Navya Rao

June 18, 2025

10 minutes

Bridge Preservation

Bridge Preservation: The What, the Why, and the How That Keeps Bridges Standing

Ever drive over a bridge without giving it a second thought?

You’re not alone. Bridges are so deeply woven into our daily routines that most of us never pause to think about how they’re holding up. Just like any structure that battles weather, traffic, and time, bridges require regular maintenance to stay safe and strong.

This article is your walkthrough of what bridge preservation means. No heavy jargon, no engineering degree required, just a clear look at the methods, science, and thinking that go into keeping our bridges standing tall.

What Is Bridge Preservation?

Bridge preservation is the ongoing process of keeping a bridge in good working condition, ideally before it starts to show major signs of wear and tear.

Think of it like taking your car in for regular oil changes, tire rotations, and inspections. You’re not waiting for the engine to fail; you're making sure it doesn’t. Bridge preservation works the same way. It focuses on keeping structures functional, safe, and efficient for as long as possible with the least amount of disruption and cost.

Now, it’s easy to confuse preservation with rehabilitation or replacement, but they’re not the same:

  • Preservation: Proactive maintenance to slow deterioration. Example: Sealing a crack before water gets in and exacerbates the issue.
  • Rehabilitation: Fixing something that’s already failing. Example: Replacing worn-out bearings or resurfacing a badly damaged deck.
  • Replacement: Demolition and reconstruction. Usually, the most expensive and disruptive option.

In a nutshell, preservation is about doing a little now to avoid doing a lot later. And it’s a strategy that saves money, reduces closures, and keeps people safe.

Why Preservation Is Critical

So, why not just wait until a bridge starts falling apart to fix it? Because by then, it’s often too late — or far too costly. Preservation is about staying ahead of the problem.

Here’s why it matters:

Bridges carry thousands of vehicles daily. Even small issues like rust, cracks, or water leaks can turn into serious hazards if ignored. Regular preservation keeps potential risks in check, long before they become emergencies.

Take the I-35W bridge collapse incident in Minneapolis in 2007, for example. The failure of a single gusset plate, combined with years of deferred maintenance, led to the tragic collapse that killed 13 people and injured over 100. That event was a wake-up call across the country and a stark reminder of what happens when preservation is neglected.

Cost Savings

Fixing a failing bridge costs significantly more than maintaining a healthy one. A dollar spent on early maintenance can save five to ten dollars on future repairs. It’s financial common sense with structural benefits.

Less Disruption

Full-scale repairs or replacements often mean road closures, detours, and frustrated commuters. Preservation tasks, on the other hand, are usually smaller, faster, and less intrusive.

In Portland, Oregon, early preservation work on the Fremont Bridge helped avoid major shutdowns. Instead of waiting for critical wear to escalate, the city performed targeted maintenance during off-peak hours,  keeping traffic flowing and sidestepping the massive delays that typically come with full-scale rehabilitation.

Environmental Impact

Preservation uses fewer materials, less machinery, and generates less waste than full-scale reconstruction. That’s a win for sustainability and resource conservation.

In short, bridge preservation isn’t just smart engineering, it’s smart planning.

The Technical Side – Explained Simply

Preserving a bridge might sound like a vague idea, but there’s a lot of technical work behind it, all broken into clear, methodical steps. Here’s how it works, minus the jargon.

This is the day-to-day care that prevents problems from ever starting. It's typically scheduled on a regular basis — monthly, quarterly, or annually — depending on the bridge’s location, materials, and exposure to elements.

  • Cleaning drains and joints helps prevent water from pooling, which can lead to rust or frozen damage. This is often done seasonally, especially before and after winter. Washing bridge surfaces like steel and concrete removes road salt, dirt, and grime. In colder regions where de-icing chemicals are used, this is typically done once or twice a year. Painting exposed steel parts protects them from corrosion. This is usually carried out every 5 to 10 years, depending on wear and environmental conditions.

Simple tasks, performed regularly, can dramatically extend a bridge’s life and postpone the need for major repairs.

Condition Assessments

Before any action is taken, inspectors need to understand the current state of the bridge.

  • Visual inspections: Trained eyes checking for cracks, rust, spalling (chipping concrete), and other signs of wear.
  • Hands-on checks: Sometimes it takes tapping, scraping, or probing to detect internal damage.
  • Tech-based methods:
    • Ultrasound to detect hidden flaws.
    • Ground-penetrating radar to check concrete depth or detect voids.
    • Drones and high-res cameras for hard-to-reach areas.
    • Sensors to monitor movement, stress, or vibrations over time.

This combination of people and technology helps identify issues early.

Preventive Measures

When inspectors spot risks, action is taken to stop damage before it spreads.

  • Sealing cracks in concrete to prevent water infiltration and freeze-thaw damage.
  • Installing expansion joint seals to handle bridge movement without letting in water or debris.
  • Deck waterproofing and overlays to protect the bridge’s surface from erosion and vehicle loads.
  • Improving drainage systems to steer rainwater away quickly and efficiently.

These are small investments that delay or even avoid major repairs.

Rehabilitation Efforts

When a part is already worn or damaged, rehabilitation steps in.

  • Deck overlays: Adding a protective layer to the road surface.
  • Beam strengthening: Using steel plates or carbon fiber wraps to restore or improve capacity.
  • Bearing replacements: Swapping out the parts that allow the bridge to flex with traffic and temperature changes.
  • Pier or abutment repairs: Fixing foundational damage caused by erosion or aging.

Still far less disruptive than a full replacement, these interventions keep bridges working safely.

Material Science at Work

Bridge preservation isn’t just about fixing old parts. It’s also about using smarter, more durable materials moving forward.

  • Corrosion-resistant materials like ASTM A1010 stainless steel and low-permeability concrete mixes (often using supplementary cementitious materials like fly ash or slag) offer longer service lives, especially in coastal or cold-weather climates. Fiber-reinforced polymers (FRPs) such as carbon fiber or glass fiber composites are used to strengthen beams and columns without adding much weight or bulk. Protective coatings and sealants — including epoxy overlays, silane sealers, and zinc-rich primers — form invisible barriers that repel water, salt, and chemicals.

These innovations don’t just protect what’s there — they also reduce the frequency and cost of future repairs.

Together, all these steps create a reliable cycle: inspect, maintain, monitor, and repeat. That’s how bridges stay safe without breaking budgets.

How Technology Supports Preservation

Bridge preservation has come a long way from paper checklists and clipboards. Today, technology plays a huge role in making preservation faster, smarter, and more accurate, helping inspectors, engineers, and agencies stay ahead of problems.

GIS-Based Tracking

Geographic Information Systems (GIS) help map every single bridge and track its condition over time. You can zoom into any bridge, see its inspection history, location-based risks (like flood zones or heavy truck routes), and plan maintenance with pinpoint accuracy.

Mobile Inspection Tools

Instead of lugging around manuals, cameras, and notebooks, inspectors now use tablets with specialized apps that:

  • Work offline in remote areas
  • Capture photos, sketches, and voice notes on the spot
  • Reference standards like the SNBI or AASHTO manuals
  • Automatically sync data to central systems

Tools like these save hours per inspection and reduce errors caused by manual entry.

Drones & Remote Sensing

Some parts of a bridge, think the undersides of rivers or tall piers, are tough (and risky) to access. Drones make it easier and safer to:

  • Capture high-resolution imagery
  • Detect surface cracks or corrosion
  • Build 3D models of structures for better analysis

Combined with infrared sensors and LiDAR, they can even detect internal issues hidden from view.

Sensors & Smart Monitoring

Smart bridges are no longer a sci-fi concept. Sensors can be embedded in key components to monitor:

  • Load stress
  • Temperature changes
  • Cracking or movement over time
  • Vibration patterns caused by traffic

This real-time data helps engineers make decisions before issues become emergencies, and it’s especially useful for high-traffic or high-risk bridges.

Data-Driven Decision Making

Modern bridge preservation relies heavily on data, and software platforms bring all that information together. From inspection reports and sensor readings to maintenance logs and GIS mapping, these tools give agencies a full picture of a bridge’s condition.

Platforms like AASHTOWare Bridge Management (BrM), inspectX™, and AgileAssets help transportation departments:

  • Prioritize which bridges need attention first, based on risk and deterioration
  • Forecast future needs, costs, and maintenance schedules
  • Demonstrate compliance with federal standards such as NBIS and SNBI
  • Prepare data-backed justifications for funding and planning

Challenges in Preservation

For all the progress in bridge preservation, it’s not always smooth sailing. Agencies, inspectors, and engineers often face some tough roadblocks.

Funding Gaps

Preservation doesn’t grab headlines like a brand-new bridge, so it often gets overlooked when budgets are tight. But deferring routine maintenance today can mean footing a much bigger bill later.

For example, routine preservation costs can range from $5,000 to $25,000 per bridge per year, depending on the structure and location. In contrast, replacing a typical bridge can cost anywhere from $2 million to over $10 million, not to mention years of planning, permitting, and disruption.

Please note: These figures are general estimates, intended to provide a ballpark comparison. Actual costs may vary significantly depending on project scope, location, and agency-specific factors.

The challenge lies in convincing decision-makers to fund work that prevents problems instead of reacting to them.

Competing Priorities

Departments of transportation juggle a lot — road repairs, traffic management, emergencies, and new construction. Bridge preservation must compete for time, money, and manpower, even though it often affects safety just as much as those other projects.

Aging Infrastructure

Many bridges in the U.S. were built in the 1950s and 60s. They weren’t designed to support today’s traffic volumes, heavier freight loads, or extended service life expectations.

According to the American Road & Transportation Builders Association (ARTBA), as of 2024, over 43,000 bridges in the U.S. are classified as structurally deficient, meaning they are in poor condition and require significant maintenance or repair. That’s about 7 percent of the nation's total bridge inventory.

Preservation becomes much harder and far more expensive when materials are already degraded or outdated.

Knowledge Gaps

Skilled inspectors and engineers are crucial to preservation, but many are nearing retirement, and there’s a growing gap in hands-on experience with complex structures. Plus, new preservation materials and techniques are evolving fast, requiring ongoing training.

Fragmented Tools & Systems

Sometimes agencies use  for scheduling, and another for GIS. That leads to silos, data loss, and inefficiency. Integrating everything into a single streamlined workflow is still a big challenge for many.

Looking ahead, more agencies are exploring integrated solutions that combine tools like BIM (Building Information Modeling) and GIS with bridge management systems, creating a more connected, efficient approach to preservation.

Preservation is clearly the smart move, but making it routine, well-funded, and widely adopted takes time, resources, and a shift in mindset.

Real-World Wins – When Preservation Works

Preservation isn’t just a theory or an ideal; it’s something that’s already working across the country. When done right, it can transform how bridges perform over decades. Here are a few examples that show what’s possible:

Case 1: Extending Bridge Life by Decades – Utah DOT

Utah’s Department of Transportation (UDOT) adopted a preservation-first strategy in the early 2000s. Instead of waiting for deterioration, they prioritized early action, like sealing decks, applying overlays, and replacing joints proactively.

The result?

Case 2: Fighting Corrosion – Florida’s Coastal Bridges

Saltwater and sea air are brutal on steel and concrete. Florida implemented protective coating systems and cathodic protection (a method that controls corrosion by using electrical currents) for its coastal bridges.

The result?

A significant drop in corrosion-related failures and millions saved in future repairs — all by planning ahead with preservation in mind.

Case 3: Smarter Budgeting – Indiana’s Preservation Plan

Indiana DOT shifted funding toward preservation and preventive maintenance and tracked performance metrics closely over time.

The result?

More bridges stayed in “good” condition longer, and fewer needed emergency fixes. They stretched every dollar farther by doing smaller repairs earlier.

Case 4: Embracing Technology – Smart Monitoring in California

California installed sensors and remote monitoring on key bridges in seismic zones. This lets engineers watch how structures respond to stress in real-time, especially after earthquakes.

The result?

Faster, more accurate post-event assessments — and the ability to act immediately when needed, rather than relying solely on manual inspections.

These examples prove that bridge preservation works. It’s cost-effective, safer, and smarter — and it's already shaping the future of infrastructure maintenance.

The Road Ahead: Making Preservation the New Normal

We’ve come a long way in recognizing the value of preserving our bridges — but there’s still more road to cover. For preservation to become the standard (not the exception), we need to rethink how we plan, fund, and talk about infrastructure.

Shift the Mindset: From Reactive to Proactive

The old habit was to wait until something broke. The smarter approach is to keep things from breaking in the first place. That means:

  • Treating preservation like essential health care for bridges — routine, consistent, and preventive.
  • Planning long-term instead of reacting to emergencies.
  • Valuing small fixes as much as big projects.

Make Data-Driven Decisions

Modern bridge preservation is powered by real-time data and predictive tools. We now have the ability to:

  • Forecast deterioration before it happens.
  • Prioritize bridges that need help the most.
  • Justify funding with clear performance metrics.

Agencies that lean into this shift are getting more value out of every dollar spent.

Encourage Collaboration

Preservation works best when everyone’s on the same page:

  • Engineers, inspectors, planners, and contractors must share information easily.
  • Federal, state, and local agencies need common goals and standards.
  • The public should understand why early maintenance matters (and why it saves money).

Stronger communication leads to better coordination and better bridges.

Invest in People and Tools

No preservation plan works without trained professionals and the right technology. The next generation of inspectors and an engineer's needs:

  • Ongoing training in both classic techniques and innovations.
  • Access to mobile tools, smart sensors, and integrated platforms.
  • Support to make informed, confident decisions in the field.

Final Thought: Preservation Is Progress

Preserving a bridge isn’t about clinging to the past; it’s about building a more resilient future. Every crack sealed, every joint replaced, every inspection recorded is an investment in safer roads, stronger communities, and smarter infrastructure management.

Preservation isn’t just good practice. It’s good sense.

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