In many infrastructure projects—especially in the field of noise protection—a recurring pattern can be observed: attempts to save money often lead to higher overall costs, lower acoustic performance, and significantly more technical effort. The paradox is this: the additional costs arise not because high-quality solutions are expensive, but because savings are made in the wrong places. Short-term savings repeatedly lead to long-term problems.
The Misleading Cost Advantage of Low-Quality Systems
The choice of wall type often determines whether a project can be executed economically. The noise barrier market offers a wide range of systems—many with decent insulation values. But truly high-performance absorption systems are rare.
Many supposedly inexpensive solutions advertise high absorption classes, appearing attractive at first glance. But this impression quickly evaporates: only open absorber systems can actually deliver what they promise in real conditions.
Closed systems—such as perforated metal cassettes or metal sandwich elements—may perform well in reverberation chamber tests, but behave very differently in practice. Their limited open area often leads to reflective behaviour under real operating conditions. A large portion of the sound energy is reflected back instead of being absorbed—something residents are all too familiar with.
The result: walls must be built higher or retrofitted later to achieve the originally intended effect. Thus, an apparently inexpensive solution quickly becomes a significantly more expensive structure.
Small Changes, Big Costs
How drastically technical compensations can impact a project budget becomes clear with the example of post spacing. In a recent project, the client—after awarding the contract to a cheaper supplier—had to reduce the post spacing from 4 m to 3 m for structural reasons.
This seemingly minor change results in:
- 25% more posts
- 25% more foundations
- 25% more earthworks, material, and installation
With post prices in the four-digit range per unit, this leads to a substantial cost explosion. Worse yet: the additional expense would have been avoidable if a system with sufficient performance had been selected from the outset. This is where the real cost structure of a project becomes visible—not in the product price, but in the downstream construction costs.
Quality-Oriented Planning Reduces Life-Cycle Costs
Quality in planning does not mean choosing the most expensive product, but the right one. Systems with high acoustic efficiency or the use of high-performance add-on elements—such as PIN—enable significantly lower wall heights. The better the effectiveness of the system, the less structural compensation is required—and the lower the actual total cost.
High-quality planning does not increase the budget; it prevents unnecessary expenses: reduced material use, less excavation, shallower foundations, lower loads, and overall reduced maintenance and life-cycle costs. Choosing quality is not a luxury—it is economically sound.
Add-On Elements: Effective—But Only When Designed Properly
As mentioned above, add-on elements are a powerful tool for improving the acoustic performance of a noise barrier without increasing its height. However, the differences in actual effectiveness are substantial.
Smooth, closed, or highly reflective surfaces (e.g., perforated sheet metal) can even degrade the shielding effect. A functional add-on system requires clearly defined geometry, effective edge guidance, and materials that do not contribute to reflection. Only systems whose performance has been verified through in-situ measurements according to EN 1793-5 and EN 1793-6 provide the acoustic benefit that matters economically. Anything else is a risk—to the project, the budget, and the final impact.
Conclusion: Quality Saves Money—Not the Other Way Around
Cheap systems almost always make projects more expensive in the end. The real costs arise from the structural measures required due to insufficient acoustic or structural performance. High-quality solutions, high-performance add-on elements, and professional planning prevent unnecessary post densification, oversized foundations, and expensive retrofits. Quality is not a cost driver—it is an economic tool and the basis for sustainable infrastructure projects.
Technical Background: Why Reverberation Chamber Tests Are Often Misleading
Many products are classified as “highly absorbent” based on laboratory values. This classification is derived from reverberation chamber tests (EN 1793-1), which measure how quickly sound decays in a room filled with noise barrier elements.
But real environments work very differently: along transport routes, sound typically hits the wall only once or twice before dispersing. This means that only truly high-performance, open systems achieve strong real-world effects.
In-situ measurements (EN 1793-5 and EN 1793-6) address this issue. They measure—on site and under real conditions—the actual absorption and shielding performance of a system. This standard is far more meaningful and will hopefully become the norm in the future.
Image: Reveberation Chamber TU Dresden; Foto: Henry Mühlpfordt – Eigenes Werk, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=9489088
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