In the first part of this series, we covered six ways that designers, scientists, and engineers have studied past bridge failures to figure out how to build better structures in the future. Here are six more.
1. Fireproofing bridges
At a time when more and more bridges are vulnerable to wildfires, terrorist threats, and destructive collisions by large boats and vehicles, modern fireproofing is becoming an integral part of many new and retrofitted bridges. Fire blankets are used to protect vulnerable areas, including gas lines and other utility infrastructure, from the most extreme types of heat and fire damage.
2. Seismic design and retrofit
Apart from wind damage, earthquakes have caused some of the most devastating damages to bridges — and complete failures — in history. That’s why scientists all over the globe have been developing systems for evaluating the potential risk of damage to bridges when they are impacted by seismic activity.
Historically, linear evaluations were the most common way to evaluate potential earthquake damage. Now, case studies are done using nonlinear analysis. This is valuable because bridges are subject to multidimensional behaviors when severe earthquakes happen. This includes twisting and bending. The resulting damage from these factors is costly, dangerous, and difficult to repair.
Engineers today use multidimensional analysis, supported through computer models, to develop new bridges and retrofit older ones.
3. Floating bridges
Do bridges actually have to rise above waterways? Of course not, and the state of Washington has proven it!
Several of the state’s waterways were impossible to cross with conventional structures. So, engineers found a way to build bridges on pontoons that float on the water instead. Watertight pontoons are connected together using steel cables that prevent sway. Next, a specialized type of concrete that’s able to withstand saltwater damage is applied to create the roadway. Pipelines are installed at the bottom of the pontoons to maintain a consistent temperature so the concrete on the roadway or walls doesn’t crack or separate while it’s being poured or drying.
4. Composite material bridge decks
Asphalt is a common bridge and road surface. It’s relatively inexpensive and easy to apply.
The issue: Asphalt doesn’t last long, especially when it’s used in areas where rain, snow, and other types of inclement weather impact it.
The solution: Bridge decks are now built using composite and recycled materials layered on top of each other. This increases the strength and durability of bridge surfaces. It also prevents cracking and helps remove water on road surfaces. It may cost a little more, but most bridge designers find it a worthwhile long-term investment.
5. Aesthetic bridge rails
Have you ever found yourself traveling across a bridge promising a beautiful view of a cityscape, waterfront, or valley only to have it blocked by a high, unattractive railing?
This was often the case along the Pacific coast in California. The state lead the way in developing aesthetically pleasing see-through railings that are as safe as old-school rails. They’re strong, even being made from lighter substances like aluminum and composite, recycled materials. The rails developed in California are used to preserve beautiful views across the United States.
6. New technology for inspecting submerged support structures
Conducting underwater bridge inspections is extremely dangerous. Highly experienced divers do visual inspections to figure out whether substructures are in good condition. They’re often hampered by murky water, strong currents, or floating hazards.
Robotic vehicles have replaced many human inspections, providing good visual information in a safer way. More recently, acoustic imaging has proven to be an even better alternative. It gives engineers the information needed to find structural issues that require a closer look. Only then do they send in divers for close-up, personal inspections.