The purpose of a Bridge Inspection is to provide an unbiased, thorough examination of the structure, equipment, and infrastructure of a structure that links two or more locations. An inspection will reveal any problems with the structural integrity of the structure as well as to detect potential problems that could pose a threat to public safety. Inspectors perform routine inspections, as well as preventive audits.
Bridges are inspected periodically to determine whether they are in need of repairs, or if they are safe to operate. An inspector will inspect bridges in their functional status (functioning properly) as well as make recommendations for bridge maintenance based on visual examination of the structures. In addition to inspecting bridges for functionality, bridges are inspected for safety, load-bearing capacity, and structural integrity.
A bridge inspection will begin with a visual examination of the structure by the bridge inspector. This includes a complete examination of the infrastructure, such as signage, emergency lighting, and emergency telephones. Next, the bridge inspection will move towards the actual structure, including an assessment of the structure's structural integrity. The bridge inspector is trained to look for cracks, buckles, and other signs of damage, which may be indicative of a structural issue.
Most inspectors will perform some type of preventative maintenance inspection each year. These inspections are usually focused on improving highway and bridge conditions and practices. Preventive inspections help to reduce the occurrence of costly mechanical failures. Preventive inspections are typically performed every two years. However, many bridge inspectors do not perform these inspections due to the costs, time restraints, or the knowledge that most problems do not occur until much later.
An important part of the bridge inspection process is the observation of the truck traffic as it enters and leaves the particular area being inspected. It is very difficult to drive a large vehicle in any traffic pattern without being monitored by one or more traffic monitors. Traffic monitors are trained to observe all aspects of passing trucks. For example, if a truck is coming up on a bridge from the left, the snooper truck will stop and allow the truck to pass; if the truck is coming up on a bridge from the right, the bridge monitor will move out to ensure that no truck will hit the rear of the vehicle.
Drones could soon become an important part of the bridge inspection process. Currently, there are about 25 UAVs (unmanned aerial vehicles) currently in use across the United States. Some of these drones are used for mapping, surveying land, and for searching for buried utility lines. Drones have the potential to reduce the number of deaths and injuries associated with accidents on the highways, reducing the overall cost of repairing the roads and shoulders. A drone can also help to increase the efficiency of the highway by reducing traffic jams, increasing load forwarding and down-riding, and increasing overall vehicle control. All of these results are possible through the implementation of drones into the regular inspections of highways.
Non-destructive testing methods can also be applied to older bridges. Many older bridges were constructed using reinforced concrete. When the concrete fails over time, structural reinforcement is simply removed to allow access to the metal foundation that supports the concrete.
When a non-destructive inspection is conducted, the inspector typically completes two years of investigation before issuing an inspection report. The report usually contains recommendations to resolve the most pressing safety issues before issuing a report. Inspectors will often recommend that nothing be done to prevent the bridge from failing, however. If this recommendation is not followed, two years from the date of the last inspection (or the first year if the bridges are retrofitted) is usually required for bridges to be evaluated again.
