What is the primary inspection method for detecting surface defects on bridges?

Visual inspection is the primary method for detecting surface defects on bridges due to its accessibility and efficiency. This technique allows inspectors to visually examine structural elements for obvious signs of deterioration, such as cracks, corrosion, and deformation. Conducting a visual inspection requires minimal equipment and can be performed quickly, making it ideal for routine assessments and initial evaluations. Inspectors can also assess the condition of protective coatings and the overall cleanliness of the structural components.

Other inspection methods mentioned, while useful in certain contexts, serve different purposes and often involve more complex procedures. Ultrasonic testing is effective for detecting subsurface flaws rather than surface defects. Load testing evaluates the structural capacity and performance of a bridge but does not directly reveal surface defects. Radiographic inspection is primarily used for detailed examinations of welds and structural connections, focusing more on internal features than on surface conditions. Therefore, visual inspection remains the first line of defense in identifying surface issues on bridges.