America’s Federal Highway Administration (FHWA) oversees the maintenance, inspection, and repair of the thousands of public bridges located across the country. The official public bridge count across all 50 states, the District of Columbia, and Puerto Rico numbered 467,514 by 2014 according to FWHA records. National Bridge Inspection Standards (NBIS) regulate bridge upkeep and require that bridges be inspected every 24 months. These strict standards necessitate huge efforts and ample manpower in order to perform required inspections and ensure bridge upkeep. The challenges of bridge inspection are formidable, but today’s engineers are working to improve the way we perform bridge inspections in America. Read on to learn about a few of the biggest challenges as well as the ways the bridge inspection process might soon improve.
Bridge inspections can be impaired by the amount of expensive equipment sometimes required to perform them. While some bridges can be inspected on foot and with simple tools or equipment, others require more substantial aids. Dive teams are often necessary to thoroughly inspect a bridge with underwater supports. And in order to effectively gauge the condition of the underside of a large bridge, suspension rigs or under-bridge-inspection-trucks (UBIT’s) are necessary to allow access. Watercraft can sometimes be necessary, as well as large lights, scaffolding, or electronic equipment. The ownership and maintenance of all these equipment types incurs additional work and expense.
Lane Closures and Traffic Disruption
Because all of the bridges that the FHWA maintains are also public roadways, traffic must be considered when planning a bridge inspection. Depending on the location and design of the bridge, traffic might even have to be rerouted or stopped in order to perform the inspection properly. This can cause delays, complaints, or potential traffic hazards. Traffic control often also necessitates the involvement of local law enforcement.
Dangers to Personnel
Inspecting bridges can be quite dangerous (Minnesota’s Department of Transportation, Bridge Inspector’s Reference Manual, 2.2.1). In addition to inherent dangers that can include being suspended from significant heights, moving around and over potentially unstable structures, and working in and around water, personnel are regularly exposed to outdoor elements, inclement weather, traffic, and more. Significant training is required to ensure safe working conditions for bridge inspectors to minimize risks.
Varying regulations affect bridge inspection procedures. Bridge inspection must be performed in ways that will not disturb endangered and protected fowl migration and nesting periods. Inspectors must also keep current on other protective environmental measures, such as for water or plant life, to avoid compromising or damaging protected flora and fauna during their inspection efforts. Regulations also stipulate other aspects of bridge inspection including managing personnel qualifications, controlling scheduling procedures, requiring thorough recordkeeping, and more.
As with any type of manmade structure, bridges weaken over time and their structural integrity can be compromised by a wide variety of incidents and problems. The National Bridge Inventory (NBI) contains more than 1,700 bridges that were built before 1900, and more than 250,000 bridges in the inventory that were built before 1980 (FHWA). Even discounting events such as natural disasters, weather-related damage, and traffic incidents, natural wear and tear will compromise a bridge over time and necessitate repair or even its removal and rebuilding. Wooden structures can rot or suffer damage from insects or animals. Metal structures can rust or erode. Underwater components can shift or suffer structural weakening because of aquatic wildlife such as barnacles or plant growth. Electronic components of any bridge can be compromised by water damage, storms, electrical shorts, power surges, tampering, or any number of other issues.
Future of Inspections
To combat the challenges of keeping aging bridges across the country sound, competent engineers and infrastructure professionals, along with researchers and developers, are devising ways to make bridge inspections easier, safer, and more accurate. Robots – including hose being developed in university settings — can now perform many prior manual functions (Bridge Inspector’s Reference Manual, 2.4.11). For example, robots can access dangerous or out-of-reach areas, and collect pictures, measurements, samples, or video to be analyzed by inspectors and engineers.
However, many aspects of a current bridge inspector’s process could be vastly improved by available technology. Note taking and report writing can be much improved by digital collection. Tablets can make it possible to save pictures, upload results instantly, and disseminate reports electronically. GPS technology is beginning to appear in bridge inspection procedures, along with sophisticated software and laser scanning that creates and maintains computerized bridge models. These and other advancements will help enable bridge inspectors and engineers to more effectively and safely maintain America’s bridges.
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