Why are there expansion gaps in bridges?

Expansion gaps are provided in bridges to allow for thermal expansion and contraction of the bridge deck. As the temperature increases, the bridge deck expands, and the expansion gaps provide space for the deck to expand without causing damage to the bridge structure. Similarly, as the temperature decreases, the bridge deck contracts, and the expansion gaps allow for the deck to contract without causing damage.

The expansion gaps also accommodate any movement of the bridge deck due to traffic loads, wind, or other environmental factors. By allowing for movement, the expansion gaps help to reduce stress on the bridge structure and prevent damage.

The width of the expansion gaps is determined based on the expected range of temperature variations and the length of the bridge deck. The gaps are typically filled with a compressible material, such as rubber or asphalt, to prevent debris from entering the gap and to provide a smooth transition for vehicles crossing the bridge.