The structure of a bridge can become unusable not only due to deterioration over time but also due to increased loads or larger clearances that are required later on. The structural design must also include such future demands.
Bridge maintenance authorities must keep records of periodic inspections and repairs. Such records help to assess the structural condition for the planning of timely rehabilitation measures, generally in large structures such as bridges, power plants, and public buildings. There are many companies that provide drawbridge inspection services and they are very experienced and professional in their work.
The state or large houses, for example, have good maintenance programs compared to bridge structures with a multitude of private owners such as residential flats.
The inspection includes routine and detailed work. The first involves visual observations of various components and simple on-site testing. Binoculars and digital cameras are used for routine inspections and specific equipment for detailed work.
A full inspection requires close access to a highly structural component by means of specially designed equipment or ancillary equipment (scaffolding, ladders, and seat belts). Adequate clearances, 1.2 m horizontally and 2 m vertically, should be provided to facilitate the movement of personnel. Special inspection carts will be needed to provide access to the bridge components above ground level. The safety of inspection personnel must not be compromised in any way.
It is recommended that bridges be inspected on rainy days for cracks, leaks, and blockages to the drain. Inspection at different times of the year is also essential to observe structural performance in all weather conditions.