What might be a sign of a serious defect during a bridge inspection?

Visible cracks in the structure can be a significant indicator of a serious defect during a bridge inspection. Cracks may suggest various issues such as deterioration of the materials, structural fatigue, or excessive loading. Understanding the extent, location, and nature of these cracks is imperative, as they can compromise the integrity of the bridge.

For instance, wide cracks or those that develop over time can indicate structural problems that require immediate attention. Inspectors often assess the size, direction, and propagation of these cracks to determine whether they represent a critical safety concern. Identifying and addressing cracks early in the inspection process can help prevent further damage and ensure the safety of the structure and its users.

The other options mentioned, while they might be observed during an inspection, do not inherently indicate a serious defect in the same way. Vegetation may affect aesthetics or drainage but does not directly signify structural issues. Graffiti, while it could indicate neglect, does not reflect the physical condition of the bridge itself. Traffic delays might be due to various external factors and do not provide specific insight into the structural integrity of the bridge.