What is the main reason for weight limits on bridges?

Weight limits on bridges are primarily established to prevent structural failure. Bridges are designed to support specific loads, which include the weight of the bridge itself, plus vehicles and other loads that may cross it. Each bridge has an engineering design that can handle a certain maximum load without risking damage or collapse. When vehicles exceed these weight limits, it can cause stress on the materials and structural components of the bridge, potentially leading to failure.

Maintaining appropriate weight limits is essential for ensuring the longevity and integrity of the structure, protecting both the bridge and those who use it. The safety of both the bridge and the vehicles crossing it depends on adhering to these limits. While other considerations such as traffic flow, vehicle safety, and maintenance costs are important, they are secondary to the bridge's structural integrity, which is the primary concern when it comes to weight limits.