What is the primary reason for weight limits on bridges?

The primary reason for weight limits on bridges is to prevent structural damage and ensure integrity and safety. Bridges are engineered to support a specific amount of weight, which includes not just the vehicles themselves but also factors such as dynamic forces from movement, wind, and environmental conditions. When vehicles exceed the designated weight limit, it can lead to excessive stress on the structure, potentially resulting in damage or even catastrophic failure.

Exceeding these weight limits can compromise the materials and joints that hold the bridge together, leading to cracks, deformations, or overall weakening of the bridge. Therefore, maintaining weight limits is crucial to protect both the integrity of the bridge and the safety of all users, ensuring that the bridge remains safe for normal operation over time.