, the bridge deck expands and the expansion slot allows the bridge to move without causing any damage to the structure. When the temperature decreases, the bridge deck contracts and the expansion slot allows the bridge to move back to its original position.

The expansion slots are typically made of a flexible material such as rubber or steel, and they are located at regular intervals along the length of the bridge. The size of the expansion slots is determined by the expected amount of movement that the bridge will experience due to temperature changes.

Bridges are also designed with expansion slots to allow for the movement of the bridge deck due to other factors, such as wind, traffic, and earthquakes. By allowing the bridge deck to move freely, expansion slots help to protect the bridge from damage and extend its lifespan.