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The Lifespan of Structurally Deficient Bridges in America

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Have you ever driven over a bridge and wondered how old it was? In the United States alone there are more than 617,000 bridges, 12% of which are aged 80 years or older. But were all those bridges created at the same time or with the same method? What exactly is the typical lifespan of a bridge? And how many bridges are considered structurally deficient?

Contributing Elements to a Bridge’s Lifespan

Nowadays, bridges have become a natural part of everyday life. Your daily commute may even consist of traveling through a bridge or maybe two. Since they are vital to our economy and public safety, the government periodically mandates national bridge inspections to determine structurally deficient bridges.

Ultimately, there is no one number that fits the lifespan of all bridges across America. Each bridge has its own expected lifecycle but there are ways to estimate its lifespan. Generally, it’s believed that bridges are expected to function for 50-70 years however this is often not the case. Currently, only 42% of all bridges in the United States are at least 50 years old.

The lifespan of a bridge differs according to its design, construction, and location. Each component contributes either positively or negatively to the overall lifespan and structure of a bridge.

Materials

One of the most obvious factors that contribute to the lifespan and eventual structural deficits of a bridge is the material. In fact, both the concrete industry and the steel industry claim several advantages above the other for the Life Cycle Costs of a bridge.

Steel

Steel is a popular construction material due to its flexible and durable nature. The great thing about steel is that it is recyclable and still maintains its initial strength and integrity. Galvanized steel is even more durable plus it requires less upkeep.

Structural steel is a high-quality material that is readily available worldwide in certified grades and produced in various shapes and sizes. Currently, it is estimated that steel bridges have a lifespan of over 100 years. However, this number rapidly decreases as the bridge erodes or even with poor construction quality.

The deterioration of a bridge is created by a combination of several elements, for steel, it is often caused by corrosion, fatigue, stress corrosion, and damage from accidents.

Concrete

Another commonly utilized material is concrete. Concrete bridges are estimated to have a lifespan of over 100 years, again this number changes with daily wear and tear.

The causes of concrete deterioration are typically cracking, spalling, scaling, corrosion, and damage from accidents. In addition, cracks over reinforced steel allow water and chemicals to penetrate accelerating rusting which exerts great forces that pop the concrete.

Not to mention, extreme weather conditions, the presence of chlorides in de-icing salts, and cycles of freeze and thaw all contribute to the erosion of a bridge and its lifespan.

Timber

Timber, which is used for short-span and rural areas or pedestrian bridges is estimated to last only 20–30 years. This could be due to several reasons such as many engineers are less familiar with this material than their counterparts, or because there are fewer treatment options available for timber.

Nevertheless, the accurate range of which timber lasts is uncertain as there are very few data that exist that are based on actual performance data.

However, that doesn’t make timber a poor option. Timber is a lightweight material compared to concrete but still strong. This advantage plus low maintenance and repair costs make timber ideal in certain situations.

Plus studies suggest that timber is a durable option in highway bridge superstructures and that it can perform well for more than 70 years when properly pressure-treated with preservatives.

Location

The location of a bridge plays an instrumental part in its overall structural deficiency. Depending on the environment, it could accelerate the deterioration of the bridge.

Recently, there has been a slightly positive trend in addressing the maintenance of structurally deficient bridges. However, progress is not universal because states face different challenges when it comes to maintaining, repairing, and replacing bridges.

Urban

When it comes to urban locations, the major factor to watch out for is a higher traffic volume. The combination of a heavier load and volume further leads to the wear of the bridge. There are various ways for builders to slow this process down such as galvanization and other special treatments.

Rural

Unlike urban settings, rural bridges don’t have such a large volume of traffic. Unfortunately, it is because of this that rural bridges are typically not designed to withstand the growing numbers and weight of traffic and freight trucks. In actuality, rural bridges and transportation play a key role in our economy’s success and for rural communities.

However, more and more bridges in rural communities are experiencing rapid deterioration without the proper care and maintenance to last.

Coastal

Bridges that are located in coastal environments face unique challenges due to their location. Bridges in marine environments often experience corrosion-induced damage due to high sea salt and humidity. In addition, strength loss in the splash and the tidal zone is more common and significant than in the atmospheric zone.

An example of the distinct problems faced by coastal bridges is illustrated by the Morandi Bridge in Italy. In 2018, this cable-stayed bridge suddenly collapsed causing the death of 43 individuals. The collapse was reported as the fault of a weakened cable that deteriorated from corrosion. The degradation was caused by atmospheric agents and the proximity of the marine environment eroded the structure and integrity of the bridge.

Structural Deficient Bridges in America

Structurally deficient bridges are those that are in need of repair or maintenance due to the deterioration incurred throughout the bridge’s lifetime. Recently, 7.5% of highway bridges were designated structurally deficient. This is a striking improvement from the previous 12% record. In addition, the average age of America’s bridges is increasing to 44 years.

The plan is that the overall lifespan of a bridge should increase over time as more techniques, treatments, and designs are discovered in the future.

Build a Bridge that will Last Lifetimes with U.S. Bridge

Are you looking for an experienced industry leader company to assist with your building projects? Here at U.S. Bridge, we’ve built for different projects all across the globe; and we know that choosing the right material for your bridge takes a combination of experience, expertise, and skill.

To learn more about our bridge engineering and manufacturing, contact us for a quote or to answer any questions. Or start building your scope and bridge with our new interactive tool the Bridge Scope.

Pre-Engineered Building Solutions Set Construction Industry for Growth

With new bridges and infrastructure on the way, we expect 2020 to be a big year for the construction industry. In addition, laborers are working hard to improve projects by enhancing the design and building process. As of late, the pre-engineered building solution has had a great effect on the construction industry. For example, it is meeting the increasing demand for modern infrastructure. This involves innovative, cost-effective, and timely construction. Above all, it’s important for construction laborers to understand the difference between building solutions. This also includes planning, design, and, of course, construction. As a result, they can determine the best solution for their project.

Pre-Engineered Building

During the pre-engineered building process, construction materials and its components are manufactured at a factory, then assembled on site. Not only does this save time, but it also ensures a more successful project outcome. In addition, this type of building solution is progressively setting the construction industry for growth in 2020.

“The construction industry is projected to grow, as a result of increasing demand for pre-engineered building solutions that reduce construction time and cost.”

Andrew Heycott, CEO of Mabati Rolling Mills

Advantages

Different from conventional construction, pre-engineered building solutions still provide uniqueness and custom-built features. Often times, they are also less expensive. Significantly, there are numerous advantages that come with these building solutions.

  • Construction Time
  • Versatility
  • Design
  • Energy Efficiency

Construction Time

Every advantage of a pre-engineered building solution will involve saving time on construction. Similarly, the goal for most projects is to complete them on time or sooner. These types of buildings also include a wide range of structural and aesthetic equipment. This combined with the use of customized design software quickens the process of project completion. Furthermore, choosing the materials and design ahead of time allows the manufacturing and erection of a construction project to be done at a quicker pace.

Versatility

Notably, pre-engineered buildings are highly versatile. As mentioned above, the wide range of structural materials provides more options when it comes to design. In other words, pre-engineered buildings can cater specifically to customers or architects, allowing them to choose which option will fit their needs. This versatility allows for customization and increases functionality. Every construction project should involve a plan or guide to follow. So, the more options available, the more precise a structure can be. For example, project managers and laborers are able to choose the most suitable design option or size specification for materials.

Design

Before building and erection, workers must consider the design aspect of the structure. The design process involves many steps such as preliminary research, worksite analysis, concept design, etc. A complete vision for design leads to a smoother building process. Significantly, modern-day technology such as computer analysis and design programs help to facilitate the overall design process. Once laborers understand the design of a structure, they can proceed to gather materials and physically assemble the structure.

Energy Efficiency

Protecting the environment is important in the construction industry. In other words, how can we increase infrastructure while providing as little harm to the environment as possible. Significantly, pre-fabricated building solutions are also eco-friendly and energy-efficient. Necessary parts of a structure such as roofing, insulation, coatings, and panels can be built using energy-efficient materials such as:

  • Recycled steel
  • Plant-based polyurethane
  • Fiberglass
  • Insulating concrete

U.S. Bridge Bridges

The science behind why and how we build quality bridges goes beyond the bridge type. At U.S. Bridge, we use speed and quality to create great experiences and construction outcomes. We engineer and manufacture steel bridges locally and globally because we believe in connecting communities everywhere. Get a quote today to start on your next project.