The bridge inspections process starts with the bridge inspectors reviewing the previous bridge inspection report and planning the inspection. The inspectors identify areas where defects were found in previous inspections. This allows them to determine if the defects previously identified have been repaired or have increased in size and severity. The inspectors coordinate traffic control and access equipment.
When the bridge inspection inspectors arrive at the bridge site they perform the bridge inspection from a distance. Some major problems may be indicated if the profile of the bridge is not smooth, in other words the bridge will not look right to the experienced bridge inspector. The inspectors will then concentrate on discovering the cause and determining the extent of the problem. Depending on the exact nature of the problem emergency repair or immediate closure of the bridge may be required.
The inspectors use a systematic method to inspect the bridge, to ensure that the entire bridge is inspected. The exact
order of the inspection will vary depending on the type of bridge being inspected.
The deck is the riding surface for traffic. The deck surface and road way barrier or parapet are looked at for potholes, cracking, excessive wear, and sounded for hollow areas. The deck joints are looked at for evidence of seepage, loose armor angles and if the deck joints are properly functioning to allow expansion and contraction as temperature changes.
The superstructure supports the deck and generally consists of beams or girders that may be constructed of timber, concrete or steel, and the bearings that connect the superstructure to the substructure. The inspectors pay close attention to areas of high stress and those prone to deterioration, but the entire superstructure is inspected.
Timber members are inspected for wood rot, crushing, splitting and cracking. Concrete members are inspected for cracking, spalling and hollow areas. (Spalling is where a portion of the concrete has fallen away leaving a hole in the concrete.) Steel members are inspected for paint peeling, corrosion and cracking. The bearings serve to transmit loads from the superstructure to the substructure and allow the movement of the bridge that occur due to changes in temperature.
The bearings during a bridge inspection are inspected for excessive deformation and evidence that they are functioning properly allowing the movements of the bridge due to temperature change. The substructure supports the superstructure and transmits loads from the superstructure to the ground. The substructure generally consists of pier caps, columns and piles. The substructure may be constructed of timber, concrete or steel. Timber members are inspected for wood rot, crushing, splitting and cracking. Concrete members are inspected for cracking, spalling and hollow areas during bridge inspection. Steel members are inspected for paint peeling, corrosion and cracking. In addition, the substructure is inspected for evidence of settlement or scour. Settlement is elements of the substructure move downward due to soil conditions. Scour is the undermining of a structure due to water flow removing soil which supports the structure.
The bridge inspectors’ actions will vary depending on their bridge inspection findings. The inspectors will recommend immediate closure or emergency repair of the bridge after the bridge inspection, if a critical condition is found that endangers the public. The inspectors will recommend a repair be performed quickly when a situation exists that if not addressed may lead to a condition that could endanger the public. The inspectors will recommend routine repairs or maintenance to correct defects that if not repaired could increase in size and severity and shorten the service life of the bridge.